THE GOLDEN NEMATODE HANDBOOK

Survey, Laboratory, Control,

and Quarantine Procedures

By

Joseph F. Spears, Assistant Director,

Plant Pest Control Division, Agricultural Research Service

066/ / / Mr Í I

S'f)

Agriculture Handbook No. 353

UNITED STATES DEPARTMENT OF AGRICULTURE

Agricultural Research Service

Washington, D.C. Issued September 1968

For sale by the Superintendent of Documents, U.S. Government Printing Office,

Washington, D.C. 20402—Price $1.25
FOREWORD

The history of nematology in the United States is characterized by its rapid

growth and by general recognition by growers, industry, and agricultural

workers of the importance of nematodes in limiting crop production.

The first regulatory activity against nematodes was in 1926 when the U.S.

Department of Agriculture's Bureau of Entomology and Plant Quarantine

imposed regulations against the bulb and stem nematode. Today, several hundred Federal and State people are engaged in regulatory nematology and are

spending about $4.5 million a year on surveys, enforcement of quarantine regulations, and the application of nematocides.

Before World War II, about 35 people were engaged in nematological research, and the annual appropriation was less than $150,000. Today, at least

175 persons are working full or part-time on nematological research, and the

annual expenditure is about $4 million.

The discovery of the nematocidal properties of dichloropropene-dichloropropane in 1943 marked the beginning of the present soil fumigation industry.

For the first time farmers and nurseryraen had a practical and economical

means of controlling nematodes. About the time of this discovery the golden

nematode was found on Long Island (1941). Although a handful of nematologists in the United States had been working on the nematode problem for a

number of years, the discovery of the golden nematode brought the problem

forcibly to public attention.

In 1953, nematologists discovered that the burrowing nematode, Radoyholus

similis, caused spreading decline of citrus, and in 1954, they discovered that

the soybean cyst nematode, Heterodera glycines, was causing economic losses

to soybeans.

After the discoveries in 1941, 1953, and 1954, survey, regulatory, and control programs were initiated and special methods were developed for' largescale control programs.

Regulatory measures and the laboratory and field techniques used to carry

out the program against the golden nematode are described in this handbook. Most of the methods are suitable for use on a large scale and are applicable to most other cyst nematodes. No other publication includes such a comprehensive treatment of a nematode control program. The information will

be valuable not only to those conducting regulatory and control programs involving the golden nematode, but also to agricultural administrators, plant

protection oflScials, and students in many other areas of agriculture.

Joseph F. Spears is well qualified to write this handbook. He was one of the

organizers of the program. He pioneered in the development of many of the

program operations and has been associated with the work in some capacity

for more than 20 years. He initiated the present chemical control program. In

addition, he has had broad experience with large-scale plant protection programs involving other nematodes and other organisms, such as insects and

fungi.

William F. Mai, Ph.D.

Professor

Department of Plant Pathology

Cornell University

Ithaca, New York

111
Trade names are used in this publication solely to provide specific information. Mention

of a trade name does not constitute a guarantee or warranty of the product by the U.S.

Department of Agriculture or an endorsement by the Department over other products not

mentioned.

IV
PREFACE

This handbook has been prepared to meet the needs of agricultural workers

interested in the protection of crops from nematode outbreaks. Most of the

procedures set forth in this handbook are the outgrowth of research conducted by the New York State College of Agriculture, Cornell University, and the

Agricultural Research Service (ARS) of the U.S. Department of Agriculture

(USDA). These methods and procedures have been successfully used for several years. Through the efforts of the scientists working on this problem these

methods are constantly being improved.

Many people have contributed in various ways to make this handbook possible. The author is sincerely grateful to all of them. Special acknowledgment

is made to personnel of the New York State Department of Agriculture and

Markets; the Department of Plant Pathology, Cornell University; the Nematology Section of the Crops Research Division and the Plant Pest Control Division, ARS, USDA ; and the Foreign Agricultural Service, USDA.
CONTENTS

Page Page

Introduction

History and origin of the golden

nematode

Origin

Discovery in the United States

The Genus Heterodera

Key to the mature cysts of the

more common species of

Heterodera

Type host plants

Biology

Life history __-:

Symptoms of infestation

Host plants

Rate of population increase

The potato and tomato industries -_-

The potato industry

The tomato industry

Control of the golden nematode in the

United States

Research and methods

Survey results

Survey procedures

Survey crew

Equipment

Field soil sampling

Plant-root examination

Labeling and recording

Sanitation

Laboratory procedures

Soil processing

Examination of soil samples

Checking specimens for viability

Regulatory

The golden nematode act

Quarantine

Approved regulatory treatments ^

Compensation

Chemical control

Chemicals to be used

Equipment needed

Calibration of fumigant metering systems

Field operations for shank injection equipment

Decontamination of equipment _

Precautions

Resistant potato varieties

The international problem of control _

2

2

3

4

4

7

8

8

10

10

11

12

14

14

14

15

15

19

19

19

19

21

21

22

24

25

26

26

30

32

32

34

35

36

37

37

40

42

48

43

45

49

World distribution of the golden

nematode

Algeria

Argentina

Austria

Belgium

Bolivia

Canada

Canary Islands

Chile

Czechoslovakia

Denmark

England and Wales

Faeroe Islands

Finland

France

Germany (East)

Germany (West)

Greece

Guernsey

Iceland

India

Ireland

Israel

Italy

Jersey

Luxembourg

Netherlands

Northern Ireland

Norway

Panama

Peru

Poland

Portugal

Saarland

Scotland

Spain

Sweden

Switzerland

Union of Soviet Socialist Republics

United States

Yugoslavia

Literature cited

Appendix I—World potato production

Appendix II—Intensity of infestation _

Appendix III—Soil sampling for

potato root eelworm

The United Kingdom method

The Dutch method

Comparison of the two methods

55

55

56

56

58

58

59

59

59

61

61

63

63

64

64

64

65

66

66

66

66

67

68

68

68

69

69

69

71

71

72

72

72

73

73

74

74

75

75

75

75

77

79

80

81

81

81

81

VI
THE GOLDEN NEMATODE HANDBOOK

Survey, Laboratory, Control,

and Quarantine Procedures

By

Joseph F. Spears, Assistant Director,

Plant Pest Control Division, Agricultural Research Service

INTRODUCTION

The golden nematode is undoubtedly the most

serious pest threatening the American potato

industry. It is recognized throughout the temperate regions of the world as one of the most

difficult of all crop pests to control. It also attacks tomatoes, but it is not a major threat to

this crop.

The golden nematode is the subject of stringent quarantine regulations in most countries

where it occurs. Countries not known to be infested have rigid regulations governing the importation of potatoes or other products that

might carry the pest. Agricultural officials in

countries where the nematode occurs agree that

potatoes cannot be grown economically on land

containing large numbers of the nematode.

Tuber yields of less than seed planted have been

reported from fields heavily infested.

The golden nematode poses many problems

in its control. It has a remarkable ability to survive under unfavorable conditions. It can remain dormant in the soil in the absence of host

plants for many years because the unhatched

nematode is protected by both the shell of the

eggs and the durable cyst wall, which acts as a

protection against adverse conditions. The lack

of any one aboveground symptom to betray its

presence is an aid to its survival. Thus, light or

scattered infestations of the nematode reproduce and increase in the soil undetected. During

this time of buildup, infestations may spread to

new fields, and because the populations are low

they will not be detected by the best survey

techniques. This type of spread and slow buildup of populations is undramatic, and low levels

of infestations are always one step ahead of

survey. Crop reduction as a result is negligible.

The buildup may require 5 to 7 years or more

after introduction of the pest into a field before

noticeable crop injury and reduction in yields

occur. However, buildup of nematode population increases like compound interest until the

crop is destroyed.

As the damage caused by plant nematodes is

becoming more widely recognized, general interest in the problem is increasing and a mounting volume of questions are being asked by

growers. Most countries now have nematologists devoting their efforts to problems caused

by plant nematodes. More and more surveys are

being undertaken in many countries to determine distribution and identification of plant

nematodes.

Control of the golden nematode in most areas

of the world still depends on crop rotation. However, scientists have been devoting more and

more attention to the development of resistant

varieties. Resistance-breaking biotypes of the

golden nematode have now been reported from

several countries, and investigators are devoting much attention to the influence this has on

the problem.

The use of nematocides to control the golden

nematode is also being investigated by workers

in several countries. Some European countries

are making limited use of these chemicals. However, the high cost of chemicals has been a factor in preventing large-scale use.

In the United States the use of nematocides

is increasing annually for nematode control on

many crops. Over 100 million pounds of nematocides are used annually in this country, principally on tobacco, pineapple, and vegetable

soils. Nematocides are applied to about 1 million
AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OP AGRICULTURE

acres. In the United States and Canada, the use

of nematoeides has been adopted on a large scale

in an effort to eliminate the golden nematode.

Continuing research will undoubtedly refine

present methods of control. Basic information

being gathered by nematologists will develop

more efficient control measures. Screening of

chemicals for control or eradication is being

stepped up. As more effective and less expensive

nematoeides are developed, together with more

efficient methods of applying them, the use of

chemicals for nematode control will undoubtedly

increase.

HISTORY AND ORIGIN OF THE GOLDEN NEMATODE

During Germany's campaign against sugarbeet nematodes in 1881, Julius Kuhn observed a

cyst-forming nematode attacking potatoes. He

recorded it as a curiosity—a possible subrace of

Heterodera schachtii U8).^

That the nematode was actually a serious

parasite of potatoes was not established, however, until 1913, when Massée (Scotland) and

Zimmerman (Germany, 1914) proved Kuhn's

*'oddity" to be the real cause of what was then

known as **soil sickness of potatoes" (P).

Within the following decade, the existence of

the pest was discovered in England (1917),

Sweden (1922), and Ireland (1922). Still

thought to be a new species of Heterodera

schachtii, the pest gained the common English

name of ''potato root eelworm" (4^8).

In 1923, however, Wollenweber observed that

"potato larvae are slightly shorter than those

of the sugarbeet nematode, and that their cysts

are pear-shaped rather than lemon-shaped." Declaring that this was an entirely different species from that attacking sugarbeets, he proposed

the name Heterodera rostochiensis since his

specimens came from Rostock, Germany (iS),

Despite Wollenweber's findings, scientific

journals of the day continued to refer to the

nematode as a race of the sugarbeet nematode (15). It was not until the excellent work

of Franklin, years later, that Heterodera rostochiensis was given general recognition as a

valid species.

The impact of the pest on the world's potato

industry 2 has been spectacular since infested

seed had been spread throughout much of the

world long before Heterodera rostochiensis was

named. Infestations have been discovered in

such widely separated nations as Peru (1952),

Iceland (1943), India (1961), and Panama

(1967).

^ Italic numbers in parentheses refer to Literature

Cited, p. 77.

^ For information on world potato production, see

Appendix I.

Origin

For many years it was thought that the

golden nematode originated in Europe. Some

workers suggested that the nematode's sudden appearance was by mutation from a

species of Heterodera, originally a parasite of

some European garden weeds or ornamentals.

Some advanced the theory that it was transported from an isolated area where the species

may have lived on a sporadically occurring

Solanacaea.

On April 3, 1951, a ship from Peru arrived

at the port of Seattle, Wash. Plant quarantine

inspectors of the USDA making routine inspection of the ship for plant pests collected

soil from potatoes in the ship's stores and

found the golden nematode. On September 25,

1951, a ship from Peru in the New York harbor was inspected and golden nematode cysts

were found in the ship's stores in two different

collections. These specimens were examined by

USDA nematologists and were confirmed as

being Heterodera rostochiensis. Since this pest

had not been previously reported in Peru, a

careful check was made of the ship's log to

determine if the ship had taken on stores in

other ports. All evidence pointed to the fact

that the contaminated potatoes had originated

in Peru.

A. L. Taylor of the Nematology Section,

Crops Research Division, ARS, wrote to

C. Bazan de Segura, Centro Nacional de

Investigación y Experimentación Agrícola de

la Molina, Peru, advising of the finding of the

golden nematode on ships from Peru and suggesting that a search be made in the country

for the presence of the pest. As a result of this

communication the nematode was found in

February 1952 on potatoes from Tarma. A

scientist from ARS, who was in Peru at the

time the discovery was made, brought specimens back to Mr, Taylor in May 1952. Mr.

Taylor confirmed identification as Heterodera

rostochiensis.

The first account of this discovery was published in 1952 (36), The author, C. Bazan de

Segura, stated that it was her opinion the

Heterodera rostochiensis is indigenous to the
THE GOLDEN NEMATODE HANDBOOK

Andes. Later investigations conducted by

Peruvian scientists determined that the nematode was widely distributed and was of an

ancient origin.

Later, the nematode was discovered in the

highlands of Bolivia and Argentina, where it

is believed to be indigenous also.

The theory basing Heterodera rostochiensis

origin in Peru is accepted by most nematologists today. Also, most botanists agree that

the potato originated in Peru. Thus, one might

logically ask why the golden nematode did not

become a problem to European potato growers much earlier.

Potato tubers from South America had been

well-distributed in Europe by early 1600. No

doubt cysts of Heterodera rostochiensis were

also distributed with these tubers, but under

primitive cultural methods buildup was slow.

By 1700 the potato had become a vital part of

the basic food supply in Ireland, Scotland,

Germany, and other western European countries.

However, little was done by agricultural

scientists to improve the potato. Their interest

was generally for its botanical characteristics.

These earlier horticulturists did not seriously

influence potato production or improvement

of the few varieties that existed during this

period. There was no serious attempt to develop new potato varieties until after the crisis

in Ireland caused by late blight (1845). The

potato famine that resulted gave the necessary

stimulus to a new era of potato breeding,

which led to commercial potato production.

From the mid-1800's to the end of that century there were revolutionary changes in potato growing. Plant breeders for the first time

were guided by scientific principles of heredity and immunity in crop improvement.

Between 1856 and 1876, large numbers of distinct varieties were produced and consumption

of the potato in the people's everyday diet

increased. It was probably during this period

of intensified growing of potatoes and the distribution of seed for the establishment of

commercial potato production that Heterodera

rostochiensis was able to gain a foothold in

Europe's potato fields.

Discovery in the United States

A farmer near Hicksville, Long Island, N.Y.,

was little concerned in 1934 when he noticed a

few isolated spots in his potato field where

vines were stunted and off color. Within 4

years, however, the spots had multiplied and

commercial losses to his potato crop were being sustained. The farmer made repeated requests to his county farm bureau agent for

FIGURE 1.—Mature females attached to the roots become golden in color, hence the popular name

"golden nematode" in the United States.
AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

soil analysis or other explanation of his crop

injury (5).

In July of 1941, Orson S. Cannon, a graduate student of the Department of Plant

Pathology, Cornell University, attached to the

Nassau County Farm Bureau, Long Island,

visited the potato field and observed that the

stunted and off-color appearance of the potatoes v^as similar to spots in sugarbeet fields

infested with Heterodera schachtii, with

which he was familiar (^). Cannon examined

potato roots from the field and found numerous swollen female nematodes on the roots.

Suspecting that this was the causative organism, he took specimens to the USDA Bulb

Laboratory in Babylon, Long Island, where

B. G. Chitwood, USDA nematologist, identified the specimens as Heterodera rostochiensis

{28). Subsequent examination of the property

showed that the entire field was infested and

crop losses were as high as 70 percent; in an

adjoining field, marked injury was apparent

{11)^

Available information on the distribution of

the pest indicates that all Long Island infestations may have originated from this 40-acre

field. The reuse of burlap bags for picking

potatoes and the movement of farm machinery

Iby renters were major factors in the local

spread of the disease. More than 30 additional

fields farmed by the operator of the original

infested field have since been found infested.

How and when the nematode gained entrance

into the United States is not known. However,

it could have been brought on military equipment being returned to Long Island military

camps after World War I. From the extent of

the infestation In 1941 and the history of the

field, the nematode had probably been present

for 20 years before it was identified {IS).

H. rostochiensis is usually called the potato

root eelworm in most European countries.

However, to avoid confusion with other potato

nematodes in the United States, Chitwood

gave the pest its popular name of "golden

nematode'' (7) because the flask-shaped immature females attached to the roots become

golden in color about the time the plants begin

to bloom (fig. 1).

THE GENUS HETERODERA'

The golden nematode {Heterodera rostochiensis Wollenweber, 1923) {51) belongs in the

"rostochiensis group" of the genus Heterodera

Schmidt, 1871 {35). This group is typified particularly by the globular to ovate shape of the

white females and cysts, and the character of

the cyst wall pattern (fig. 2). Specific identification is based primarily on vulva-anal size

and relationship, and to some extent, on

morphological characters of the females and

males, if these are available (fig. 3).

When H. rostochiensis nematode was first

discovered in this country about 25 years ago,

there was in the group only one other known

and described species, H. punctata Thorne,

1928 {46). Since then several very closely related species have been found, and their accurate identification requires the efforts of

someone thoroughly familiar with all the

species.

In 1953, Cobb and Taylor {16) described

H. leptonepia found in potatoes obtained from

a ship's stores at Callao, Peru. This form is

distinctive especially because of the strikingly

slender larvae. Shortly after that, another

species, H. tahacum Lownsbery and Lownsbery, 1954 {25), from tobacco in Connecticut

was described. In 1959, a Heterodera, still undescribed and intermediate between H. rostochiensis and H. tahacum was found on horsenettle, Solanum carolinense, in Virginia; it is

known to occur in other areas also. In 1961,

another Heterodera in the rostochiensis group

was found on tobacco in Virginia. These forms

have been referred to, respectively, as the

"horsenettle-cyst nematode" and the "Osborne

cyst nematode" {29). The latter is closely related, and possibly identical, to H. tahacum.

Knowing of the above closely related nematodes and keeping in mind the very probable

existence of still undiscovered new species in

the "rostochiensis group," one should be very

cautious and thorough before concluding that

any globular cysts that might be associated

with potatoes are actually the golden nematode.

Key to the Mature Cysts of the More

Common Species of Heterodera ^

This key is designed to facilitate identification of the more common species of Heterodera

that might be encountered in soil samples collected during a survey. Only characters of the

mature cysts and their contents—that is, eggs

with second stage larvae—are used. Certain

characters used in the key may not be visible

on other than fully mature cysts.

^ Prepared by M. Golden, nematologist, Crops Research Division, ARS.

* Prepared by A. L. Taylor, nematologist. Crops Research Division, ARS. (Retired in 1967.)
THE GOLDEN NEMATODE HANDBOOK

BN 271

FIGURE 2.^—Numerous immature swollen females on the roots of a potato plant.
AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

FIGURE 3.—The golden nematode of potatoes, Heterodera rostochiensis Wollenweber, 1923: (A) Infective larva,

hatched from egg; (B) head of infective larva: (C) adult male; (D) head of adult male; (E) young adult

female; (F) section of cyst wall (7).
THE GOLDEN NEMATODE HANDBOOK

Measurements of larvae are from Fenwick

and Franklin (18) for most species, from Jones

(22) for H, carotae, from Ichinohe (21)

for H. glycines, and from Kirjanova (23) for

H. fici.

1. Body of cyst, ovoid to globular, that is,

with posterior portion rounded and

vulva not located on a distinct protuberance

Heterodera rostochiensis group 4

Body of cyst, lemon-shaped, that is, v^ith

vulva located on a distinct protuberance 2

2. Basic element of pattern of outer layer of

cyst wall at middle portion of cyst,

short zigzag lines with little or no trace

of regular transverse arrangement;

sometimes modified to appear as network 3

Basic element of pattern at outer layer of

cyst wall at middle portion of cyst,

straight or wavy lines at right angles

to axis of cyst; sometimes broken by

short oblique or vertical lines; outer

layer of cyst may have grainy appearance Heterodera cacti group 7

3. Mature cysts with dark bodies (brown

knobs) and often sheaf-shaped object

(lining of vagina) at posterior end. On

immature cysts, these are seldom visible, and then do not appear dark

Heterodera sckachtii group 8

Mature cysts without brown knobs or

sheaf-shaped object at posterior end

Heterodera gottingiana group 11

4. H, rostochiensis group. Cyst often ovoid,

anus located at a transparent spot on

cyst so that anal and vulvar openings

appear to be about the same size when

seen by transmitted light. Hyaline portion of larval tail much longer than

stylet Heterodera punctata

Cyst ovoid to globular; anal opening appears much smaller than vulva opening.

Hyaline portion of larval tail about the

same length as stylet 5

5. Larvae very slender; length about 39

times greatest width; orifice of dorsal

oesophageal gland about two-thirds

stylet length posterior to stylet knobs^ _

Heterodera leptonepia.

Length of larvae about 22 times greatest

width; orifice of dorsal oesophageal

gland about one-fourth stylet length

posterior to stylet 6

6. Distance between vulva and anus about

two and one-half times diameter of

vulva Heterodera rostochiensis

Distance between anus and vulva about

one and one-half times diameter of

vulva Heterodera tabacum

7. H. cacti group. Hyaline portion of larval

tail about as long as stylet ; stylet knobs

concave anteriorly ._ Heterodera weissi

Hyaline portion of larval tail usually

shorter than stylet ; stylet knobs convex

anteriorly Heterodera cacti

8. H, schachtii group. Cysts always with distinct, coarse punctation consisting of

dots of uniform size but not in rows;

brown knobs closely clustered around

vulva. Hyaline portion of larval tail at

least one and one half times longer than

stylet Heterodera avenae

Cyst with or without punctation, fine and

mostly in rows ; brown knobs not closely

clustered around vulva. Hyaline portion

of larval tail about as long as stylet 9

9. Average length of larvae:

480 microns 10

about 460 microns Heterodera schachtii

10. Avëfage length of larvae:

484 microns Heterodera glycines

502 microns Heterodera trifolii

518 microns

Heterodera schachtii galeopsidis,

11. if. gottingiana group.

Average length of larvae:

414 microns Heterodera cruciferae

454 microns Heterodera carotae

474 microns ^Heterodera gottingiana

405 microns Heterodera humuli

406 microns Heterodera fici

Type Host Plants '

Many lists of host plants of Heterodera

species have been published, but it seems probable that many of these are inaccurate in that

they include plants that are not hosts of the

species discussed. This is true especially of the

older lists and of those based on information

compiled from the literature rather than from

host tests. To avoid this particular error, the

following list of host plants includes only the

type host of each species and an indication of

the other plants that it attacks, so far as

there is general agreement or information on

host tests available. That is, the list is not intended to be complete, but I believe it is accurate so far as what is included is concerned.

^ Prepared by A. L. Taylor, nematologist, Crops Research Division, ARS. (Retired in 1967).
8 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

The species of Heterodera and their principal hosts are as follows:

H. schachtii. Type host, sugarbeet (Beta

vulgaris L). Also other Chenopodiaceae, many

species of Cruciferae and various species of

other plant families {U7). It seems possible

that H. schachtii attacks a wider variety of

plants than any other known species of Heterodera.

H. gottingiana. Type host, garden peas

(Pisum sativum L.) and other Leguminosae.

But according to Oostenbrink {31), this species

does not attack beans (Phaseolus vulgaris L.),

clover (Trifolium spp.), alfalfa {Medicago

sativa L.), or soybeans (Soya max Piper).

H. trifollii. Type host, red clover {Trifolium

-pratense L.) and other Leguminosae, including beans {Phaseolus vulgaris L.) but not peas

{Pisum sativum L.) alfalfa, or soybeans.

H. glycines. Type host, soybean {Glycine

max L.) and snap bean {Phaseolus vulgaris

L.), Adzuki bean (P. angularis), vetch {Vicia

sp.), annual lespedeza {Lespedeza stipulacea

Maxim.), henbit {Lamium sp.).

H. major. Type host, oats {Avena sativa

L.) and other Gramineae.

H. cruciferae. Type host, cabbage {Brassica olerácea L.) and other Cruciferae.

H. carotae. Type host, carrot {Daucus carotae L.). Wild carrot {Daucus carotae) is the

only other known host {22).

H. humuli. Type host, hops {Humulus lupulus L.) and other Urticaceae.

H. galeopsidis. Type host, hemp nettle

{Galeopsis tetrahit L.). Also other Labiatae

and some species of Chenopodiaceae and Carophyllaceae {22).

H. fici. Type host, rubber plant {Ficus sp.).

H. weissi. Type host, knotweed {Polygonum

pensylvanicum L.). No other hosts known.

H. cacti. Type host, Phyllocactus {Epiphyllum ackermanni) and other Cactaceae.

H. rostochiensis. Type host, potato {Solanum

tuberosum L.). Also tomato {Lycopersicon

esculentum Mill.) and a few other species of

Solanaceae {30) but not tobacco {Nicotiana

tabacum L.) (^5).

H. tabacum. Type host, tobacco {Nicotiana

tabacum L.) and tomato.

H. punctata. Type host, wheat {Triticum

vulgäre Vill.) and other Gramineae.

BIOLOGY

Life History

The golden nematode passes through the egg,

larval, and adult stages in its development.

From 38 to 48 days are required for the eggto-adult cycle {9).

The eggs hatch within the dead, swollen

bodies of fertilized females, which are called

cysts. Cysts are flask shaped and are much

smaller than a pinhead. Each cyst may contain up to 500 eggs. The cyst is a protective

covering for the eggs and is resistant to chemicals, to drying, and to some soil organisms

(fig. 4).

In the spring when the soil temperature is

around 60° F. a chemical given off by potato

or tomato roots stimulates larvae to hatch from

the eggs, leave the cyst through an opening in

the wall, and migrate to host plants. Larvae

enter the roots where they feed. At temperatures below 55° F. there is little activity of the

larvae {10).

In the roots, golden nematodes take up a

position near the plant's vascular system and

then undergo a series of changes. The females

become stationary; they swell and break

through the roots, to which they remain attached by a thin neck. The males retain their

slender eellike form and mate with the females.

After fertilization, several hundred eggs develop within the female whereupon the female

dies.

The golden nematode cyst is visible to the

unaided eye. At first, it is pearly white. Later,

it turns golden, orange, and finally brown.

Cysts become detached from the roots and remain in the soil after the crops have been

harvested {-iO) (fig. 5).

BN 30081

FIGURE 4.—Golden nematode females washed from

potato soil. Each cyst may contain up to 500 eggs.
9

•^Úffi 'Sfe^

THE GOLDEN NEMATODE

Background shows normal potato plant

(left) and one exposed to heavy neraatode

attacks.

Greatly magnified portion of infested root:

A, Females just breaking through root

surface.

B, partly developed cyst.

C, 0, and E, progressive color changes of

cysts.

F, cyst in the soil.

G, cross section of cyst showing eggs and

hatching larvae leaving cyst to enter roots.

FIGURE 5
10 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

BN 30006

FIGURE 6.—Aboveground symptoms of golden nematode damage.

Symptoms of Infestation

Soil populations of the golden nematode sufficiently high to cause plant damage are produced only after buildup on several potato

crops. At first there is no aboveground evidence of plant damage. This lack of distinguishable symptom of the early stages is an aid to

the organism. After host crops have been repeatedly grown on infested land, then distinct

aboveground signs of damage begin to appear

UO) (fig. 6).

The first sign is poor grovi'th of plants in

small spots in the field. These spots are similar

to that of plants in lovi? spots in wet years and

high spots during dry years. No one plant

symptom alone can be relied upon as evidence

of the disease. If the infestation grows, the

spots become larger and additional spots appear (27).

Aboveground symptoms anpear only in the

presence of large numbers of nematodes in the

soil. Heavy infestations cause considerable

wilting of plants, especially during midday,

stunting of growth, poor root development, and

poor plant growth. Before enough nematodes

develop in the soil to cause aboveground symptoms, immature females may be seen on the

roots. By carefully removing the plants and

roots at blossom time, the white, yellow, or

golden flask-shaped females attached to the

root may be seen with the unaided eye (4-0).

Populations of the golden nematode on Long

Island are so low that aboveground symptoms

seldom occur except in the experimental area

of the golden nematode laboratory. In this area

symptoms of heavily infested plants are generally evident the latter part of May and early

June. Extensive soil surveys detect infestations

as soon as they reach the discovery level.

The effect of the golden nematode on tomatoes is similar to that on potatoes. Growth of

plants is retarded and wilting is particularly

noticeable (fig. 7). Leaves of heavily infested

plants are purplish, instead of yellowing as in

potatoes, and the lower leaves may die {38,

p. 178).

The nematode in the early stages of the attack on tomatoes causes slight swelling of the

roots, which may be confused with galling

caused by the root-knot nematode {38, p 178).

Host Plants

The only commercial crops known to be attacked by the golden nematode are Solanum

tuberosum (potatoes), Lycopersicon esculentuw.

(tomatoes), and S. melongena (eggplant)

{27).
THE GOLDEN NEMATODE HANDBOOK 11

BN 29988

FIGURE 7.—(Left) Healthy tomato plants. (Right) Tomato plants stunted by the golden nematode.

Among other plants that may also become

infected, thereby helping to propagate this pest,

are Solanum dulcamara (bitter nightshade),

S. rostratum (buffalo bur), S. triflorum (cutleaf nightshade), S. elaeagnifoliuw. (silverleaf

nightshade), S. blodgettii, S. xanti (purple

nightshade), and S. integrifolium (tomato

eggplant) {15).

Plant breeders have found about 90 species

of the Solanum to be host of the golden nematode. Although most of these plants are wild

species not occurring in the United States,

most do occur in South America {38 p. 176).

Rate of Population Increase

Damage by the golden nematode to host

crops is caused by mass invasion on the roots

by nematodes that kill or damage the root system, depriving the plant of the necessary food.

The relative increase in the number of nematodes in the soil from the growing of a potato

crop is greatest when the number of nematodes

is low {27). This is because the plant is able

to produce a vigorous root system, and the

nematodes have an abundant root system on

which to feed. The nematodes attacking the

root are less concentrated, and thus few roots

are killed. However, as the number of nematodes increases in the soil, the annual increase

of nematodes from the continual growing of

potatoes is less because more roots are killed

and both the plant and the nematodes are deprived of an adequate food supply.

When the concentration of nematodes

reaches a level to cause total failure of the

potato crop, the number of living nematodes

in the soil drops substantially {27). This, of

course, is due chiefly to the lack of food to

sustain the population. The following year it

may be possible to grow a fair potato crop

because enough nematodes have died so the

plant can produce a root system to sustain itself. At these high degrees of infestation, the

crop will always be irregular and always be

poor.

In the absence of host crops, the rate of decrease in viable cysts may be as much as 50

to 80 percent the first year; however, the rate

of decrease continues at a smaller rate with

some viable cysts remaining for many years.

Grainger {19) of the West Scotland Agricultural College reported that the golden nematode wastes away at a fairly standard percent

annually in the absence of host plants, because

of normal aging and ultimate death of the

nematode and attack by other organisms.

Normal aging appears to be logarithmically

dependent on temperature, being greater in

warm climates than in cooler climates. Infestations of the golden nematode never assume

very serious proportions in warm countries,

where natural wastage is so high that even relatively short crop rotations would reduce populations to very low levels and longer rotations

would eliminate them entirely. In cool areas,

like Scotland, however, the annual wastage

could be as low as 18 percent. Grainger also

says that a moderate infestation of nematodes,

still in a viable state, could be expected to

cause serious disease "up to 30 years after

the last potato crop." This expectation, according to Grainger, has been confirmed by careful checking of actual instances, which involved persistence of 27 to 28 years {19).

United States Department of Agriculture research workers Chitwood and Feldmesser {l-k-)

found the increase on one potato crop on Long

Island to be about tenfold to twentyfold until

approximately 50,000 cysts per plant were
12 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

VIABLE CYSTS PER ACRE

10,000,000,000

1,000,000,000 -

100,000,000

10,000,000

1,000,000

100,000

10,000

1,000

100

10

1

CONTINUAL CROP FAILURESj

CROP SEVERELY DAMAGED

DAMAGE APPEARING IN SPOTS

*

DETECTABLE LEVEL BY

SOIL SAMPLING V!

VIRTUALLY

INDETECTABLE:v

NO PLANT SYMPTOMS

CROP

DAMAGE

I

1

0 1 2 3 4 5 6 7 8 10

YEAR

FIGURE 8.—Increase in golden nematode populations in a continuous potato culture, assuming a tenfold increase.

formed. Research workers in the Netherlands

have, in general, agreed with USDA findings.

In the Government-enforced rotation program,

the Netherlands has assumed, for practical purposes, a tenfold increase of the nematode on a

crop of potatoes and a decrease of 50 percent

in the absence of a potato crop.

Figure 8 shows graphically an increase of

golden nematode infestation in a continuous

potato culture assuming a tenfold increase (4-4).

THE POTATO AND TOMATO INDUSTRIES

The economic potential of the golden nematode, if left uncontrolled, can have serious effects on the potato industry. Potatoes are a

major food crop in many countries.

Potato production in 1966 in the principal

producing countries, estimated at 5,100 million

hundredweight (100 lb.), was 1 percent above

the 1965 crop but 2 percent below the 1960-64

average. Total acreage, estimated at 44 million

acres, continued its gradual downward trend,

whereas yields in general increased. Higher

yields more than offset the effect of decreased

acreage.

Tomatoes are not as widely grown as potatoes ; however, they are an important crop for

both the fresh market and for processing.

Tomato production in 1965 in the principal

producing countries of the world is estimated

at 420 million hundredweight produced on

about 2.5 million acres.

Europe leads the world in tomato production, followed by North America, the Near

East, Latin America, the Far East, Africa,

and Oceania. The 10 leading tomato-producing

countries are United States, Italy, Spain,
PRODUCTION PERCENT OF

SEASON 1.000 CWTS. U. S. CROP

WINTER 4,300 1.6

EARLY SPRING 3,900 1.5

LATE SPRINGn 24,400 9.2

EARLY SUMMERS 14,000 5.3

LATE SUMMER 34,900 13.1

FALL 184,500 693

TOTAL 266,000

Figures under state nemes indícete the production

of Ihet stete in thousand hundredweights and the

percentege of the U. S. crop (1958-62 averaged

FIGURE9

M
14 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

Bulgaria, Brazil, Japan, Greece, Rumania,

Mexico, and Argentina.

The Potato Industry

Potatoes are grown commercially in every

State (fig. 9), and there is not a single month

in the year when potatoes are not being

planted or harvested somewhere in the country

(^9). Potato yields per acre have risen from

a national average of 80 hundredweight per

acre in 1940 to 210 cwt. in 1966. It has been

predicted that the national average per-acre

yield may rise to as much as 250 cwt. by 1975.

The total acreage decreased from 2.8 million

in 1940 to about 1.5 million in 1966.

Potatoes have a market value of about $600

to $800 million. When transportation, packaging, and marketing facilities are included,

potatoes are a $3 billion industry. The 10

leading potato-producing States are Idaho,

Maine, California, New York, Washington,

North Dakota, Minnesota, Wisconsin, Colorado,

and Oregon.

As a potato-producing area, Sufifolk County,

Long Island, is outranked in the United States

only by Aroostook County, Maine, and Bingham County, Idaho. The potato acreage on the

Island was rapidly expanded during World

War II. It may have been during this expansion that the golden nematode spread from the

original field in Nassau County to eastern

Suffolk County—a distance of over 100 miles.

Potato production on Long Island reached its

peak in 1946, when well over 62,000 acres were

produced. It decreased to about 40,000 acres in

the midsixties.

The yield per acre, which rose rapidly during and following World War II, continues to

increase but at a slower rate. In recent years,

yields have averaged 250 to 260 cwt. per acre.

Of this yield, about 235 to 240 cwt. may be

sold ; the rest is offgrade or used for home consumption.

Hicksville—once the center of potato production in Nassau County—is now the center

of a large suburban area of New York City.

The population of Nassau County has grown

from about 400,000 in 1941 to more than

1,400,000 in 1967. Almost all of the infested

potato fields in Nassau County have become

house lots or industrial sites. The golden nematode, however, continues to threaten the potato industry in Suffolk County.

The Tomato Industry

Tomatoes are widely grown in the United

States for both processing and fresh market.

Most of the tomato crop is field grovra. About

275,000 acres of tomatoes are grown for processing; the crop value is about $160 million.

Tomatoes for the fresh market are grown on

170,000 acres; the annual value is about $190

million.

The 10 leading tomato-producing States are

California, Ohio, Florida, New Jersey, Indiana, Illinois, Pennsylvania, Maryland, Michigan, and New York.

CONTROL OF THE GOLDEN NEMATODE IN THE UNITED STATES

When the golden nematode was discovered

on Long Island in 1941, Cornell University

and the U.S. Department of Agriculture undertook a cooperative research program, and

the New York State Department of Agriculture and Markets and the USDA conducted

surveys. With the involvement of the United

States in World War II, however, the amount

of attention that could be devoted to the problem was limited.

By 1944, it had become obvious that the

nematode was much more widespread on Long

Island than it had been thought at first. In that

year, the State invoked a quarantine (33)^ and

the Bureau of Entomology and Plant Quarantine, USDA, began a survey in 19 potato-producing States east of the Mississippi River to

see if the nematode had spread outside Long

Island (10).

Following World War II, a cooperative Federal-State Golden Nematode Control Project

was established. Research facilities were greatly expanded, and the staff to operate the program was also expanded. The program was

divided into four main branches: Survey, laboratory processing of samples, quarantine enforcement, and research. Systematic soil surveys were begun of all fields on Long Island,

and surveys were expanded to include all potato-producing areas of the United States (fig.

9). Quarantine regulations were strengthened.

The following offices and laboratories have

been set up for the golden nematode program

on Long Island:

(1) A headquarters building at Hicksville

houses the program offices of both the USDA's

Plant Pest Control Division and the New York

State Department of Agriculture and Markets,

a laboratory, and a storage garage.

(2) A work unit office is maintained at

Riverhead, Long Island.

(3) New York State College of Agricul-
THE GOLDEN NEMATODE HANDBOOK 15

FiGURR 10.—Yields of Green Mountain potatoes per acre, based on a 5-year average.

ture, Cornell University, Department of Plant

Pathology, maintains a laboratory and greenhouse facilities at Farmingdale. Approximately 8 acres of land is available here for field

tests (ñg. 10).

Research and Methods

The laboratory at Farmingdale investigates

many phases of the golden nematode problem.

But its primary concern involves (1) investigations into rotation and resistance, biotype

buildup, race determination, and breeding of

potato varieties resistant to the golden nematode, and (2) investigations into chemical

control, which include screening of nematocides, evaluation of promising new nematocides, and determination of techniques and

conditions for optimum nematocide effectiveness.

The Plant Pest Control Division's Methods

Improvement Operations works closely with

Cornell scientists in their research program.

The Methods Improvement personnel develop

and improve machinery for applying nematocides to the soil, ways of field-scale testing of

candidate nematocides that show promise for

use in a control program, and ways of fieldscale testing of fumigants under tarpaulin

seal; they also develop regulatory treatments

to free of infestation nursery stock, farm machinery, burlap bags, and other commodities

so that they may be safely moved.

Research has gone forward with very significant progress in various fields. A chemical

treatment program and commercially acceptable varieties of potatoes resistant to the golden

nematode have been the two most valuable

findings in making a breakthrough in solving

this pest problem.

Survey Results

During the first 10 years of the program

the golden nematode seemed to be confined to

western Long Island, mainly Nassau and western Sufi'olk Counties. The vast potato acreage

of eastern Long Island remained free of the

nematode until 1950, when several infested

properties in Bridgehampton were found (fig.

11).

With establishment of systematic surveys

in 1946, the number of properties known to

be infested rose sharply. During the period

1946-52, the number of properties found infested averaged 34 annually, comprising 1,362

acres. Beginning in 1947 real estate interests

bought up much of Nassau County's agricultural land for houses and by 1956 few potato

fields remained. As farmland became scarce in

Nassau County, builders began to purchase

potato fields in western Sufi'olk County. During the period 1954-67, the average number of

properties found infested each year dropped

to 7, and the average acreage dropped to about

361 (fig. 12).

Since the golden nematode program began,

387 properties consisting of 17,151 acres, have

been found infested (table 1 and fig. 12). Of

this total about 11,413 acres of infested agricultural land have been permanently removed

from agriculture for real estate development

(table 2). Of the remaining infested acres,

4,389 have received soil treatment and have
Oï

pCv^

nINFESTED AREA

QUARANTINED AREA

>

o

O

t-"

1^c!

fö

a

>

o

a

o

o

Cl

M

ö

H

>

M

1^

o

so

c¡

C

w

H

FIGURE 11
THE GOLDEN NEMATODE HANDBOOK 17

been released for agricultural use, thus leaving 1,350 acres of agricultural land to be

treated.

The following tabulation shows the status

on January 1, 1968, of the infested land remaining to be treated:

Land use Acres

Vegetable crops 577,74

Potato land (Steuben County) 55.00

Cultivated sod 281.74

Pasture 108.87

Pending development (for real estate

purposes) 326.67

Total 1,350.02

Early regulatory action and the strict enforcement of the State quarantine has played

a large part in restraining the spread of the

golden nematode. The withholding of potatoes

and tomatoes from infested land has been the

most important single thing done to control

the spread. Fortunately, the infested fields

had low nematode populations, and the fields

were on an island.

However, administrators of the quarantine

had recognized, before discovery of the golden

nematode on Long Island or the enactment of

strict quarantine regulations, that the pest

could be transported to other potato-growing

areas.

During the early 1940's a few Long Island

farmers either moved to western New York or

operated farms both in western New York and

on Long Island. Because of the operational exposure of these farms, surveys are made annually in western New York.

On December 2, 1967, the golden nematode

was found on a 55-acre field in Steuben County,

N.Y., near the town of Prattsburg. The inACRES INFESTED

3,000

PROPERTIES

60

Nassau County

Acres

Properties

à.1^ ^4^ i

40

1,000

Suffolk County

lililí.

20

0

40

20

1940 1950 1960 1970

FIGURE 12.—Results of Long Island nematode survey. Number of properties and gross acreage infested, Nassau

and Suffolk Counties, 1941-66.
18 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

TABLE 1.—New infestation of golden nematode in Nassau, Suffolk, and Steuben Counties, by

years, 19Jfl-67

Nassau County Suffolk County Steuben County

Year Prop- Acreage Prop- Acreage Prop- Acreage Total Gross Remarks

erties infested erties infested erties infested properties acres^

1941.__- 2 115.66 0 0 0 0 2 116 First discovered in U.S.

1942 --- 9 541.86 0 0 0 0 9 542 Plant pulling or irregular pat1943 __ 8 437.36 0 0 0 0 8 437 tern of soil sampling, 1941-45.

1944 _-- 5 142.98 0 0 0 0 5 143

1945--^_ 5 165.88 0 0 0 0 5 166

1946-___ 41 1,656.50 0 0 0 0 41 1,656 Golden nematode project established—systematic soil sampling began.

1947 - - - 52 2,793.28 1 30.00 0 0 53 2,823 First Suffolk County.

1948 ___ 27 1,034.66 6 216.95 0 0 33 1,252 Commack, N.Y.

1949-_-_ 22 663.00 7 350.15 0 0 29 1,013

1950 --- 22 660.56 6 232.88 0 0 28 893 Bridgehampton, N. Y.

1951 __ 16 544.75 10 302.80 0 0 26 848 Cutchogue, N. Y.

1952 _-_ 13 261.12 12 790.61 0 0 25 1,052 Mt. Sinai, N. Y.

1953 _-- 8 167.43 18 989.20 0 0 26 1,157

1954 _._ 3 143.24 5 266.00 0 0 8 409

1955 _- 2 130.00 3 85.30 0 0 5 215 St. James, N. Y.

1956 __- 0 0 3 153.00 0 0 3 153 None in Nassau County.

1957 ._- 1 7.92 7 263.70 0 0 8 272

1958^-^ 2 181.00 4 322.94 0 0 6 504

1959-_-_ 1 72.00 11 629.75 0 0 12 702

1960 ___ 0 0 14 629.39 0 0 14 629

1961 0 0 10 827.63 0 0 10 828

1962 __ 0 0 2 113.00 0 0 2 113

1963 --- 0 0 6 304.95 0 0 6 305

1964 __ 0 0 7 339.62 0 0 7 340

1965-__ 1 30.00 4 116.85 0 0 5 147 Manorville, N. Y.

1966 __^ 0 0 10 382.36 0 0 10 382

1967 0 0 0 1 55 1 55 First infestation found off Long

Island.

Total 240 9,749.20 146 7,347.08 1 55 387 17,151

^ Rounded to nearest acre.

TABLE 2.—Infested land at beginning of each year, land found infested during year, land removed

from agriculture by real estate development, land treated and released for potato production,

and agricultural land remaining to be treated, Long Island, 1955-67

Year

Infested land

at beginning

of each year

Land found

infested during

year

Land removed

from agriculture

by real estate

development

Land treated

and released for

potato production

Agricultural land

remaining to

be treated

1955

1956

1957

1958

1959

1960

1961

19S2

1963

1964

1965

1966

1967

1968

Gross acres

^ 12,722.17

12,722.17

12,875.17

13,146.79

13,650.73

14,338.03

14,996.32

15,809.50

15,922.50

16,227.45

16,567.07

16,713.92

17,096.28

' 17,151.28

Gross acres

0

153.00

271.62

503.94

687.30

643.84

827.63

113.00

304.95

339,62

146.85

382.36

55.00

Gross acres

6,832.18

796.96

103.37

0

691.47

876.57

107.20

624.17

451.06

517.45

252.00

29.00

131.10

Gross acres

0

10.00

0

10.61

67.32

656,31

1,275.63

783.11

511.50

360.04

240,87

429.14

44.20

Gross acres

5,889.99

5,236.03

5,404,28

5,897.61

5,826.12

4,951.53

4,381.88

3,087.60

2,429.99

1,892.12

1,546.10

1,470.32

1,350.02

^ Cumulative figures for 1941-55. See table 1.

^Includes infestation found in Steuben Co., N. Y,
THE GOLDEN NEMATODE HANDBOOK 19

festation was detected by Plant Pest Control

Division personnel who had conducted surveys

in western New York potato-growing counties

in October and November.

Survey Procedures

The undramatic nature of the pest in its

early stages is an aid to its survival. It is very

important that the organism be recognized before crop damage becomes apparent; therefore, it is necessary that a constant alert be

maintained for its presence throughout the

potato- and tomato-producing areas of the

country. Small or isolated infestations may

exist unnoticed, since plant symptoms are not

reliable in the detection of the golden nematode. In the early stages, buildup of populations

is slow, and crop damage may not be noticeable for several years.

The most reliable method for the detection

of the golden nematode is the collection of

soil samples and the microscopic examination

of the washed residue. Yield losses are quite

evident when the concentration of cysts reach

approximately one billion per acre. However,

the presence of the golden nematode may be

detected before the concentration of the cysts

in the soil reach the level where they will

cause crop loss.

From the records of more than 100 fields of

the many hundreds surveyed on Long Island,

it has been determined that, with the survey

procedures herein outlined, cysts of the golden

nematode may be found on the average when

the concentration is approximately one million per acre. Assuming 10 viable cysts were

initially introduced into a field and there was

a tenfold increase per year, it would take approximately 6 years for a cyst population to

build up to the discovery level. Crop damage

may not become apparent for another 3 years,

during which time the cyst population may

build up to a billion per acre (fig. 8).

From this evidence it can easily be understood that a large number of cysts may exist

in a potato field in which no symptoms are

noticeable on the tops or the tubers. For this

reason nematodes may be found in a field that

has been surveyed with negative results for

several years. This is also the reason that surveys must be conducted continuously and systematically.

Survey Crew

Soil survey crews normally consist of three

or four men, one of whom is designated as the

crew leader. The number of men assigned to

survey a given property or area will vary with

the district in which they operate and the

scops of such operations. One man can survey

about 25 acres per day; therefore, the crew

may be varied from one to several men, depending upon the size of fields to be surveyed

(fig. 13).

Equipment

Each crew is provided with a map of the

area to be surveyed, a supply of No. 12 wetstrength, fungusproof, double-wall paper bags,

a felt marker or wax marking crayon, a

long-handled (28-inch) pointing trowel for

each member of the crew, wire staplers or tape

for sealing the bags, a bristle brush for cleaning shoes and equipment, and forms on which

to record field survey operations (fig. 14).

Field Soil Sampling

Upon arrival at the premises to be surveyed,

the crew leader should look over the property

and determine the boundaries, size, and shape

of the field, and plan how the field will be

surveyed. If the owner or operator has not

been previously contacted, the crew leader

should do so before beginning work.

It is advisable to divide the field into several

small subdivisions or working units. With such

subdivisions, it will be possible to return to a

given unit to pinpoint an infestation should

cysts be found in the sample. They also permit

a systematic survey of the field and give the

laboratory soil samples of proper size for processing.

In the initial survey, the field is divided into working units of approximately threefourths to one acre each. The survey is usually

conducted in a grid pattern ; about a tablespoon

of soil is collected on the end of the trowel

about every eight paces. This procedure is

BN-29989

FIGURE 13.—Survey crew collecting soil samples.
20 AGRICULTURE HANDBOOK 3 53, U.S. DEPARTMENT OF AGRICULTURE

commonly referred to as the 8x8 block

method. By this method, one composite sample

weighing 4 to 6 pounds will be collected from

every three-fourths to one acre of soil inspected.

If a more intensive survey is desired, soil is

collected on a 4 x 4 pace interval. By this

system, four times the volume of soil will be

collected as by the 8x8 pace method.

For a still more intensive survey, soil may

be collected on a 2 x 2 pace interval. By this

procedure, 16 times the volume of soil will be

collected as *by the 8x8 pace method. The

4x4 and 2X2 pace methods of survey are

generally used for pinpointing an infestation

following the initial discovery by the 8x8

pace method or for collecting samples for viability purposes following field soil fumigation.

SPIRAL

NOTiBOOK 3 TROWELS BRUSH

itiuuyinnnnnnrsu

TAPE

TK\'"Vl-^Á

k^M

^^^^4^

y \\:^-

^M^ä^

ÀX\-_

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MAP

â A A

^ ^

3 FELT

MARKERS

BAGS CLIPBOARD

FIGURE 14.—Soil survey equipment: Notebook; pointing trowels; bristle brush for cleaning shoes and equipment; tape for sealing bags; felt markers; map of area to be surveyed; No. 12 wet-&trength fungusproof,

double-wall bags; and record forms.
THE GOLDEN NEMATODE HANDBOOK 21

N-9204

FIGURE 15.—Plant root examination for nematode cysts.

Plant-Root Examination

The following method of examining potato

roots for nematodes may be used to advantage

under certain conditions. The best time is

while the nematodes are in the white or orange

stage. On Long Island this is about the last 2

weeks in June. The cysts are generally in this

stage when the potatoes begin to blossom.

Fields are looked over carefully, and patches

showing plants with weak, spindly stems and

stunted tops are selected. Plant-root examination should also be made around buildings or

where grading debris has been disposed of. The

plant is carefully removed from the ground

with a pointing trowel. The roots are separated from the soil, but no attempt is made to

remove soil that is clinging to individual roots,

as unnecessary handling causes the nematodes

to fall from the roots (fig. 15). With the aid of

a hand lens, the root system is examined carefully for female cysts. Specimens collected in

this manner are placed in vials containing 15

percent formalin or equal parts of rubbing

alcohol and water, labeled, and sent to the

laboratory for determination.

Labeling and Recording

It is very important that samples be properly labeled and adequate records prepared

to clearly identify the samples from each property inspected. Each sample should be labeled in such a manner that all information is

visible after the bag has been sealed (fig. 16).

The inspector's collection number, which consists of his initials followed by a number, is

recorded on the top of the sealed bag. For example, the first collection made on a survey in

the calendar year is No. 1. Each collection

thereafter, regardless of the State or county,

is numbered in a series for the same calendar

year. Thus, the inspector's first collection appears as "RAL-1," his second collection "RAL2," and so on throughout the year. The name

of the farmer, the map designation, or the

field number is placed on the second line. The

date is recorded in the lower right-hand corner

of the bag. As the samples or bags of soil are

collected in a given field, they are also numbered in a series beginning with No. 1. On the

last sample in a series from a particular farm,

the notation "End" is made following the

sample number.

The collected soil sample is only as good as

the records kept of its origin. Thus, in addition to labeling the collected sample another

important step in any survey is good recordkeeping (fig. 17). If the collected sample is

found in the laboratory to contain golden nematode cysts, one should be able to return to

the location in the field from which the

sample came. A field survey form should be

kept and it should include all necessary details,

such as the date sample was collected, collection

number, acres surveyed, number of samples

N-38185

FIGURE 16.—An important job of the survey crew is

to see that bags are properly labeled.
22 AGRICULTURE HANDBOOK 35 3, U.S. DEPARTMENT OP AGRICULTURE

collected, survey pattern—that is, 8x8, and so

forth—name of farm operator, mail address,

field location including map designation (if

any), State, county, and the names of the

inspectors that collected the samples (fig. 18).

On the reverse of the survey form a sketch

should be made of the field, showing the property location, definite landmarks, and the location in the field from which each sample was

collected.

Sanitation

Every reasonable precaution should be taken

to prevent the spread of this organism. Vehicles

assigned to a survey should not be permitted

to enter any property. They must remain on

highways or thoroughfares, and must be kept

clean at all times (fig. 19). Trowels must be

free of soil collecting recesses and grooves and

should be cleaned when taken from a field.

The inspector should clean his shoes with a

N-38191

FIGURE 17.—A sketch should be made of the field to show the property location, land marks, and location in the

field from which each sample was collected.
PPG 5-12

U.S. Department of Agriculture A.R.S. Plant Pest Control Division

CYST NEMATODE SURVEY

SOYBEAN I 1 OTHER

10^'£l__ 3^-32 B

MAP DESIGNATION. ^' r-/

COLLECTION NO.

ACRES SURVEYED

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26

NO. SAMPLES COLLECTED 34

SURVEY PATTERN

FARM OPERATOR <^0/^A/ PO^

/0Û msTSi^/Fom M MAIL ADDRESS ^^ „ ,„. A.,r^ A/á. COB HJfST Sr^^C/e/fLAUf.

FIELD LOCATION (cU/t/^TûU

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INSPECTORS êiMMlLz.JM££-

Initialfpf Confirmatory{ | Delimitingj |

KIND OF SURVEY

PLANT

SOIL I [

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DETERMINED BY

NO. OF

CYSTS

DATE /2/Í i^r

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 63 £9 Í?

^£5 0 ^ Ö

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TYPE OF CR0F(3) OK PROPERTY

ESTIMATED ACREAGE OF EACH

STATUS OF FIELD AT TIME OF SURVEY.

REMARKS

26 A^^S Of^ FoTATOBS

H^^l/£JTeP <^

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FIGURE 18.—(Left) Front of Plant Pest Control form PPC 3-12 used for recordkeeping in nematode survey. (Right) Back of form PPC 3-12,

showing how form is used to identify samples collected from a farm.

CO
24 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

N-38189

FIGURE 19.—All vehicles must remain on highways or

thoroughfares.

brush when he leaves fields or storage houses

(fig. 20).

Laboratory Procedures

Procedures outlined for recovering nematode

cysts from soil samples are based on the fact

that dry cysts v^^ill float in v^ater. A machine

has been developed by ARS, USDA, to float

out these cysts and separate them from most

of the extraneous material. To prevent contamination, equipment is thoroughly washed

after the processing of soil samples from each

field ; shelves and racks bearing samples are

brushed and washed before being reloaded with

new samples (fig. 21) ; when infested material

is found, sieves in use at the time are replaced

until they have been thoroughly cleaned and

inspected.

Testing sieves currently in use are made

from medium-gage tin and brass screening by

tinsmiths. The sieves are 4 inches deep. The

bottom diameter is IOI/2 inches. For this purpose such a sieve is superior to the factorymade nesting type of testing sieves, because

it has a greater capacity and is more rugged.

N-38190

FIGURE 20.—Survey crews should clean shoes and equipment thoroughly before proceeding to the next property.
THE GOLDEN NEMATODE HANDBOOK 25

FIGURE 21.—Storage racks containing soil samples for processing.

Soil Processing

The identity of every soil sample must be

maintained throughout the washing procedure.

It is important that the beaker bears the same

number as the sample and that the technician

makes certain that he is washing the sample

into the proper beaker (fig. 22).

Before a sample is introduced into the soil

processing machine (fig. 23), the slow overflow valve (No. 5) is opened. This keeps the

apertures through which the water enters the

flotation tank from being contaminated and

clogged with soil. By the time the paper bag

containing the soil is opened, enough water is in

the flotation tank so that the fast acting overflow valve (No. 6) may be opened and the

soil introduced (fig. 24A). The fast valve

serves to roil and stir the soil. This action is

best obtained if the soil is poured in gradually.

The fast valve is closed as soon as material

starts to overflow into the top sieve.

Overflowing is allowed to continue until the

water runs fairly clear or until no floating

material ca" be seen on the surface. Material

clinging to the sides of the tank is dislodged

and directed through the overflow spout with

the hand spray (No. 14). The spray should be

directed laterally along the surface of the

water so it will not submerge floating particles

(fig. 24B). Material in the top sieve should be

sprayed thoroughly with the hand spray to
26 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

FIGURE 22.—Soil samples are washed and residues

placed in beakers. Identity of every soil sample must

be maintained throughout the laboratory processing.

wash cysts through to the screen below (fig.

24C). Tests have shown that cysts tend to become trapped in the coarse material in the

top sieve.

When the flotation tank is free of floating

material, it is emptied and cleaned by turning

it upside down and opening the fast overflow

valve (fig. 24D). The tank is then allowed to

pivot back to its normal position and the spout

is washed outward with the hand spray. Be

sure the tank is washed clean.

Again, the material in the top screen is

washed, using full force on the hand spray.

The screen is then held over the sink and all

surfaces washed, inside and out, with the hand

spray. Using medium force from the hand

spray, the material in the bottom sieve is

washed and then transferred to a 600-ml.

beaker until the beaker is about three-fourths

full (fig. 25A). This sieve is washed and

sprayed in the same manner as the top sieve

(fig. 25B). After each screen is washed, its

holding receptacle should be sprayed clean. The

shelf holding the beaker should also be sprayed

clean after each transfer of material to a

beaker.

The machine is now ready for the next

sample (fig. 26).

Examination of Soil Samples

The soil samples are examined to recover,

for identification, nematode cysts that may be

present (fig. 27). The equipment needed includes a microscope (binocular with 15 X

magnification), small 80-mesh sieve (about the

size of a muffin tin), examining dishes, scalpel,

forceps, needle, 50-ml. bulb syringes, 600- and

250-ml. beakers, 500-ml. metric bottles, and a

lamp (fig. 28).

Floating material, which has been transferred into 600-ml. beakers by the washers, is

poured into the small 80-mesh sieve (fig. 29).

While the material is being poured, the

beaker is rotated to clear the sides of adhering material. A scalpel is used for transferring this material into the examining dishes.

The correct amount of material per dish is

about one-half teaspoonful. Using the bulb syringe, particles adhering to the scalpel and

sieve are rinsed into one of the dishes. Sufficient water is added to float the material

near the brim of each dish. A probing needle

should be held in the free hand for use in

spreading clumps of material and for closer

inspection of cystlike objects.

A standard Syracuse dish may be used for

examining screened flotsam; however, a special plastic dish developed by personnel at the

golden nematode laboratory is better (fig. 30).

The dish is divided into three sections. Each

section of the dish is the width of the view

through the examiner's binocular microscope.

Upon completion of the examination, all

equipment is thoroughly washed to avoid contaminating the next sample. Suspect cysts are

transferred to frosted dishes or vials and identified with collection and sample numbers.

Cysts, or objects suspected of being cysts,

should be given to the supervisor. All 80-mesh

sieves that have contained positive material

must be examined under the microscope before

they are used for another sample (fig. 31).

Checking Specimens for Viability

It is necessary to determine whether golden

nematode cysts were viable at the time of collection, since quarantine and control action

may depend upon such determination. Except

for specimens originating in fields fumigated

at the level recommended for eradication, the

viability of the cysts is based on the appearance

of the larvae within. Cysts recovered from

areas that were fumigated at the approved
THE GOLDEN NEMATODE HANDBOOK 27

SOIL WASHER ASSEMBLY

1. SINK

2. REMOVABLE WASHER

3. FLOTATION TANK

4. SPOUT

5. SLOW OVERFLOW, VALVE 1

6. FAST OVERFLOW, VALVE 2

7. ADJUSTING VALVE

8. 20-MESH SIEVE

9. 60-MESH SIEVE

10. DRAINAGE BASIN AND SPOUT

11. HOSE FITTING

12. SPLASH SHIELD

13. SIEVE RECEPTACLE

14. HAND SPRAY

TOP VIEW

LEFT SIDE VIEW FRONT VIEW

FIGURE 23.—Soil washing machine.
28 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

(A) BN-28191, (B) BN-28190, (C) BN-28189, (D) BN-28192

FIGURE 24.—(A) Soil sample being placed into soil processing machine. (B) Surface debris is directed to overflow spout by hand spray. (C) Top sieves are sprayed directly with hand spray to wash cysts through to the

screen below. (D) Flotation tank is cleaned by turning it upside down and opening the fast overflow valve.
K

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(A) BN-28194, (B) BN-28193

FIGURE 25.— (A) The washed residue is transferred to a beaker. (B) Each sieve

is carefully washed after transfer of flotsam.

IS9
30 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

FIGURE 26.—The machine and all equipment is thoroughly washed after processing the last sample.

level must be examined more thoroughly to

determine whether treatment was successful.

The viability of the cysts is determined by

placing them in a drop of water on a glass

slide. With the aid of a 90-power dissecting

stereo microscope and a surgical lance or an

iris knife, the cysts are cut open and the eggs

and larvae removed. At times it is necessary

to rupture the eggs to free the larvae. This is

accomplished by placing a cover glass over the

drop of water containing the eggs and applying just enough pressure on the cover glass

with the eraser end of a pencil to free the

larvae.

In those fields where eradication treatments

have not been applied, the specimens are considered viable if the internal structure of one

or more larvae is intact and there is no indication of any breakdown. In fields where eradication treatments have been applied but the

larval specimen(s) is intact and there is no

indication of breakdown, further checks must

be made to determine that the larva is capable

of movement. As the golden 'nematode is exceptionally sluggish, it may at times take from

1 to 24 hours before any movement is noted.

Regulatory

Soon after the golden nematode was discovered in the United States, the New York State

Department of Agriculture and Markets, under the broad coverage of the State's "Agriculture and Markets Law" relating to insect

pests and plant diseases, took action designed

to prevent the spread of the golden nematode.

In 1944, the State enacted a specific quarantine

against the golden nematode. The quarantine

has been modified and amended with changing

conditions, receipt of new information, and

development of treatments (28).

The State's quarantine was drafted in consultation with USDA's regulatory officials. The

Plant Pest Control Division has been a full

partner with the State and has cooperated in

the administration and the enforcement of the

quarantine.
THE GOLDEN NEMATODE HANDBOOK 31

N-38214

FIGURE 27.—Technicians examining flotsam for nematode cysts.

N-38215

FIGURE 28.—Laboratory technician with equipment needed for detecting nematode cysts.
32 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

i

EN-30007

FIGURE 29.—Floating material is transferred from

beaker to 80-mesh sieve.

FIGURE 30.—Flotsam is transferred to each section of

the dish, and water is added for microscopic

examination.

The Golden Nematode Act

In 1948, the Federal Government, through

the Congress of the United States, announced

the Government's policy for the protection of

the potato and the tomato industries from the

golden nematode should further action become

necessary. The Government's policy was set

forth in the Golden Nematode Act, Title 7,

U.S. Code, Sec. 150-150g. The act stated, "It

is the policy of the Government of the United

States independently or in cooperation with

State or local governmental agencies and other

public and private organizations, associations

and individuals to eradicate, suppress, control,

and to prevent the spread of the pest." The

Secretary of Agriculture is empowered, either

independently or in cooperation with States

and other agencies, to make inspections, apply

suppressive measures, enforce quarantine, enforce restrictions on planting tomatoes and

potatoes, destroy tomatoes and potatoes growing in soil found infested with or-exposed to

infestation of the golden nematode, and compensate growers in areas infested with or exposed to infestation of the golden nematode

for not planting tomatoes and potatoes or for

losses resulting from destruction of crops. The

mandatory restrictions on planting or destruction of crops must be supported by similar

State authorizing legislation.

Quarantine

The following are the basic provisions of the

New York State Golden Nematode Quarantine :

1. All lands within the boundary of Nassau

and Suffolk Counties on Long Island,

the towns of Prattsburg and Wheeler

in Steuben County, and the town of

Italy in Yates County are placed under

quarantine.

2. All potatoes grown within the designated

area on "clean" land shall be packaged in

an approved paper bag or other approved

container for movement within the continental United States and Canada (fig.

32).

3. Potatoes grown on lands which become

part of a regulated area after plantingshall be packaged in paper bags or other

approved containers, restricted in movement to approved outlets and moved only

under permit, or washed in approved

manner under supervision, packaged in

paper bags or other approved containers

and shall move only under permit, or shall

be subjected to such procedures and safeguards which may be prescribed and

shall move only under permit.

4. No potatoes shall be grown on any land

known to be infested with the golden

nematode or dangerously exposed to infestation except where such lands have

received a prescribed treatment and have

been declared safe, following soil sampling, for growing potatoes.
THE GOLDEN NEMATODE HANDBOOK 33

BN-28899

FIGURE 31.—A microscopic view of golden nematode cysts in flotsam.

5. The golden nematode in any state of development may not be moved or transported except as authorized.

6. There shall be no movement of hay,

stravtf, or plant litter from regulated area

except in accordance with an agreement

and under permit.

7. Vegetable root crops, transplants, nursery stock, bulbs, corms, and tubers are

all subject to appropriate sanitation regulations or treatment when grown on

land infested or dangerously exposed to

infestation.

Potato grading stations shall be operated

under permit, which provides for the safe

disposal of grader dirt and other waste.
34 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

9. Top soil and sod shall be moved under

permit only to designated locations in

accordance with an agreement and under

permit.

10. Used farm equipment, construction,

equipment, used containers or any other

articles that may be contaminated shall

not be moved from the area until they

have been disinfested in accordance with

prescribed procedures and a permit issued.

Approved Regulatory Treatments

Portable steam generators mounted on pickup trucks are used for cleaning farm machinery. Methyl bromide may be used to fumigate

equipment, burlap bags, tools, crates, or other

contaminated materials. The following treatment schedules have been worked out for freeing materials and commodities from the golden

nematode.

FIGURE 32.—All potatoes on Long Island are shipped in nonreusable paper bags.
THE GOLDEN NEMATODE HANDBOOK 35

Type of enclosure or

material to he treated

Chamber or tarpaulins

Chamber or tarpaulins

Vacuum chamber (27 inches

sustained vacuum).

Gastight chamber (less than

10 cubic feet).

Gastight charnber (100

cubic feet or^îïore).

Gastight chamber (100

cubic feet or more).

Dry oven (preheat)

Dry oven (preheat)

Greenhouse benches or

large containers of soil.

Temperature Exposure

C F.) of

enclosure or

material

period

(Hr.)

60° or above 16

60° or above 2

60° or above 16

60° or above 3

60° or above 3

60° or above 16

221° 1

237° %

180° 1

Treatment

23 lb. methyl bromide per 1,000

cubic feet.

46 lb. methyl bromide per 1,000

cubic feet.

8 lb. methyl bromide per 1,000

cubic feet.

1 lb. methyl bromide per 1,000

cubic feet.

4.6 lb. methyl bromide per 100

cubic feet.

2.3 lb. methyl bromide per 100

cubic feet.

Dry heat.

Dry heat.

Live steam injected throughout soil mass.

The following dips have been developed for

treatment of bulbs and corms.

Commodity

Gladiolus corms, hyacinth, iris, or tulip

bulbs, and narcissus

bulbs.

Lily-of-the-valley pips

Potato tubers

Treatment

1-hour dip in 1-pct. aqueous

solution of Aaventa 46N or

0.5 pet. for 3 hr. or 0.25 pet.

for 6 hr.'

Separate bundles one from another just before treatment

begins. Without preliminary

warmup, submerse in hot

water at 118° F. for 30 min.;

follow with 5-min. drain, and

finish with 5-min. cooling dip

or hosing in tapwater.

Wash free of soil, then submerge for at least 5 min. in

water maintained at a temperature of not less than

132° F.

1 Request for registration has not been presented in U.S.A.

Compensation

To aid growers whose income was drastically cut because infestations were found on their

farms, the State of New York enacted legislation in 1946 to compensate them for withholding their lands from potato and tomato production.

Funds for this purpose were provided solely

by the State of New York until 1948 when the

Golden Nematode Act was passed by the 80th

Congress. This act authorized Federal participation in an owner-operator compensation

program. In 1948, Federal and State funds

were made available for payments to owneroperators at the rate of $150 per acre, each

cooperator paying $75 per acre. Under an

agreement, the State assumed full payment to

renters on the basis of a fair rental value as

determined by the Commissioner of the New

York State Department of Agriculture and

Markets.

In 1950, payments to owner-operators were

reduced to $120 per acre, each cooperator paying $60. In 1951, payments were reduced to $80

per acre, each cooperator paying $40. In 1952

and 1953, the payments were $60 per acre,

Federal and State Governments each paying

$30. In 1953, the State of New York and the

U.S. Department of Agriculture agreed that

the Federal Government would withdraw from

the compensation program but would increase

its participation in surveys and,certain regulatory activities. Beginning in 1954, the State

of New York assumed the total cost of the

compensation program, paying owner-operators of infested land $60 per acre.

The compensation program provided a very

useful means whereby farmers were able to

adjust farm operations. Growers were encouraged to plant their infested potato land

to pasture, small grain, or field corn. The growing of these crops entitled the grower to receive compensation; however, if he elected to

grow high-value crops, such as vegetables,

compensation payments were not made.

With the advent of the field soil fumigation

program in 1955 and the returning of potato

land to production, the need to compensate

growers no longer existed and the amount of

compensation paid to growers decreased to a

very low level.
36 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

Chemical Control

The golden nematode is one of the most difficult of all crop pests to kill by fumigation,

since the unhatched nematode is protected by

both the shell of the egg and the tough, leathery cyst wall of the female.

Many chemicals have been tested by ARS

(8, 12) and Cornell University for control

or eradication of the golden nematode {27).

The nematocide dichloropropene-dichloropropane has consistently given the most promising

results {Ji.2).

The first large-scale attempt at chemical

control or eradication of the golden nematode

was in 1946, when the soil fumigant D-D was

applied to 1,500 acres of infested land in Nassau County, N.Y. The chemical was applied

at the rate of 45 gallons per acre in a single

application. Although this application reduced

viable nematode populations to a very low

level, complete control was not achieved. The

concentration of fumigant in the upper inch

or two of the soil was not sufficient to kill

the organism at this level {39).

Scientists generally agree that the dispersal

rate of soil fumigant vapors on reaching the

soil surface increases because of lack of restraining pressure, and the organisms on or

near the surface are not exposed to toxic gases

long enough for all of them to be killed.

This factor was taken into account when

field tests were resumed by the author in 1955

{A2). (See table 3.). The same soil fumigant,

D-D, was applied, but this time at the rate of

90 gallons per acre in two applications of 45

gallons each, 10 days apart ; the soil was turned

between applications. These tests, conducted

TABLE 3.—Number of infested fields and net

acreage treated with nematocides and treated

acreage released for use, Long Island, 1955-

67

Treated with nematocides

Year Number

of fields

Net

acreage

Gross acreage

released

for use

1955

1956

1957

1958

1959

1960

1961

1962

1963

1964

1965

3

3

1

1

4

13

17

23

15

15

15

21

6

35.05

47.78

7.00

13.50

62.83

574.93

1,163.53

783.42

489.20

498.96

381.31

764.52

267.72

0

10.00

0

10.61

67.32

656.31

1,275.63

783.11

511.50

360.04

240.87

1966

1967

429.14

44.20

Total 137 5,089.75 4,388.73

over a period of 5 years, demonstrated that

the golden nematode could be controlled, and

served as the basis for the treatment program

inaugurated on Long Island in 1960 {Al) (fig.

33).

A group of farmers and businessmen representing the potato industry on eastern Long

Island inaugurated a treatment program in

1960 on potato fields exposed to infestation.

This organization, known as the Suffolk County

Agricultural Commission, was created through

the assistance of the county executive and the

Suffolk County Board of Supervisors.

The purpose of this organization is to apply

nematocides, as a preventive measure, to poFiGURE 33.—Applying nematocide to infested field on Long Island.

N-3817S
THE GOLDEN NEMATODE HANDBOOK 37

tato fields exposed to infestation but in which

no infestation can be detected.

Many growers have multiple farming operations. Upon the discovery that one of these

fields is infested, all the other fields farmed

with the same machinery are classified as exposed to infestation. Certain potato fields in

close proximity to known infested fields may

also be classified as exposed.

The nematocide Vidden D applied in a single

treatment at 45 gallons to the acre is used.

The treatment program is supervised by a representative of the New York State Department of Agriculture and Markets and the

Agriculture Department of the Suffolk County

Extension Service. The program is "financed

from funds available through county and local

sources. A total of 2,226 acres of exposed land

was treated from 1960 through 1966.

Research by Cornell University nematologists has shown that the chemical 1,3-dichloropropene, 1,2-dichloropropane, and related hydrocarbons (80 pet.), and methyl isothiocyanate (20 pet.), marketed under the trade name

Vorlex, is effective against the golden nematode.

When applied in a split application of 10 gallons each for a total of 20 gallons per acre,

Vorlex results in nematode control equal to D-D

and Vidden D applied in a split application of

45 gallons each for a total of 90 gallons per

acre.

Vorlex, like D-D and Vidden D, is a corrosive material, and natural or synthetic rubber

tubing and gasket on applicators must be replaced with chemical-resistant materials. The

volatility of Vorlex is similar to D-D and Vidden D. Unlike D-D and Vidden D, Vorlex has

the advantage of effective nematocidal action

at temperatures as low as 40° F. However,

when the fumigant is applied at lower temperatures, 2 or 3 weeks must be allowed for the

fumigation period. At temperatures of 60'' F.

or above a fumigation period of only 7 days

is needed.

The chemical is injected into the soil at a

6-inch depth with chisel spacing on the applicator set for 8 inches. Mechanical adjustments

to the applicators are needed for this lowvolume rate.

Field tests are being conducted with Vorlex

during 1968.

Chemicals To Be Used

A chlorinated propane-propylene mixture—

consisting of chlorinated C3 hydrocarbons

(100 pet.), 1,3-dichloropropene, 1,2-dichloropropane, and related compounds—is available

commercially as D-D and Vidden D.

This chemical is toxic to living plants. Do

not apply it within 18 inches of planted crops.

The fumigant is toxic to humans and animals

if they are exposed directly to it. However,

there is no hazard to animals or human health

and no residue will result on crops when the

chemical is applied as directed on the label.

The fumigant is highly corrosive to metals,

particularly aluminum, magnesium, or their

alloys. Rubber or rubber-based hoses cannot

be used with this fumigant. Only chemicalresistant plastic tubes should be used. Applicators should be thoroughly cleaned of all

fumigant before storage. The system should be

flushed with equal parts of lubricating oil and

kerosene.

Dosage,—Ninety gallons (900 lb.) of approved fumigant per acre (1 gal. weighs 10 lb.)

should be applied in two equal treatments of

45 gallons (450 lb.) each, 10 days apart.

Seasonal limitations,—Fields are normally

fumigated in the summer and fall and are not

available for potato planting until the following spring. This permits the chemicals to

dissipate so that toxic amounts will not injure

plants or impart off-flavor to tubers and other

root crops.

At least 2 months should elapse after the

90-gallon treatment before any crop is planted.

A longer period may be necessary if there is

much rain following treatment or if the soil

temperature drops.

The soil should be fairly moist but dry

enough to be tillable. If a ball of soil barely

holds its shape when compressed in the hand,

its moisture content is acceptable for treatment. Do not apply the chemical when the soil

is too wet or too dry.

The temperature of the soil at the time of

treatment must be at least 60° F. Best results

are obtained at temperatures of 70° and above.

Since the air and soil temperatures seldom

coincide, temperature readings should be made

several inches below the soil surface US),

Equipment Needed

The following equipment is needed to prepare a field for treatment: General farm-type

tractor, disk cultivator, moldboard plow

equipped with coulter and jointer, and spiketooth harrow or pulverizer.

The disk cultivator is used to chop stubble

and stalks before plowing or to break up clods

after plowing. The harrow and pulverizer follow the plow and prepare the seedbed.

To apply the fumigant, the following equipment is needed: (1) A tractor with dual rear

wheels, (2) a shank-type applicator with either

(3) a gravity-flow system or (4) a variable
38 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

%' .miüíBr.r^-iía'.

"^ » ,' .;. . _"-.>>.'.A'..,- . "^JÍ

-K

FIGURE 34.—Additional equipment, such as platform lift for moving drums of chemical, is useful.

N-38184

displacement piston pump to move and meter

the fumigant to the shank outlet, and (5) a

furrow sealer (figs. 34, 35, and 36).

(1) The tractor used for applying the

fumigant should have sufficient power to operate without difficulty at a minimum of 3

m p.h. The tractor should be equipped with a

standard three-point hitch, dual rear wheels,

and two 50-gallon spray tanks mounted forward of the rear wheels.

(2) The shank-type applicator presently

used in the golden nematode program was originally designed for application of liquid fertilizers. It is composed of a toolbar on which

nine spring standards are mounted. Forwardswept shanks and rearward-swept shanks are

available; they are interchangeable on the

spring standards. The standards should be

spaced so that the shanks are 10 inches on

centers. A No. 1 integral tool carrier, clamped

to the toolbar, permits attaching the applicator assembly to any tractor equipped with a

three-point hitch and hydraulic lift control.

(3) The gravity-flow system of moving

and metering the liquid fumigant to the shank

outlet utilizes a specially vented tank and flowcontrol coils. This unit eliminates the need for

small restricting orifices and pressure pump,

and because of the open system, it is less apt

to clog. An overflow of the liquid at the vacuum
THE GOLDEN NEMATODE HANDBOOK 39

FIGURE 35.—Individual drums of chemical may be moved with a boom mounted on pickup truck.

N-38198

N-B9104

FIGURE 36.—The soil fumigant is rapidly transferred

from barrels to tractor by use of an air-cooled

gasoline engine.

brake fitting on the assembly will indicate a

clogged shank outlet. An instrument panel can

be constructed and placed in view of the tractor operator; the panel will indicate immediately a clogged flow line.

(4) The variable displacement piston

pump is driven by a trailing ground wheel, or

by a sprocket attached to the axle of the tractor (fig. 37). The trailing wheel has wider

utilization and is preferred. The liquid is

pumped through a flow divider, which distributes the material equally to all discharge

lines (fig. 38). Irregular speeds of the tractor

do not cause improper discharge; the trailing

wheel operating the pump compensates for

irregular rates of speed.

(5) It is necessary to seal the furrows

made by the shanks and to smooth the soil

surface to prevent uneven diffusion of the soil

fumigant. The selection and use of a sealer will

depend on the types of soil being treated. A

Scotch harrow or a suitable drag is attached to

the tractor or toolbar and towed behind the

unit to smooth and seal the furrows opened

by the shanks (fig. 39).

In sandy loam soils on Long Island, a fulllength Scotch harrow is used to effect a satisfactory seal.

In fine-textured soils, it may be necessary to

use a spike-tooth harrow to obtain the desired

seal.

(6) To avoid skips or excessive overlap-
40 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

FIGURE 37.—Tractor applicator, showing shanks and ground wheel that operates variable displacement piston

pumps. The wheel compensates for irregular speed of tractor and results in even discharge of chemical.

ping in application, the tractor operator should

use a row marker as a guide. The row marker

is attached to the toolbar.

Calibration of Fumigant Metering

Systems

Gravity-flow system.—The gravity-flow system can be calibrated by using the following

tabulation to determine the milliliters of fumigant per shank for the desired application :

Fumigant required'

Speed Ml. per min.

2.0 miles per hour 573

2.5 miles per hour 717

3.0 miles per hour 860

3.5 miles per hour 1,003

4.0 miles per hour 1,147

Milliliters required per shank per minute for 45

gallons of fumigant per acre—10-inch shank spacing.

Example: For a 45-gallon-per-acre application

with shanks spaced 10 inches apart and the

tractor traveling at 3 miles per hour, a flow of

860 milliliters of fumigant is required per

shank per minute.

Fill the tank on the applicator approximately half full of fumigant. Make certain the

filler cap is screwed on tight so that air cannot enter the tank. Open the control valve and

permit the system to run until air can be heard

gurgling through the liquid in the tank.

Quickly place a suitable container under one

of the shanks for 1 minute, then quickly remove it. Using a graduated cylinder divided

into milliliters, measure the amount of fumigant collected. If the amount is less than that

specified on the chart, lower the coil flow boom

assembly. If the flow is too great, raise the assembly. Continue taking 1-minute samples of

the flow until the proper flow rate has been

obtained. If the application rate is greater or

less than required, the tractor speed may be

changed to provide the proper dosage. If this

is not practical, another set of flow regulating

coils may be installed. Longer coils will reduce

the flow rate and shorter coils will increase it.

Variable piston pump system.—The variable

displacement pump is calibrated by changing

its piston stroke. The piston stroke adjustment
THE GOLDEN NEMATODE HANDBOOK 41

N-69118

FIGURE 38.—The chemical passes through the flow divider, which distributes material equally through each shank.

jp¿í2?e«rír ig^

N-59111

FIGURE 39.—Tractor applicators working in tandem. Scotch harrow pulled by each tractor seals the furrows

opened by the shanks.
42 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OP AGRICULTURE

is conveniently located on the side of the

pump.

Calibration of the piston pump system is

simplified by using the John Blue Company LF

Pump Setting Chart,^ Blue Part No. LF-416-

B. Use the front side of the computer only, as

the information on the back does not apply to

this installation. For this treating machine, the

loaded radius of the whepl is 13.5 inches and

the sprocket ratio 3 to 1. With the nine shanks

installed, 10 inches on centers, the swath is

90 inches. These three values v^ill alw^ays remain the same for this machine, unless a different size of tire is used, a shank removed, or

the spacing of the shanks changed.

Using the LF Pump Setting Chart, set the

loaded radius 13.5 inches opposite the sprocket

ratio, 3 to 1. Set 90 inches on the swath width

scale, and under the arrow read the pump setting opposite gallons per acre.

Since loaded radius, sprocket ratio, and

swath will remain the same, the pump setting

for any application can be read without changing the computer.

It is possible that tires mav slip. Therefore,

it may be desirable to check the calibration by

moving the machine a known distance and

measuring the output.

To check the calibration under actual travel

conditions after the preliminary pump settings

have been made, use the calibration table for LF

piston pump applicator in table 4.

TABLE 4.—Rates of flow for specified applications of fumigant

GaUons per Flow requirements for 90-inch swath

acre for distance of 100 feet

Gallons Ounces Milliliters

1 0.0172 2.201 65.1

5 .0860 11.005 325.5

10 .1720 22.01 651.0

20 .3440 44.02 1,302.0

30 .5160 66.03 1,953.0

40 .6880 88.04 2,604.0

45 .7740 99.04 2,929.5

50 .8600 110.05 3,555.0

60 1.032 182.06 3,906.0

For other application rates and other distances of travel, compute as follows: Length

in feet x rate in gallons oer acre X 0.651 =

volume of output in milliliters.

Each applicator is equipped with a calibration tank and gage. The gage is graduated in

ounces. Refer to table 4 to determine the ounces

of fumigant required for a particular application rate. Fill the calibration tank to the zero

''Chart available from John Blue Company, Hunts^

ville, Ala.

mark on the gage and close the valve to supply

tanks. Place the applicator in the ground to

normal working depth and drive it a measured

distance of 100 feet. Read the gage to determine the amount of fumigant that was released.

If 45 gallons per acre is the desired application

rate, the gage should indicate that 99.04

ounces were used in 100 feet. Change the pump

setting, if necessary, to release this amount of

fumigant in 100 feet of travel.

Field Operations for Shank Injection

Equipment

When shank injection equipment is used to

apply the nematocides, four separate and distinct field operations are necessary:

1. Preparation of the soil for first application.

2. First application of the fumigant.

3. Preparation of the soil for the second

application.

4. Second application of the chemical.

Preparing soil for first application.—Each

field to be treated must be inspected to determine the type and amount of preparation that

will be necessary before applying the chemical.

If coarse stubble or stalks from a previous

crop or weeds are present, they must be thoroughly chopped or disposed of either by decay

or by other means. Normally, it requires about

6 months for stalks and stubble to decay to a

degree that will not interfere with the application. If the field is disked thoroughly and

turned in the fall, it should be suitable for

treatment the following spring or summer—

with an additional disking and plowing just before treatment.

The type of soil, depth of top-soil, and the

normal depth of previous cultivations must be

considered when plowing the field. Normally,

a depth of approximately 8 inches is sufficient

for preparing the soil for treatment. If the soil

has been plowed previously to a depth greater

than 8 inches, then the soil must be plowed to

that depth in preparation for treatment.

Preparation of the soil for the first application of the chemical will usually require the

following operations to condition the soil for

reception of the chemical:

1. Disked one or more times, depending on

trash present.

2. Turned with a moldboard plow to a depth

equal to maximum penetration in past

cultural operations. Do not plow when

soil is too wet or too dry.

3. Disked lightly to smooth ridges and clods.

The soil is ready for treatment when it has
THE GOLDEN NEMÁTODE HANDBOOK 43

been properly plowed and is relatively loose to

permit maximum diffusion of the chemical,

when it is free of ridges, clods, and debris,

and when it contains sufficient moisture to be

tillable.

First application of fumigant,—The fumigant should be applied immediately after the

soil conditioning operation has been completed,

if the correct soil moisture and soil temperature conditions prevail.

The entire area must be covered with fumigant ; skips mav result in failure. When all the

field has been fumigated, make one or more

round trips at each end to insure treatment of

as much of the headlands, turnaround and

other border areas as possible.

Make sure that the fumigant is flowing continuously to each shank. If clogging occurs,

stop immediately and make adjustments. When

the trouble has been corrected, turn the tractor

around and re-treat all the area that may not

have received proper treatment. When lowering the shanks into the soil, keep the tractor

moving to prevent clogging the flow line outlet with soil.

Preparing soil for second application,—At

least 10 days should elapse after the first application before preparing the soil for the second

application. As a result of the first application,

the texture of the soil is usually in a more

suitable condition for treatment. The soil is

turned with a moldboard plow at a depth of

1 to 2 inches deeper than the first plowing. The

moldboard plow must be equipped with a suitable coulter-jointer for this operation. The

coulter-jointer is adjusted so that the top 3-

inch layer of soil is cut and turned into the

bottom of the furrow and covered with the

lower layers of soil. This is most important

since the fumigant dissipates rapidly near the

soil surface, and cysts occurring there during

the first treatment may not be exposed to a

lethal dose.

A frequent check should be made in the

second plowing operation to determine if the

top 3 inches of soil are properly turned and

covered. This can be accomplished by spreading a 6-inch band of lime on the surface of the

soil in advance of and at right angles to the

plow (fig. 40). After the plow has passed, dig

into the turned limed area to determine

whether the lime has been covered to the required minimum depth of 3 inches (fig. 41).

The soil surface should be comparatively

smooth after this operation. If it is not smooth,

a harrow, drag, or roller should be employed.

In any event, the soil should not be disturbed

below a depth of 3 inches.

Second application of fumigant,—The second application of fumigant is made 10 to 14

days after the first. The same procedure and

technique is used as in the first application.

It might be desirable to make the second application at right angles to the first. This will result in a checkerboard treatment of 10-inch

squares. The topography of the field will determine which direction to make the second application.

Treatment of border areas.—Any golden

nematode cysts remaining along the border of

treated fields serve as a potential source of

reinfestation. Accordingly, on Long Island the

chemical sodium iV-methyldithiocarbamate,

sold commercially as Vapam, is applied to

headlands, roadsides, farmyards, and farm

roads adjacent to fields that have been fumigated. The object is to kill the nematodes on

the soil surface. The Vapam is mixed with

water and applied as a drench at the rate of

50 gallons of Vapam in approximately 3,000

gallons of water per acre. Since Vapam is most

effective when the soil surface is moist, it is

generally applied after a rain. Any apparatus

affording high gallonage and low pressure can

be used. A boom-type nozzle has been found

most practical.

Decontamination of Equipment

All equipment used in the preparation or

treatment of an infested field, must be thoroughly disinfected before it is moved from the

field to another location. The equipment should

be subjected to the prescribed cleaning procedures using steam or methyl bromide fumigation (fig. 42).

Precautions

If pesticides are handled or applied improperly, or if unused parts are disposed of improperly, they may be injurious to humans,

domestic animals, desirable plants, and pollinating insects, fish, or other wildlife, and may

contaminate water supplies. Use pesticides only

when needed and handle them with care.

When using nematocides, follow the manufacturer's directions exactly. Variations in soils

and climate may affect the action of the

nematocides.

Handle nematocides with extreme care. Avoid

prolonged breathing of the fumes. Do not allow the liquid to come into contact with the

skin. If the liquid is accidentally splashed on
44 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

_ N-38175

FIGURE 40.—A 6-inch band of lime is placed on the surface of soil to check efficiency of plowing operation.

N-38178

FIGURE 41.^ Inspection of the plowed ground determines whether the lime has been covered to the required

minimum depth of 3 inches.
THE GOLDEN NEMATODE HANDBOOK 45

N-38183

FIGURE 42.- -All equipment used on infested land must be thoroughly steamed clean or fumigated before it is

moved to another location.

clothing, including gloves or shoes, remove the

garments without delay; do not wear them

again until they are washed, cleaned, or at

least thoroughly aired for a day or two. Never

risk getting the material in your mouth. If it

is splashed in your eyes, wash it out with large

quantities of water and consult a physician.

Keep children and pets away from fumigated

soil. Potting and rooting soil that has been

treated with nematocides should not be used

until all traces of fumigant odor have disappeared.

Careful disposal of empty pesticide containers and surplus pesticides is an important part

of safe pesticide use. Large metal drums can

be disposed of more safely and easily by returning to the supplier or selling them to a

cooperage firm equipped to handle toxic materials. Small metal drums should be rendered

unusable by chopping holes in them or crushing them and then burying them at public

dumps.

Resistant Potato Varieties

The potato is one of about 2,000 species in

the family Solanaceae. This family includes

such plants as tobacco, tomato, eggplant, pepper, horse-nettle, bittersweet, ground cherry,

and petunia. Botanically, the potato cultivated

in North America, Europe, and other lands is

Solanum tuberosum L. (fig. 43). There are

nearly 160 wild species and 20 cultivated

species of the tuber-bearing Solanums. All
46 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

Flower—

Deve

Eye

(rudimento

i-Terminol leoflet

pules

roots

on tuber stolon

Distal end

proximal end

über

FIGURE 43.—Diagram of the parts of a potato plant. Note that the stolons and tubers arise from stem tissue,

and the true roots arise at the base of the stem.
THE GOLDEN NEMATODE HANDBOOK 47

these relatives of the potato are of New World

origin. Probably the closest wild relative is

S. andigenum Juz. & Buk., which produces acceptable yields under the short-day conditions

of the Andes Mountains. Some botanists

consider S. andigenum to be a subspecies of

S. tuberosum.

A potato breeding program to find resistance

to the golden nematode has been carried out

extensively in Great Britain, Holland, and

Germany, since 1945 when Ellenby, a British

scientist, screened many Solanum spp. and discovered that S, vernei and S. tuberosum spp.

andigena were resistant to the golden nematode

(50, p. 252). In the United States, Cornell

University scientists confirmed Ellenby*s findings and, in addition, found that S.^sucrense

also had resistant characteristics. However,

andigena seem to offer the best basis for a

potato breeding program because the resistance of andigena potatoes is due to a single

dominant gene (38, p, 265). A breeding program for resistance involves backcrossing,

which is not too involved in this case because

no sterility barriers exist between andigena

and S, tuberosum. Furthermore, since potato

varieties are reproduced vegetatively there are

few problems in fixing the resistance in varieties once it has been transferred from the

resistant parent (88, p. 265),

Resistant varieties, like susceptible ones,

produce a substance that has a high hatching

quality. The roots are invaded by the larvae

of the nematode in a manner similar to that

of larvae invading susceptible varieties. Some

males are produced, but few females complete

their development to form cysts. Thus, the

growing of resistant potatoes on infested land

results in a decrease of nematode populations

in the soil (38, p, 265),

Until the 1950's it was assumed that there

was no particular physiological variation in

the golden nematode's ability to attack the

resistant host (20, p, -ílJ^), However, in breeding varieties for resistance to the golden nematode, it has been shown that within the

nematode species there exist populations with

ability to break the resistance and complete

their life cycle on the resistant variety. These

populations are referred to as resistance

breakers or resistance-breaking biotypes (20,

p, 4-14). Scientists investigating resistant

potatoes in Europe found that the golden

nematode from Peru was capable of breaking

resistance in 82 Dutch tuber lines bred from

C.P.C. 1673 (20, p, ^li). The names of biotypes are not yet established; however,

European workers report that they have obtained evidence of at least six biotypes (38,

p, 265).

The widespread occurrence of biotypes in

several European countries presents serious

problems for maintaining potato varieties that

are resistant to the golden nematode. S. vernei

-is resistant to all known biotypes; however,

plant breeders have found this species difficult

to use in a breeding program. The resistance

of S, vernei is thought to be due to many

genes, some of which may be lost in backcrosses of cultivated varieties (38, p. 265),

In the United States, both the U.S. Department of Agriculture and Cornell University

have programs seeking to develop nematode

resistant potatoes. Since the work started

(about 1950), these agencies have tested

thousands of new potato lines. In February

1966, a new commercial potato variety resistant to the golden nematode was announced.

The new variety, named Peconic (fig. 44), is a

product of the work of Cornell plant breeders

and plant pathologists.

Peconic compares favorably with the

popular Long Island variety Katahdin (fig. 45).

Peconic is free of defects such as hollow heart

and misshapened or oversized tubers. Peconic

has been tested and found to be resistant

against the race of golden nematode occurring

in Newfoundland, Canada (32).

Peconic derives its resistance to the golden

nematode from the subspecies andigena.

Resistance-breaking biotypes that are capable

of breaking resistance of this type occur in

Europe. There is no evidence to date, however,

that more than one form of nematode exists

on Long Island. The andigena resistance is

effective against the golden nematode on Long

Island (32).

In expectation that resistance-breaking biotypes might be developed, plant breeders are

conducting research with other species of

Solanum to find other sources of nematode resistance. In the meantime, the growing

of Peconic as a commercial variety will be

restricted to infested potato fields that have

been fumigated and released to growers for

potato production. Peconic may also be used on

land exposed to infestation but on which the

nematode population has not developed to a

level that can be detected by the usual survey

procedures.

Thus, the future control program of the

golden nematode on Long Island will be soil

fumieration of all known infested fields followed by the use of resistant potato varieties.

Peconic is expected to be ready for limited

use on Long Island in 1968.
48 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

BN-30080

FIGURE 44.- -Peconic, a new variety resistant to the golden nematode, was released February 1966. Peconic has

many of the same characteristics as the Katahdin.

^fcpFIGURE 45.—Tubers of the Katahdin variety.

BN-30077

This variety is widely grown on Long Island and the Atlantic coast.
THE GOLDFN NEMATODE HANDBOOK 49

BN-32356

FIGURE 46.—Wauseon, a new variety resistant to the golden nematode, was released November 1967. Wauseon

is also similar to the Katahdin.

USDA plant breeders, in cooperation with

Cornell scientists, released in 1967 a second

variety resistant to the golden nematode. The

new variety named Wauseon is a selection from

a cross between B4159-8 and Katahdin. It is

resistant to common scab, moderately resistant

to Verticillium wilt, highly resistant to the

common races of late blight, resistant to latent

mosaic and mild mosaic, and to the golden

nematode. Its tubers are resistant to net

necrosis following leafroll infection. The tubers

of Wauseon have smooth skin, are round to

oblong, and have shallow eyes and creamywhite flesh (fig. 46).

THE INTERNATIONAL PROBLEM OF CONTROL

The golden nematode is a pest of global concern (figs. 47-51). It is frequently the subject

of both domestic and international regulations.

The international spread of the golden nematode is a target of import regulations of many

countries.

The long-distance shipment of nursery stock,

plants, plant parts, corms, and tubers is increasing. The use of air transport to move

these products has multiplied the risk of longdistance spread of not only the golden nematode but other insects and plant diseases.

Effective nematocides, such as dips for nursery stock, bulbs, corms, and tubers are urgently needed. The hazards of spreading

nematodes are not restricted to plant material

alone, as will be seen later in this chapter.

Most countries that have regulations against

the golden nematode require that imported

agricultural products be free of soil. Most

countries have very strict regulations about

the importation of potatoes from countries

where the nematode is known to occur. Many

countries require a phytosanitary certificate

showing that the potatoes originated in fields

that have been soil sampled with negative results or from a portion of the country where

all survey data indicate that the nematode

does not exist. In some instances, potatoes are

embargoed from countries where the golden

nematode occurs. The movement of bulbs,

corms, and nursery stock is usually subject to

rigid requirements.

The need for uniform measures concerning

the control of the golden nematode has been

recognized by the European Economic Community (EEC). On October 14, 1966, the EEC

Commission submitted proposals to the EEC

Council for consideration and adoption.

These proposed regulations were the mini-
50 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

0-v,0i

-0:7

¿>^

CANADA

VANCOUVER ISLAND^ ^NEWFOUNDLAND

UNITED STATES • STEUBEN COUNTY, N.Y.

'LONG ISLAND

WESTERN HEMISPHERE

•INFESTATION

PANAMA^

PERUX •

BOLIVIA

CHILE)

ARGENTINA'

FIGURE 47.—Golden nematode infestations in the Western Hemisphere.
THE GOLDEN NEMATODE HANDBOOK 51

"U"

Û

rISRAEL

CANARY

ISLANDS^

ALGERIA

WEST

ASIA

AFRICA

•INFESTATION

FIGURE 48.—Golden nematode infestations in Africa and West Asia.

mum requirements for the control of the

golden nematode and prevention of its spread

in member countries. The council recommended

that seed potatoes be produced only in areas

that have been carefully surveyed and officially

declared free of the golden nematode. Upon

discovery of an infestation, member countries

will conduct such surveys as necessary to find

the limits of the infestation. Member countries

will prohibit the growing or storage of potatoes

or plants for transplanting on infested

premises. Member countries will prescribe that

potatoes recognized as being contaminated

with the golden nematode shall not be used for

seed purposes.

These regulations should remain in effect

until a determination is made that the nematode no longer exists. The council also recom-
52 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

WESTERN EUROPE

COUNTRY WITH INFESTATION

^1[CELAND-/^

FAEROE IS

NORTHERN f ^SCOTLAND

IRELAND^ ELAND ' \^ I

r^^ ŒNGLANI

IRISH) M J\ •'J

REPUBLICL/WALES \ <^

CHANNEL IS.gr^

PORTUGAL; { SPAIN

FIGURE 49.—Golden nematode infestations in Western Europe.

<f -^ "<=->à-,^

^

^ EASTERN EUROPE

AND THE U.S.S.R. ^^'^^'^^'^"^^'"^-w ^o INFESTATION» ^—y7<-^

là^'^jj^ • U.S.S.R.

>*rVPOLAND

{•EAST GERMANY

*ttCZECHOSLOVAKIA

^<cr»YUGosLÂvi^ rv o

^^.n^^

^''^¡tfc^^"^^./-r^ "£ f^\^

FIGURE 50.—Golden nematode infestations in Eastern Europe and the U.S.S.R.
THE GOLDEN NEMATODE HANDBOOK 53

FAR EAST

AND OCEANIA

•INFESTATION

U ^

h

FIGURE 51.—Golden nematode infestations in the Far East and Oceania.

mended that stricter or supplementary regulations be enacted to control or prevent the

spread of the golden nematode where local

conditions warrant.

The EEC Commission will publish before

November of each year a list of resistant potato

varieties and the biotype of nematode against

which the resistance applies.

The European and Mediterranean Plant Protection Organization, Paris, France, generally

referred to as EPPO, has been the leader in

Europe in establishing guidelines to be followed in preventing international spread of the

nematode {34-, p. 29). The golden nematode

was the subject of a special conference

sponsored by the EPPO in the Netherlands in

1955. At that time the member countries recommended requirements for export certification of potatoes. The conferences also recommended the use of a standard soil sampling

technique based on the Dutch and United

Kingdom methods, which are widely used in

European countries (17). (See Appendixes II

and III.)

To avoid possible importation of the golden

nematode into the United States, the Nursery
54 AGRICULTURE HANDBOOK 3 53, U.S. DEPARTMENT OF AGRICULTURE

Stock, Plant and Seed Quarantine No. 37 requires that plant propagative material be free

from sand, soil, or earth, except shipments

from those areas in Canada known to be free

from this pest. Otherwise, such importations

may be refused entry into the United States.

As an additional safeguard, such restricted

plant material from those countries with official systems of inspection shall be accompanied

by a certificate issued by a duly authorized

foreign official attesting that such material

was grown on land in which no golden nematode is known to occur. In countries where the

golden nematode is reported, the certificate

shall state the date of the most recent inspection of the land in which the restricted plant

material was grown. The Federal Plant Pest

Act also prohibits the importation of soil that

might be associated with any material, such

as farm machinery and used bags, and the

Federal potato regulations prohibit the importation of potatoes from most foreign areas.

The enforcement of various Federal plant

quarantine regulations results in the interception of the golden nematode each year on a

wide variety of products and materials. During

1965, the golden nematode was intercepted

more than a hundred times: In soil mailed

from Ireland ; in soil with automotive equipment: (fig. 52) ; in bagging, conex box, and

tractors (fig. 53) in cargo from England, Germany, and Italy; in soil with horseradish in

air mail and in ships' stores from England and

an unknown origin; in soil with potatoes in

air baggage, cargo, and ships' stores from

England, France, Germany, Italy, Netherlands,

Peru, Scotland, Sweden, and unknown origin;

in soil with propagative material in air baggage, air mail, air quarters, baggage, and

cargo from England, Finland, France, Germany, Ireland, Italy, Poland, Portugal, Scotland, Sweden, and an unknown origin; in soil

with shamrock in air baggage, air cargo, and

mail from Ireland; and in soil in ships' stores

from England and Germany.

BN-22749

FIGURE 52.—USDA Plant Quarantine inspectors check a returning tourist's car for golden nematode. Contaminated equipment must be steamed clean before entry into the United States.
THE GOLDEN NEMATODE HANDBOOK 55

BN-28128

FIGURE 53.—Although reconditioned and painted, these tractors from Europe were contaminated with golden

nematode. Cysts were found on small particles of soil under the paint.

WORLD DISTRIBUTION OF THE GOLDEN NEMATODE

Algeria

In March 1953, symptoms of golden nematode damage became apparent near Algiers. A

survey was made of all potato- and tomatogrowing areas in the vicinity of Algiers. This

was a plant-root survey with some soil samples

taken. Eight communes in the vicinity of

Algiers were found infested. This is a coastal

zone where often two and sometimes three

successive potato crops are grown in one year

on the same field. Accordingly, several periods

of cyst formations are observed from March

to December.

About 1,900 hectares (4,750 acres) of winter potatoes (harvested March to May) and

930 hectares (2,325 acres) of summer potatoes

(harvested November and December) are produced in this area. The country produces approximately 10,700 hectares (26,750 acres) of

' Information contained in this chapter was prepared

on the basis of reports of foreign governments, reports

of U.S. agricultural attaches, EPPO reports, results of

office research, correspondence, and related information.

winter potatoes and 13,500 hectares (33,750

acres) of summer potatoes.

In certain communes where infestations are

heavy, potato production has been reported to

be reduced 50 percent, from 130 to 150 quintals

per hectare to 50 quintals per hectare (from

28,660 to 33,069 lb. to 11,023 lb. per acre).

Regulations are in effect for the movement

of commodities capable of carrying the pest.

There has been some decrease in the intensity

of the infestation. This decrease is attributed

to the general application of soil treatment,

mainly with D-D but also with products of the

Vapam type, which were officially approved in

Algeria in 1960. A decree of September 6, 1954,

stipulated that all soils used for nurseries must

first be examined by the Plant Protection Service. The decree has since been amended limiting this requirement to horticultural nurseries

growing vegetables.

A decree of February 17, 1961, regulates

the importation of plants and plant products

that might carry the pest.

The National Institute of Agronomical Research is conducting studies of the nematode.
56 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

Argentina

The following summary of the golden nematode situation in Argentina (fig. 54) is based

on a translation of a report by Dr. Enrique

Brücher (S):

"In our discussions with North American

and European colleagues on the biological relationship between Heterodera rostochiensis

and the South American Solanaceae, we have

always been of the opinion that the center of

origin or natural habitat of the parasite should

not be far from regions of a wide genetic and

physiological diversification of the generic

group Tuberarium (the tuber-bearing species

of the genus Solarium) and from places where

we have collected carriers of genes of natural

resistance against this nematode.

"As we have explained in a previous preliminary publication (Brücher 1960), it must

be supposed that the true origin of this nematode would be South America and, more precisely, the high valleys of the boundary zone

between Argentina and Bolivia. All our

searches for years in the northern Provinces

for the purpose of finding in the soil of the

wild tuberous species of Solanum, cyst of the

golden nematode, were in vain until for the

first time, in February 1955, in the high valley

of Purmamarca (Province of Jujuy) we observed protuberances on roots of a wild species

of Solanum which appeared to be caused by

the ß"olden nematode.

"We passed years in doubt, until on the occasion of the ^International Expedition of

Genocentros, 1958,' we had the opportunity to

confirm definitely the findings. We found thus

in the sou of Tascal at 3,600 m. alt., in the

mountainous part in the north of the Chani

Mountains, cysts typical of Heterodera rostochiensis on a wild species of Solanum (Tuberarium). Some weeks later we discovered other

foci of infection in the eastern part of the

Department of Tilcara in a valley leading from

Abra Remate (4,000 m. high) to Durazno, and

another in a valley in the north of the Cierro

Sisiler (4.700 m.).

"In both cases the cysts of Heterodera rostchiensis were found in humus where Solanum

acaule, S, gourlayi, and S. alticolum were numerous. In the findine: at the Valley Durazno

there were small patches with S, vernei in

abundance, also, S, infundibuliforme, S. acaule,

S, alticolum, and an undetermined species in

the environs and, besides, abandoned plantings

of native potatoes. The finding at the Valley

Durazno was sent for definite confirmation to

the Istituut de Nematologia de Holland, our

determination being affirmed by the Director,

Dr. Oostenbrink, in a letter dated January 24,

1959. We are convinced that with adequate

survey and personnel training, many more

natural foci in wild species of Solanum (Tuberarium) could be discovered in the Provinces

of Salta and Jujuy.

"But the proof of the existence of these

minute cysts on roots in the sou is a task

difficult enough when one is not adequately

prepared. Therefore, one must suppose that the

distribution of the golden nematode must be

much greater in northern Argentina than our

casual findings indicate.

"There is not the least doubt that the great

potato-growing region of Argentina (south of

the province of Buenos Aires) is equally

threatened by this enemy of the potato."

Austria

The golden nematode was first found in

Austria in 1940 and is known to occur in six

of nine Provinces; namely, Vorarlberg, Salzburg, Upper Austria, Lower Austria, Carinthia, and Styria. The extent of distribution of

the potato root eelworm is not exactly known

because regular soil examinations are carried

out only in the seed-potato-producing areas

(fig. 55).

Existing provincial plant quarantine legislation provides sufficient legal authority for the

adoption of measures to control the golden

nematode. To contain the spread of the nematode in Austria, the Federal Institute for Plant

Protection has worked out recommendations

for growers to follow.

If soil surveys reveal an infestation level No.

Ill (see Appendix II), a minimum of 5 years

should elapse and the field should again be soil

sampled before potatoes are planted. At level

No. IV there is an added requirement that the

entire potato crop of the affected farm be examined each year until the outbreak is wiped

out. At level No. V the farmer should be made

to discontinue potato production until the outbreak has been greatly reduced. In home

gardens and on small plots or in mountain locations where rotation or chemical control is

impracticable, resistant potato varieties are

recommended. In areas devoted to seed production with infestation levels No. Ill and IV

and where the level is No. V, the use of suitable

nematocides, preferably in combination with

the single-time use of nematode-resistant potato varieties, is recommended.

The resistant potato variety Antinema and

the varieties Apis, Amelio, and Amaryl are

being grown in Austria.
THE GOLDEN NEMATODE HANDBOOK 57

BRAZIL

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FIGURE 54.—Infested areas in Argentina and Bolivia.
58 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

FEDERAL REPUBLIC OF GERMANY

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FIGURE 55.—Infested provinces in Austria.

Belgium

The golden nematode was first found in

Belgium in 1949. Belgium prohibits growing

potatoes and tomatoes on the same land more

often than once every 3 years. On infested

properties the law prohibits the growing of potato, tomato, and other vegetable plants for

transplanting for a period of 5 years. This

period can, however, be lengthened or shortened depending on circumstances, such as

viable cyst count. The law requires that early

potatoes be harvested no later than June 20.

On the Belgium coast where commercial potatoes are grown, the Government has a soil

treatment program using D-D at the rate of

approximately 63.4 gallons per acre. The Plant

Protection Service has a systematic soil sampling survey throughout the country. All samples are processed at Ghent. Studies are

underway to determine whether resistancebreaking races occur.

Bolivia

The following description of the golden

nematode situation in Bolivia was summarized

from a report by Frank H. Bell and B. Alandia

Segundo (í).

During the period 1952-54, observations were

made on the diseases of potatoes in Bolivia

that should be of interest to pathologists elsewhere, especially since the area may be one of

the ancestral homes of the potato.

One of the more interesting organisms noted

for the first time in Bolivia was the golden

nematode, Heterodera rostochiensis. It was

found to be widespread in the Lake Titicaca

region of northwestern Bolivia, at an altitude

of 12,600 to 13,000 feet (fig. 54). One of the

sites where it was noted was on the famous

"Island of the Sun" of the prehistoric Incas.

It was also found in the Tunari range (altitude

11,000 feet) near Cochabamba. This latter site

is 200 miles southwest of Lake Titicaca in

mountains that are separated from the main

Bolivian Altiplano. The widespread occurrence

of this nematode in long cultivated, heavily

populated regions of Bolivia substantiates the

theory of Ing. de Segura of Peru, where the

nematode was noted in 1952 for the first time,

that this nematode is indigenous to the Andes

and was probably carried from there to Europe

and then to the United States. The root-knot

nematode, Meloidogtjne sp., has been found on

potatoes in the sandy soils of the Island of the

Sun, and in the highlands east of the Cochabamba Valley.
THE GOLDEN NEMATODE HANDBOOK 59

Canada

The golden nematode was first discovered in

Canada in the Province of Newfoundland iii

October 1962, in the community of Manuels on

Conception Bay some 14 miles west of the city

of St. Johns. The discovery of the pest was not

entirely unexpected because no import restrictions were maintained by the colony until 1949,

when Newfoundland became a Province of

Canada. Potatoes and other vegetables were

imported from Great Britain when the necessity arose, and it is possible that the nematode

was introduced many years ago.

The importation of potatoes into Canada

from Newfoundland has been prohibited since

1910 because of potato wart. Following the

confederation with Canada, the regulations

under the Destructive Insect Pest Act were

amended to continue the prohibition of the

movement of potatoes, soil, plants with soil,

used bags, and other items, and to prohibit

their export to other countries.

The Canada Department of Agriculture's

Plant Protection Division, under the authority

of the Destructive Insect and Pest Act and the

Destructive Insect and Pest Regulations, has

broad power to prohibit or restrict the importation of plants with soils or packing materials,

containers, machinery, implements, vehicles,

and other carriers containing soil or to which

soil may adhere. This applies to all countries

except the continental United States unless

plants with soils have been thoroughly washed

or otherwise treated immediately before movement into Canada and unless the importation

is accomüanied by an affidavit or declaration

to that effect.

Canada has been particularly alert for the

presence of the golden nematode in the country

because of the importance of seed-potato exports. Canada produces annually about 70,000

acres of seed potatoes on nearly 10,000 fields in

nine Provinces. A random survey, started in

1959, has been conducted throughout the seedproducing areas.

On June 16, 1965, a potato farmer on Vancouver Island, Saanich Peninsula, near the city

of Victoria, British Columbia, brought to the

Saanich Peninsula Agricultural Experiment

Station a potato plant with soil for examination by the pathologist. The plant and soil were

examined by W. R, Orchard and N. Waseem

and found to contain a large number of golden

nematodes in various stages of development.

Specimens were sent to Ottawa for confirmation, which came on June 21.

The infested property belonged to a farmer

who had formerly grown bulbs. He had imported bulbs from Europe and had grown the

last crop of bulbs on the infested property in

1938. Between 1938 and 1950 he grew various

crops and since 1950 he had continuously

grown potatoes on the field (fig. 56).

The Canada Department of Agriculture's

Plant Protection Division took immediate steps

to regulate the movement of crop plants and

commodities that might carry the nematode

out of the area. In consultation with the author

of this handbook, a program to combat the

nematode was developed. A laboratory was established, surveys instituted, and quarantine

regulations established.

By 1966, surveys conducted throughout the

Province of British Columbia showed that the

golden nematode was confined to a small area

on the Saanich Peninsula. Cysts of the golden

nematode have been found on approximately

150 acres.

All infested lands are removed from production and fumigated with dichloropropenedichloropropane at the rate of 50 imperial gallons per acre. At least two applications are

given each field. In addition, some 300 acres

exposed to infestation have been removed from

potato production and fumigated. The Canadian Government compensates growers for

their losses.

Canary Islands

According to a report bv R. Chamberlain,

University of Belfast, and luan Valladares

Barbuxano, they discovered the golden nematode in La Victoria de Acentejo and in other

districts in Tenerife, Canary Islands, on December 27, 1960 (6). According to Chamberlain, the discovery was made at latitude 28° 25'

north. This appears to be the most southern

occurrence as yet recorded of H. rostochiensis

in the Old World. (See Spain.)

Chile

In October 1966, the Minister of Agriculture, Santiago, Chile, telephoned me and advised that a shipment of 3,500 metric tons of

Irish potatoes from Europe were in port and

had been found to be contaminated with the

golden nematode. Safeguards were discussed

and aerreed upon for the safe disposition of the

potatoes. All the potatoes, except a few bags,

were washed and sold for consumption in

metropolitan areas. The unwashed potatoes

were later moved to a farm. In December 1967,

I was advised that representatives of the De-
o

,J»

TFIGURE 56.—The original infested field on Vancouver Island, British Columbia. The property had previously grown

bulbs imported from Europe. The farmer first noted stunted potato plants in 1964. When this photograph was made

by the author on June 23, 1965, the entire field showed evidence of damage.

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THE GOLDEN NEMATODE HANDBOOK 61

partment of Defensa Agrícola had inspected a

farm in an isolated valley in Aconcagua Province, where the potatoes had been used for

seed, and had confirmed the presence of the

golden nematode.

Czechoslovakia

The golden nematode was first recorded in

Czechoslovakia in 1954.

Infestation in Czechoslovakia consists mainly

of isolated pockets in private gardens where

crop rotation is not properly observed. The

intensity of attacks is low. Infestations occur

in Bohemia and northern Moravia. The Government regulates growing of potatoes and

other host crops on infested land. This regulation prohibits growing of other host crops on

infested land for 5 to 7 years, requires crop rotation, and severely restricts the utilization of

potatoes grown in infested communes. Imported

potatoes are carefully inspected. The Quarantine and Plant Protection Service enforces Decree No. 1, 1959. Research is being conducted to

detect biotypes of the nematode.

Denmark

The golden nematode has been known to

exist in Denmark since 1928. The State Plant

Pathology Institute examines soil samples for

cysts of the golden nematode in connection

with the certification of seed potatoes and

other plant products for export. Sampling in

potato fields and examination of soil samples

for cysts comply with the approved international rules.

Only a few attacks of the nematode are

found annually in cultivated agricultural land.

Most of the infestations observed from 1964 to

1966 were in the northern part of Jutland

(fig. 57).

In certain contaminated areas, mostly gardens, series of samples have been investigated

to determine the degree of infestation and stop

the spread of the nematode to adjoining seedpotato fields. Growing of potatoes on infested

land is prohibited for a number of years under

regulations of the State Plant Protection Service.

Potato growing has been prohibited for

many years in nurseries. Most nurseries have

been found free of the nematode. Areas where

the nematode has been found are under frequent observation and production is controlled.

Analysis of samples from these areas are the

basis for deciding whether potatoes and nursery plants may be grown there.

Altogether, the Government's Plant Protection Service has recorded infestations in 25

counties, as follows:

No. of infestations

Private gardens 106

Commercial cultivated agricultural

land 160

Commercial horticulture and gardening _ 37

Under systematic investigations 64 agricultural holdings, where the Government's Plant

Protection Service had recorded potato root

nematode from 1956 to 1964, were investigated

to determine if the pest had spread to other

fields. The purpose of this investigation was to

test the Protection Service's usual practice of

recording only the affected areas on individual

holdings. The investigation showed that 61 percent of the holdings where the nematode had

been recorded in one part had newly infested

parts.

In Denmark the work of producing varieties

resistant to the golden nematode has been very

intense, and it is expected that commercial

varieties will be available for growers on a

limited scale by 1969. These investigations are

conducted at the Potato Improvement Research

Station in Vandel. The testing is done at the

State Plant Pathology Institute at Lyngby.

Investigations over the past 3 years (1964-

1959-63

FIGURE 57.—Occurrence of the golden nematode on

potato farms in Denmark.
62 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

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FIGURE 58.—Test plots showing the effects of golden nematode on tomatoes at Imperial College field station,

Sunninghill, Ascot Burkes, England.

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BN-30076

FIGURE 59.—A potato field in England, showing heavy damage caused by golden nematode. [British Crown

Copyright; reproduced by permission.]
THE GOLDEN NEMATODE HANDBOOK 63

66) have been carried out to see if resistancebreaking biotypes can be found. None have

been found to date.

The use of soil fumigants is primarily on the

Amager island southeast of Copenhagen where

there is a heavy concentration of vegetable

farming. The nematocide D-D is used at the

rates of 45 to 60 cubic centimeters per square

meter for fumigating soil in greenhouses. In

cultivated fields 400 to 500 liters per hectare

(about 21/2 acres) of D-D is used. The cost of

fumigating one hectare in 1966 vs^as about 1,500

kroner ($210).

The Government's Agriculture Advisory

Service strongly recommends to farmers that

do not have infested land a sound rotation

program of at least 2 to 3 years for potatoes.

England and Wales

The golden nematode in England and Wales

was confined to Yorkshire in 1917, but it had

probably been present for 10 to 15 years before

that time. It is also reported that the nematode

was causing damage to tomatoes (fig. 58) in

Yorkshire as early as 1928.

According to Southey (38 pp. 171, 173, 17^.),

the nematode is well-distributed in the warepotato districts of the country. Because of the

demand for potatoes during World Wars I and

II, the problem was compounded. Southey reports that following World War II the potato

acreage rose nearly to the one million mark,

and complete or partial crop failures were frequent. In 1949, a conservative estimate was

made by the Ministry of Agriculture that losses

caused by the golden nematode were about 2

million pounds sterling, or equivalent to about

$10 annually on each acre of potatoes (fig. 59).

Despite the situation, England has been

fortunate in that the golden nematode is rare

in the main seed-producing areas (fig. 60).

Surveys are conducted by the Ministry of Agriculture as an advisory service to growers. The

Ministry of Agriculture, through the Extension Service, has advised growers on the importance of long rotations, especially in areas

where the nematode populations are light.

After commercial damage appears in a field,

the Ministry of Agriculture advises the farmer

to leave it out of production for 6 years or

longer to be sure that no economic damage to

crops will occur. The Ministry of Agriculture

then recommends potato producing on a 1 year

out of 5 rotation.

FIGURE 60.—Distribution of the golden nematode on

commercial potatoes in England and Wales.

Paeroe Islands

The first report of the golden nematode in

the Faeroe Islands was in 1951 when K. Lindhardt {2A) examined 15 soil samples and

found they were all infested. In 1964, another

survey was made of the Islands, and 19 of 93

samples collected were found to contain cysts.

The golden nematode may have existed in

the Islands before 1940, but it is more likely

that this pest was introduced from Great

Britain during World War II on supplies for

troops. Several infested soil samples from the

Islands were found to contain an aggressive

biotype that attacks varieties of potatoes containing resistance of Solanum tuberosum subspecies andigena. Aggressive biotypes are not

uncommon in Scotland and some parts of

England, but they have not been detected in

Denmark.

Although the Ministry of Agriculture of

Denmark issues regulatory orders to control

the golden nematode, plant diseases, and insect

pests, the orders do not apply to the Faeroe

Islands.

Potatoes are produced on about 150 hectares

(375 acres). Since soil suitable for growing

potatoes is limited, some fields have been in

potato production for more than 100 years.
64 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

Finland

The golden nematode was first reported in

Finland in 1946. Nematode surveys are systematically conducted in the country by Tuhoelaintutkimuslaitos, Tikkurila. Infestations are

confined to the southern part of the country

and do not extend beyond the region of Tampere (61°40' N.) (fig. 61).

Finnish Government regulations prohibit

the growing of potatoes on infested land from

3 to 5 years. Resistant varieties are available.

The most common variety in use is "Antinema."

Approximately 2,500 kilograms (5,511 pounds)

FIGURE Gl.^Infested areas in Finland.

of this variety have been distributed to farmers.

Research is being conducted on the golden

nematode problem. Biotypes A, B, C, and D

have been discovered.

France

The golden nematode was first reported in

France in 1947.

A Ministerial Order, dated November 15,

1963, and published in the Official Gazette of

November 27, 1963, page 10597, sets forth the

requirements for control of the potato root

eelworm throughout the country. The main

provisions are restrictive measures, including

systematic soil sampling of areas surrounding

fields in which the pest has been recorded by

the Plant Protection Service; prohibition of

the growing of seed potatoes on infested soil

for 5 years ; if infestation exceeds a prescribed

level, prohibition also of growing ware potatoes, tomatoes, and all crops for transplanting ;

prolongation of prohibition for further 3-year

periods until samples confirm absence of pest;

and directives for the use of underground parts

of all crops growing or ready for harvesting in

the zones in which restrictions apply.

The intensity of the attack of the nematode

varies greatly in different regions. Severe attacks have not occurred in recent years because

soil examination is made of fields and when

infestations are found to exceed an acceptable

level the growing of host plants is prohibited

for 5 years. Resistant varieties of host plants

are also being tried. In fields where infestation

is particularly heavy, total prohibition of host

plants is necessary. A race of golden nematode

that broke the resistance of the potato variety

Antinema has been found in Saint Malo.

Germany (East)

The golden nematode is widely distributed

in East Germany. The infestations are most

numerous on sandy soil, and for economic

reasons potatoes have been grown too frequently. Most communes of the country are

infested. In some areas between 2 and 3 percent of the total agricultural area is infested.

However, in the northern area (Mecklenburg

and Brandenburg) the averages occasionally

are as high as 8 percent of the agricultural

area.

East Germany also uses resistant potato

varieties. Regulations are enforced on crop

rotation and the movement of infested commodities. Soil examination of fields is made to
THE GOLDEN NEMATODE HANDBOOK 65

determine when infestations exceed an acceptable level, whereupon the growing of host

plants is prohibited for 5 years. Rotation of

potatoes and tomatoes is compulsory. Through

these measures, intensity of attack is kept at

low levels.

Rules governing marketing are contained in

a decree published June 29, 1963, in the

Gesetzblatt II.

on potato nematode

Republic is (a) the

1956, Prevention of

Germany (West)

It is from Germany that we first learned

about the potato nematode problem. (See History and Origin of the Golden Nematode.)

There are no official figures on the extent of

distribution within the German Federal Republic, although it is known that the potato

nematode occurs in all States. After a considerable postwar increase in nematode incidence,

the infestation intensity decreased especially

in recent years mainly because an increase in

the standard of living (and associated decline

in demand) had caused a decrease in potato

cultivation.

The basic legislation

control in the Federal

Ordinance of July 20,

Occurrence and Control of Potato Nematodes,

and (b) Ordinance Amending the Ordinance

on Prevention of Occurrence and Control of

Potato Nematodes of July 26,1961.

According to these ordinances, the production of potatoes and tomatoes as well as the

construction of dirt storage pits is, on principle, forbidden in infested areas until the Plant

Protection Service has declared the areas to be

free of infestation (fig. 62). On the basis of

these ordinances, the States have established

implementing ordinances, which consider any

special local conditions in their areas.

The breeding of nematode-resistant varieties

of potatoes is being pursued with great vigor.

The Federal Variety Agency (Bundessortenamt) has acknowledged that three varieties

are resistant against nematodes: Antinema,

Apis, Cobra.

In several localities of the Federal Republic

there occurs the resistance-immune biotype B

of the potato nematode. It is expected that

further resistance-immune biotypes will be discovered.

As a matter of principle, the Government

does not interfere with crop rotation on noninfested areas. Farmers are advised, however, to

plant potatoes and other nematode host plants

only every third year. If an area is considered

to be endangered with infestation, the authori-

/Ichtung!

FIGURE 62.—Poster used by West German extension

service to alert farmers to the golden nematode

problem.

ties may order that potatoes can be planted

only every third year.

The growing of potatoes on infested land is

basically forbidden. Upon application, the Government may grant exemptions—for example,

for the growing of resistant varieties; for

noninfested parts of fields, provided these

parts or neighboring fields are not endangered ;

for scientific and breeding purposes, provided

this does not endanger nematode control.

The Plant Protection Offices inspect their

areas for the occurrence of potato nematodes

and other pests. All enterprises producing for

export (horticultural enterprises, tree nurseries) are ofiicially inspected periodically for

noninfestation ; for example, in North RhineWestphalia the total area is inspected every 4

years and the ground storage places every 2

years. Similar regulations exist in the other

States.

Before seed potatoes can be grown, an official inspector must declare the area free from
66 AGRICULTURE HANDBOOK 3 53, U.S. DEPARTMENT OP AGRICULTURE

infestation. In addition, random sample inspections for nematodes are carried out in

areas considered to be in danger of infestation.

Greece

The golden nematode was found in Greece

for the first time in 1951 in the mountainous

area of Parnon Arkadia (2),

The golden nematode was found in 11 locations administratively belonging to the prefectures of Arkadia, Messinia, Boeotia, Serres,

Larisa, Chalkidiki, and the Cyclades islands

(Paros, Naxos) after research was carried out

by the Benachi Phytopathological Institute.

The Ministry of Agriculture has since reported

six locations belonging to the prefectures of

Elis, Lakonia, Imathia, Lasythion, and the

island of Aegina.

The above areas are not entirely infested by

the nematode but are limited to spots of up to

500 square meters. Infested areas where potatoes are grown are estimated to be about

30,000 to 50,000 stremmas (7,410 to 12,350

acres). Total area of potato production is about

480,000 stremmas (118,560 acres).

The Ministry of Agriculture recommends to

the growers the use of nematocides, which

lately are being used on a growing scale. Furthermore, where an infestation has been observed in seed-potato-producing centers, the

Ministry of Agriculture requires compulsory

washing of seed potatoes with special equipment.

Generally, to control the spread of the nematode and protect the potato crop, a rotation is

recommended. Relevant instructions have been

issued by the appropriate service of the Ministry of Agriculture.

Nematocides recommended for the control

of the golden nematode in Greece are D-D soil

fumigant at the rate of 100 to 200 kilograms

(220 to 441 pounds) per acre and ethylene

dibromide at the rate of 40 to 100 kilograms

(88 to 220 pounds) per acre.

There are no resistant potato varieties.

The cultivation of potatoes in infested areas

is not legally prohibited, but the Ministry

strongly recommends that such fields not be

used for potatoes.

Seed-potato-producing centers are immediately abolished upon the finding of the nematode.

Guernsey

The golden nematode was first reported in

Guernsey in 1952.

Infestations are now fairly widespread

throughout the island of Guernsey. Any apparently new infestations usually indicate a

sudden local increase in the pest population as

a result of cropping potatoes 2 or more years

in succession. Some control measures using

D-D are proving highly successful.

Iceland

The golden nematode was first detected in

Iceland in 1953. Its presence is limited to a

small area in the Westman Islands, and in two

small villages on the southwest coast of Iceland—Eyrarbakki and Stokkseyri.

During August and September, roots of potato plants are examined to determine the

extent of the infestations. Technical agricultural experts are available in each of the counties, and they endeavor to keep informed on

agricultural developments. Kesistant potato

varieties are not considered suitable for Icelandic soil conditions, and chemical fumigants

are not used because they are too expensive.

Resistance-breaking biotypes are not known to

be present.

Although the Government has no special

regulations concerning the rotation of potatoes

on land not known to be infested, it advises

producers of the desirability of rotating crops.

Growers are also advised by the Government

ofiicials not to plant on infested fields.

India

The golden nematode was first identified in

India in 1961 and is thought to be restricted

to certain areas in Nilgiri Hills of Madras

S^ate (fig. 63). Intensive field surveys to determine the distribution of the golden nematode

in Madras State have been in progress since

1963. The first round of surveys was expected

to be completed by June 1967. A total of 946

acres out of 24,000 acres of potato-growing

area has been found to be infested.

Research on the problem is in progress under

the direction of the Indian Council of Agricultural Research at Ootacamund (Nilgiri Hills,

Madras) in collaboration with the Central Potato Research Institute. Research includes

search for biotypes, experiments with resistant

potato varieties, testing of soil fumigants, and

a study of the effect of 1-, 2-, 3-, and 4-year

rotation of nonhost crops.

The question of imposing a domestic quarantine against the golden nematode in the infested area is under consideration. The growing

of potatoes on infested land is not recommended. Under the Destructive Insect and Pest

Act, 1914, the importation of potatoes is pro-
THE GOLDEN NEMATODE HANDBOOK 67

FIGURE 63.—Infested areas in India.

hibited except in small quantities for research

or scientific purposes.

Ireland

Distribution of the golden nematode in Ireland appears to be limited although the nematode has been known to be present since 1922.

Infestation occurs mainly in pockets of land

in districts that were once congested (bogland

and hillsides), where a rotation of crops was

not feasible under the land tenure system of

the 19th century. Most of this land is no longer

cultivated. Golden nematode also is frequently

found in urban and suburban gardens following poor rotational practices.

The Destructive Insects and Pests (Consolidation) Act of 1958 sets forth regulations

concerning the golden nematode. This act em-
68 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

powers the Minister of Agriculture and Fisheries to issue various orders. One of these is

the Potato Root Eelworm Order of 1951.

Potato varieties resistant to the golden

nematode are available in Ireland only for research purposes. No such varieties are available commercially.

Chemical fumigants are not used against the

golden nematode on outdoor crops grown in

Ireland. However, Dazomet (methyl-iso-thiocyanate) is used to control the golden nematode

in tomatoes grown under glass.

Farmland found to be infested with golden

nematode must be sown with grass immediately

in accordance with the Potato Root Eelworm

Order. The Department of Agriculture and

Fisheries does not consider it practical to extend this requirement to urban garden plots

because of the frequent changes in occupiers.

But when the golden nematode is found in urban gardens, the owner is advised to sow the

garden with grass, and he is given a copy of

the Department's leaflet "Potato Root Eelworm.''

Surveys to date indicate mostly biotype A

occurs in Ireland, Only one population of biotype B has been found. No other biotypes have

been found.

Ireland has no legislation controlling the

rotation of crops. Rotation of seed potatoes

is controlled, however, under the Government's

Certified Seed Potato Scheme, and several

Irish companies using potatoes for industrial

purposes include rotation clauses in their contracts with growers. The Irish Sugar Company

uses potatoes in its potato flake factory, and

Ceimici Teoranta (Chemicals Limited) uses

potatoes for making glucose. Both of these

Government-sponsored companies have rotation clauses in their contracts with growers.

Israel

The golden nematode was first detected in

Israel in 1957. A minor infestation was found

in the Raanana region, Petach-Tikva subdistrict (15 miles north of Tel Aviv) all within

a radius of 3 miles.

The Plant Protection Service of the Ministry

of Agriculture conducts systematic surveys of

all potato fields in the Raanana region. So far,

it has been unnecessary to apply Government

regulation. The Extension Service of the Ministry of Agriculture recommends one potato

crop in 3 years in the region affected by the

nematode. As a rule, farmers comply with the

advice given by the Extension Service officer

in an effort to control pests of this nature.

There are no resistant potato varieties available and no resistance-breaking biotypes are

known. Some experimental work has been done

with soil fumigants using ethylene dibromide

at the rate of 60 liters to the acre (15.85

gallons).

Italy

The occurrence of the golden nematode in

Italy was first reported in 1962. According to

the Ministry of Agriculture, infestations are

found mainly in the Naples area where early

potatoes are grown. Some scientists think that

the infested area is much more widespread.

The Naples area has maintained fairly good

yields. This may be related to the use of cow

manure as a fertilizer, which is thought to

inhibit the development of the nematode.

At a potato conference in 1964, Government

control measures were petitioned without success. Imported seed potatoes, however, must

come from areas free of the nematode. The

Government does offer advice on control measures recommending crop rotation.

Fields in the infested area are numerous and

small. The potato crop in this area is of great

economic importance.

Research is underway on resistant potato

varieties and chemical fumigants.

Jersey

The golden nematode was first discovered on

the island of Jersey in 1938 where it was

causing serious damage to early potatoes (37).

Later that same year, the nematode was found

in a field of tomatoes.

The seriousness of the nematode has been

demonstrated in a few cases where potatoes

have yielded less than the weight of seed

planted. Tomato growers are also concerned

about the seriousness of the problem. Cases

have been reported where yields of tomatoes

have been reduced from 15 tons an acre to less

than 2 tons. Soil samples are examined for

growers on an advisory basis. In general, more

than 50 percent of the samples examined have

measurable contamination.

Soil fumigation using D-D, methyl bromide,

and Vapam is in use. Under a law that came

into force in 1962, approved materials for potato root eelworm control were subsidized. The

subsidies being granted were for soil sampling

or crop examination, or both, which show

whether the pest populations have reached the

level sufficient to cause crop damage.
THE GOLDEN NEMATODE HANDBOOK 69

Luxembourg

The golden nematode was found in Luxembourg in 1955. Potato-producing areas are surveyed for the presence of the nematode.

However, only 20 hectares (50 acres) are

known to be infested.

The soil fumigants Vapam and Nemacur

have been tested as control measures for the

nematode. Growers, if they choose to do so,

may import resistant varieties of potatoes.

Although there are no specific Government

regulations against the golden nematode at this

time, the Government wiU implement regulations developed by the European Economic

Council.

Netherlands

The golden nematode was first reported in

Holland in 1941. Regulatory action was taken

shortly after that to restrict and control the

pest. These regulations were amended in 1947

and again in 1949. A law was passed to prohibit the growing of potatoes and transplants

in infested land and to set up special precautions for the distribution of infested material.

Growing potatoes on noninfested land more

often than once every 3 years is also prohibited.

This regulation alone has had a direct effect

on the farming practices of the country.

These regulations have prevented the

buildup of the nematode and protected the

country's export of many agricultural commodities.

Protective crop rotation is strictly enforced

and has the support of farm organizations.

Potatoes grown against regulations are destroyed. Bulbs and perennials cannot be grown

on land where there is any danger of spreading

the golden nematode. Potatoes are prohibited

from being grown in the bulb-growing districts

of Holland. The towns, communities, and boundaries of areas where growing potatoes is

prohibited are specifically outlined in Government regulations.

The growing of resistant varieties of potatoes is a specific part of the Government

regulations to combat the golden nematode.

Each year the Government designates those

parts of infested districts or properties that

may be planted to varieties resistant to the

golden nematode. In 1966, a total of 3,800

hectares (9,500 acres) was planted to resistant

potato varieties. Holland's best varieties for

industrial potato are Saturna and Prevalent.

The best tablestock potato is Amaryl.

Early potatoes must be harvested before

June 26, except in north Holland where the

harvesting date is designated as July 6. Harvesting dates may vary from year to year, depending on growing conditions. Potato growers

who plant early varieties are permitted under

the law to grow potatoes on the same land

every other year.

Potatoes and tomatoes are prohibited from

being grown in the nursery stock growing area

of Boskoop.

The resistant potato varieties that are now

available to growers have a resistance to the

more common biotype A of the pest only. Growing these varieties is not permitted in fields

that are infested with other biotypes. Good

progress has been made with the development

of varieties with resistance to biotypes other

than A. These varieties are also expected to

be available commercially within a few years.

Holland has an extensive research program

at Wageningen to investigate many aspects of

the nematode control problem including biological and chemical control, potato breeding

studies for the development of resistant varieties, resistance-breaking biotypes, and other

research.

Northern Ireland

The golden nematode was found for the first

time in Northern Ireland in 1933 on a potato

crop in a garden near Belfast.

Regulations relating to the golden nematode

were first introduced in 1945, and the various

modifying enactments that followed have been

consolidated into a single measure, the Potato

Root Eelworm Order, Northern Ireland, 1960.

Under the terms of this order, the golden

nematode is a '^notifiable'' pest, and wide regulatory powers are vested in the Ministry of

Agriculture for the enforcement of the order

by such means as necessary.

A systematic survey has been in operation

in Northern Ireland for 20 years. Upon discovery of the golden nematode on any land,

certain prohibitions are enforced, such as (a)

the removal for planting purposes of any potatoes, tomato plants, or other propagating

material; the disposal of such niant or plant

products from infested land will be in accordance with directions from the Ministry of

Agriculture; (b) the removal of infested soil

from any premises whether loose or adhering

to the roots of plants, imnlements, or other

articles; (c) the planting of infested property

to potatoes, tomatoes, or plant propagating

material. These restrictions remain in force

until withdrawn by the Ministry of Agriculture. Since the first notices of infestation were

issued in 1945, there have been no instances
70 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

where resumption of potato growing has been

permitted or where any of the other requirements have been released.

Glasshouses in which infestations are found

are permitted to resume normal culture of

tomatoes or other glasshouse plants provided

such establishment can be freed of infestation

to the satisfaction of the Ministry of Agriculture. Under such situations, steam sterilization

of soil and other cleanup measures are satisfactory to eradicate infestations.

Field infestations of commercial potatoes are

for the most part confined to five districts, each

of which is designated by the Ministry of

Agriculture as a "scheduled area." These areas

embrace the infested property and a wide

peripheral zone. Withm these areas the provisions of the potato root eelworm order apply.

U. S. S. R.

FIGURE 64.—Infested areas in Norway.
THE GOLDEN NEMATODE HANDBOOK 71

FIGURE 65.—Infested areas in Panama.

In addition, special cropping restrictions require that potatoes shall not be planted on any

noninfested land in the scheduled area more

often than twice in any 8 years.

Norway

The golden nematode was first found in

Norway in 1956. The infested farms are located in the coastal counties of Aust-Agder,

Vest-Agder, and Rogaland (fig. 64).

The Norwegian Plant Protection Institute,

Norwegian Ministry of Agriculture, has issued

regulations concerning the control of golden

nematode. Regulations include the following:

Tractors that might have infested soil must be

thoroughly cleaned and washed; the sale of

seed potatoes and other plant material from

infested areas is prohibited; and the growing

of potatoes in infested areas is also prohibited.

Exceptions may be made, however, to the last

regulation under certain conditions and then

only for the growing of potatoes every fourth

year. The Norwegian Government's regulations concerning this pest are based on recommendations of EPPO, of which Norway is a

member.

The Norwegian Plant Protection Institute,

Norwegian Agricultural College, Vollebekk,

has developed two resistant potato varieties.

Nationwide surveys for the nematode are

being conducted. So far, the southwest, southern, and eastern parts have been covered by

this survey.

One resistance-breaking biotype B has been

found on one farm. Investigations on resistance-breaking biotypes are continuing.

As a protective measure, the Government

strongly recommends to growers that they rotate potatoes on land not known to be infested.

Panama

The golden nematode was discovered in

Panama in August 1967 following damage to

a potato crop. The infestation is located in

Cerro Punta, Chiriqui (fig. 65), according to

Dr. Rodrigo Tarte, University of Panama.

The main varieties of potatoes grown in the

country are Alpha, Red Pontiac, and Urgenta.

Farmers have customarily obtained their seed

potatoes from European sources.

Dr. Tarte has organized a survey which is

being conducted throughout the potatogrowing regions of the country. On October 26,

1967, Mr. Jack E. Lipes, FAO Agricultural

Officer, El Salvador, notified the Plant Quarantine Division, ARS, USDA, of the occurrences

of the infestation and indicated that OIRSA

(Organismo Internacional Regional De Sanidad

Agropecuria) was considering placing a quarantine on Panama because of the nematode.

Mr. Lipes reported that swollen females were

found on the roots of potatoes, and he sent a

vial of specimens to the USDA. Dr. A. Morgan

Golden confirmed that the specimens were H.

rostochiensis.

This is the first infestation of the golden

nematode recorded from Central America. Offi-
72 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

cials from OIRSA report that surveys will be

conducted in other Central American countries.

Peru

The golden nematode was discovered in Peru

in 1952 following United States Plant Quarantine interception of the pest at ports of entry

in 1951. (See '^History and Origin of the

Golden Nematode.")

Potato culture in Peru, represented by many

native varieties, including Solanum tuberosum

and andigena subspecies and improved hybrids,

constitutes the main agricultural occupation

along the mountain range from the border of

the Republic of Ecuador to Bolivia and Chile.

It is a vast zone in which approximately 200,-

000 hectares (500,000 acres) are cultivated,

excluding the regions near the ocean in the

Central Coast Departments.

The economic value of the potato crop is

surpassed only by sugarcane and cotton production. These crops are planted in areas near

the ocean and within a few inter-Andean valleys. In the mountain zones the potato crop is

largely affected by the endemic plague represented by Heterodera rostochiensis.

The species Solanum X curtilohum and

Solanum X juzepczuMi (sour potato type) are

immune to golden nematode. These are cultivated at altitudes of 4,000 meters.

Ing. Alberto Martin Ravines, of the Agrarian

Experimental Station of La Molina, has been

making a study of the golden nematode situation in Peru under United States funds provided by Public Law 480. Ing. Martin reports

that most of the cultivated area in the Andean

region between 2,300 and 4,000 meters above

sea level is affected. The greatest infestation

has been found at altitudes from 3,000 to 4,000

meters.

Poland

The golden nematode was first identified in

Poland (1967 boundaries) in 1946, although it

was known to have existed in the eastern part

of prewar Germany (now Poland's western

Provinces).

Poland is the second largest potato-producing

country in the world. Potato fields occupy about

17 percent of the total land in cultivated crops.

The golden nematode can be found in all

parts of Poland, but it is more concentrated in

the northern, central, western, and southwestern Provinces. A survey carried out by Professor Henryk Sandner in 1961-62 resulted in an

estimate of golden nematode incidence of 2.8

percent throughout Poland. It is also estimated

that this nematode appears in about 2 percent

of Poland's potato fields.

External quarantine regulations control the

international movement of potatoes from infected plants, and internal quarantine regulations limit the domestic movement of potatoes

from infested areas. Potatoes may be taken

out of such areas only for direct use in processing, and the vehicles used for transport must

be disinfected.

Resistant potato varieties have not been developed, but two East German potato varieties,

Sagitta and Specula, may be suitable for Polish

potato growers. There are no known resistanceIbreaking biotypes in the country. Experiments

in the use of nematocides for the control of

the nematode have been conducted by the Regional Plant Protection Stations of the Ministry of Agriculture, but the results are described

as **rather erratic."

Government regulations forbid the growing

of potatoes and tomatoes for 5 years on land

known to be infested with the golden nematode.

The Regional Plant Protection Stations of the

Ministry of Agriculture conduct systematic

surveys annually.

Portugal

The golden nematode attacks potatoes and

sometimes tomatoes in Portugal. Although its

presence in Portugal was already suspected,

it was identified for the first time in 1956 in

Serra de Nogueira, near Braganca (northeast

Portugal) by M. Neves. A more detailed study,

by Macara (26), was published in "Broteria"

in 1963. In 1958, Entrudo Junior made a study

of this pest in the region south of Lisbon.

The golden nematode is found mainly in the

areas of Beira Alta, Tras-os-Montes, and Estremadura; the latter is near Lisbon and potatoes

are grown intensively, sometimes in successive

years on the same plot (fig. 66), Information

relating to the golden nematode on tomato

plants in Portugal is scanty, but it seems that

there is danger of a buildup in the nematode

population in certain irrigated areas where

tomatoes for the canned paste industry are

being intensively cultivated, with very short

crop rotations or with no rotation at all.

The average annual area growing potatoes

and tomatoes is about 100,000 hectares (250,-

000 acres), but the golden nematode constitutes a problem in only about 10 percent of

this area, especially on sandy soils.

There are no specific official regulations in

Portugal concerning the golden nematode; the

general plant protection regulations are, of

course, applicable to this pest. An educational

campaign giving advice to the farmers on the
THE GOLDEN NEMATODE HANDBOOK 73

LISBON if

*i ESTREMADURA

CANARY ISLANDS

(Spain) (P

^ ^^TENERIFE/7

FIGURE 66.—Infested areas in Portugal and Spain.

best way to avoid damages to the crops by the

golden nematode has, however, been implemented through the agricultural extension

service.

The Plant Protection Service has tried some

resistant varieties of potatoes, but they were

not found to be satisfactory. Although the

Dutch potato variety Amaryl showed some

promise, its resistance was later shown to be

effective against only one biotype of the several

biotypes known to exist in Portugal.

Saarland

The golden nematode was first recorded in

Saarland in 1952.

All fields and produce considered to be infested are supervised by the Saarland Plant

Protection Service. If one field is found to be

infested, the rules apply to all the land of the

holding. Use of potatoes from such holdings

for seed purposes is prohibited, and these potatoes must be boiled or steamed before being

used for the table or for fodder. On fields considered to be infested, potatoes and tomatoes

must be grown only once in 3 years. Of plots

under 1,000 meters (or parts thereof if used

by different owners) not more than one-third

can be planted to potatoes or tomatoes, to allow

for proper rotation. On land that the Plant

Protection Service considers to be heavily infested, the growing of potatoes or tomatoes is

prohibited for at least 3 years. If this rule is

not obeyed, the crops are destroyed.

Scotland

The golden nematode has been common in

Scotland since about 1913. The nematode exists

in several locations in the commercial potato-
74 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OP AGRICULTURE

growing area, but there is no organized systematic survey in those areas. Field soil

surveys in commercial districts are conducted

on a request basis.

Scotland's Plant ï*rotection Service is primarily concerned with protecting the seedproducing areas. Scotland produces most of the

seed for England and several other European

countries. Careful surveys are conducted in

seed-growing districts. For "virus-tested/'

**foundation," and **stock seed" certificates, a

6-year rotation is required, together with a

precrop soil inspection and a crop inspection

during the growing season. Soil tests and crop

inspections are required for all seed exported.

If an infestation is found, the field cannot be

used for growing seed potatoes for at least

12 years.

Seed for use within the country is grown

on a 6-year rotation basis, together with a

growing-crop inspection. If the rotational requirement cannot be met, a soil inspection is

necessary. ^'Washed seed" certificates are available to growers producing seed for domestic

purposes, if their crop is found to be infested

during the crop inspection. Such potatoes must

be washed in an approved washing plant to the

satisfaction of an inspector of the Department

of Agriculture, Fisheries, and Food.

Spain

The golden nematode was first detected in

Spain in 1953 at La Maresma, Province of

Barcelona. Presumably, it originated in the

imports of foreign seed potatoes. Five Provinces bordering on the Mediterranean coastline, the inland Province of Logroño, and the

Canary Island Province of Tenerife are affected by this pest in varying degrees. The

geographical points, areas, or districts involved are the following (fig. 66) :

Province Point, Area, or District

Alicante Novelda

Barcelona La Maresma and lower

Llobregat area

Gerona S.E. tip of Province

Logroño Santo Domingo de la Calzada

TarraR'ona Cambrils

Tenerife (Canary La Orotava

Islands, 1960)

Valencia Las Siete Villas

No estimate of the overall acreage aflfected

is available. Barcelona is by far the most

heavily infested Province, The infestation covers a strip of land in the vicinity of and

running parallel to the seaboard ; the strip extends along more than one-third of the seaboard of Barcelona Province.

The Spanish Government has issued I'egulations against the golden nematode. The official

action taken includes the creation of a Nematological Section to study and implement plans

for the control of potato cultures and import

restrictions. The growing of potatoes where

the presence of the golden nematode has been

verified must be rotated ; they cannot be grown

more than once every 3 years or more. No host

plants of the golden nematode may be cultivated during the intervening period. The cultivation of seed potatoes and certain other

plantings on infested land is forbidden.

No resistance-breaking biotypes of the

golden nematode have been discovered. Surveys

for the golden nematode are being carried out

annually.

Sweden

The first discovery of golden nematode in

Sweden was made at Högsjöbruk in the western part of Sodermanland county (central

Sweden) in 1922. In 1928-32 the nematode

was found to be relatively widespread in the

northwestern part of Skane (southern Sweden).

The nematode is frequently found in the

factory-potato-growing area of southeastern

Skane and Blekinge counties, but it is also

found sporadically throughout Sweden. The

nematode is uniformly of biotype A.

The first legislation against this pest was

passed in 1932. Growing of potatoes on soil

declared as infested was prohibited, and removal of contaminated soil was required in

certain instances. When it was found that the

parasite had been widely spread and could not

be stopped, the legislation was adjusted in 1939

and again in 1962. The law is used primarily

to prevent the spread of the parasite to certain

areas growing potatoes for special purposes

(seed potatoes) and to stop the spread of

resistance-breaking biotypes.

Resistant potato varieties, principally of

Dutch origin, are available, but their use is

generally restricted to factory potatoes. A new

Swedish table variety has been developed at

the Svalof Plant Breeding Institute.

The Government has authority under the

law^ to prohibit growing potatoes on land declared as infested. This authority is applied

pï-incipally to land on which seed potatoes are

grown. Seed-potato fields are sampled before

the growing and cultivating period. Strict regulations are maintained to see that seed-potato

fields are not infested through machinery,

tools, bags, and so forth.

The Plant Protection Agency makes continuous surveys and also samples soil from potatoes
THE GOLDEN NEMATODE HANDBOOK 75

delivered to starch factories. On infested properties, growers are requested to apply a rotation to potatoes ; they are not to grow potatoes

more often than every 3 years in southern

Sweden and every 4 years in northern parts of

the country. Available nematode-resistant varieties of potatoes are recommended for use,

Switzerland

The golden nematode was found in Switzerland in 1958. Areas reported to be infested

in Switzerland are located in the Orbe Plain

and near Murten. Other locations include the

mountainous cantons of Graubunden, Ticino,

and Valais. Although 132 hectares (330 acres)

in 8 cantons are known to be infested, the

infested lands are small plots in high altitude

valleys where potatoes for domestic consumption have been grown continuously. The degree

of infestation is rated as EPPO code III and

IV.

The golden nematode is considered a particularly dangerous pest in Switzerland. Government legislation, dated March 5, 1962,

concerning plant protection, set forth regulations for the control of the pest.

Comprehensive surveys in all fields in the

seed-potato-growing areas are made. All potentially affected areas are surveyed every 4

years. The surveys are organized by the Plant

Protection Department and the Seed Breeding

Society. Survey results are evaluated at the

national level by the Swiss Seed Breeding

Society.

The growing of host crops, seedlings of any

kind, and nursery stock is strongly forbidden

on infested land for 4, and in some places 8,

years. No soil or refuse can be removed from

areas under restrictions. In protective zones,

host plants must not be grown more often than

every 4 years. There is a special prohibition

for exporting host crops and root crops that

have been grown in a protective zone.

Switzerland is not breeding resistant varieties but obtains resistant potatoes from other

foreign sources. Quantities available, however,

are not sufficient to meet needs. Resistancebreaking biotypes have been found. Experiments are being conducted for the control of

the nematode with nematocides. Through the

agricultural extension service, particular emphasis is placed on advising growers to carry

out sound crop-rotation practices.

Union of Soviet Socialist Republics

The potato nematode in the U.S.S.R. was

first discovered in 1948 in the Lithuanian Republic. The nematode was discovered in Latvia

in 1949 and Estonia in 1953 (fig. 67),

Separate and isolated centers of infection of

the potato nematode have been discovered in

other western regions of the Russian Federated Soviet Socialist Republic, mainly on the

personal plots of collective farmers and market

gardens of workers. The potato nematode has

been discovered in rare instances in the fields

of collective farms, state farms, and other

government enterprises.

Aggressive biotypes of the potato nematode

have not been found in the U.S.S.R.

A quarantine system of the areas infected

with the potato nematode was implemented,

and the contamination has remained insignificant. In 1965, the contaminated area consisted

of 0.04 percent of the total potato area in all

categories of farming, and the economic loss

from the potato nematode was of no practical

significance.

In the U.S.S.R. a broad investigation of

potato areas is annually carried out with the

purpose of discovering new centers of potato

nematode contamination.

The main means of combating potato nematode are quarantine arrangements; namely,

control and restriction of transportation of potatoes, fodder roots, onions, and other bulbous

plants from areas under quarantine for the

potato nematode; strict observance of rotations, prohibition of the raising of potatoes in

contaminated sections, and utilization of such

sections for the cultivation of crops not damaged by the potato nematode; chemical disinfection of soils in separate and isolated centers

of contamination.

Agricultural institutions have carried out

scientific research in an effort to find resistant

types of potatoes.

United States

(See pp. 3 and 14.)

Yugoslavia

The presence of the pest was recorded in

1964 for the first time in Yugoslavia. The pest

was found in two localities near Kranj in

Slovania, where 12 fields were infested, and

near Fojnica in Bosnia and Hercegovina, where

3 hectares (714 acres) were found infested.

It is supposed that the attacks in BosniaHercegovina were caused by the seed potatoes

used. Six laboratories have been set up for the

analysis of soil samples to determine the presence of the pest in different stages. Legislation

on the control of eelworms is in preparation.
76 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

1948-63

FIGURE 67.—Infested areas in the U.S.S.R.
THE GOLDEN NEMATODE HANDBOOK 77

LITERATURE CITED

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1955. GOLDEN NEMATODE AND OTHER POTATO

DISEASES IN BOLIVIA. U.S. Dept. Agr.

Plant Dis. Rptr. 39(5) :407-408.

(2) BENACHI PHYTOPATHOLOGICAL INSTITUTE.

1964. ANNALS OF THE BENACHI PHYTOPATHOLOGICAL INSTITUTE. 7(1):50-59.

Greece.

(3) BRüCHER, E.

1960-61. (FIRST DISCOVERY OF HETERODERA

ROSTOCHIENSIS WOLL. ON V^^ILD POTATOES (SOLANUM SECT. TUBERARlUM) IN THE ARGENTINE REPUBLIC

AND ITS SIGNIFICANCE AS A PLAGUE

OF THE CULTIVATED SPP.), U. Nac

de Cuyo Facul. de Cien Agr. Rev.

8(1):7-18, illus. (In Spanish.)

(4) CANNON, O, S.

1941. HETERODERA SCHACTII FOUND IN A LONG

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Plant Dis. Rptr. 25(15) :408.

(5)

1941. POTATO NEMATODE DISEASE. NassaU Co.

Farm and Home Bureau News

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(6) CHAMBERLAIN, R., and BARBUXANO, I. V.

1961. POTATO ROOT EELWORM IN THE CANARY

ISLANDS. Nature (London) 189(3):

773.

(7) CHITWOOD, B. G.

1951. THE GOLDEN NEMATODE OF POTATOES.

U.S. Dept. Agr. Cir. 875, 48 pp., illus.

(8) and BUHRER, E. M.

1945. SUMMARY OF SOIL FUMIGANT TESTS MADE

AGAINST THE GOLDEN NEMATODE OF

POTATOES (HETERODERA ROSTOCHIENSIS,

WOLLENWEBER), 1942-44. Helminthol.

Soc. Wash. Proc. 12(2): 40-42, illus.

(9) and BUHRER, E. M.

1946, FURTHER STUDIES ON THE LIFE HISTORY

OP THE GOLDEN NEMATODE OP POTATOES

(HETERODERA ROSTOCHIENSIS WOLLENWEBER) , SEASON 1945. Helminthol.

Soc. Wash. Proc. 13(2) :54-56, illus.

(10) and BUHRER, E. M.

1946. THE LIFE HISTORY OF THE GOLDEN NEMATODE OF POTATOES, HETERODERA

ROSTOCHIENSIS WOLLENWEBER, UNDER

LONG ISLAND, NEW YORK, CONDITIONS.

Phytopathology 36(3): 180-189, illus.

(11) CLEMENT, R. L. and GORDON, F. M.

1942. NEMATODE DISEASES OF POTATOES. Nassau CO. Farm and Home Bur. News

28(10) :2-3.

(12) CLEMENT, R. L. and GORDON, F. M.

1944. PROGRESS REPORT OF THE STATUS OF THE

GOLDEN NEMATODE OF POTATOES IN

NASSAU COUNTY, NEW YORK. Nassau

CO. Farm and Home Bur. News

30(2) :1, 3.

(13) CLEMENT, R. L., MORGAN, R., and TANK, R.

1942. HETERODERA ROSTOCHIENSIS, GOLDEN NEMATODE OF POTATOES IN NEW YORK

STATE. U.S. Dept. Agr. Plant Dis.

Rptr. 26(18):390-391.

(14) and FELDMESSER, J.

1948. GOLDEN NEMATODE POPULATION STUDIES.

Helminthol. Soc. Wash. Proc. 15(2):

43-55, illus.

(15) CHRISTIE, J. R.

1959. PLANT NEMATODES—THEIR BIONOMICS

AND CONTROL. 256 pp., illus. Univ.

Fla., Gainesville.

(16) CoBB, G. S., and TAYLOR, A. L.

1953. HETERODERA LEPTONEPIA, N. SP., A CYSTPORMING NEMATODE FOUND IN SOIL

WITH STORED POTATOES. Helminthol.

Soc. Wash. Proc. 20(1):13-15.

(17) EUROPEAN AND MEDITERRANEAN PLANT PROTECTION ORGANIZATION.

1955. REPORT OF THE INTERNATIONAL CONFERENCE ON POTATO ROOT EELWORM.

EPPO Rpt. (1965), 19 pp., illus.

(18) FENWICK, D. W. and FRANKLIN, M. T.

1951. FURTHER STUDIES ON THE IDENTIFICATION

OF HETERODERA SPECIES BY LARVAL

LENGTH. ESTIMATION OF THE LENGTH

PARAMETERS FOR EIGHT SPECIES AND

VARIETIES. Jour. Helminthol. 25 (1-2) :

57-76.

(19) GRAINGER, J.

1964. FACTORS AFFECTING THE CONTROL OF EELWORM DISEASES. Nematologica 10

(1964) :5-20. Netherlands.

(20) HOLTON, C. S., FISCHER, G. W., FULTON, R. W.,

and others, eds.

1959. PLANT PATHOLOGY PROBLEMS AND PROGRESS, 190 8-195 8. 588 pp., illus. Univ.

Wis., Madison.

(21) ICHINOHE, M.

1952. ON THE SOYBEAM NEMATODE, HETERODERA

GLYCINES N. SP., FROM JAPAN. OYODOBUTSUGAKU-ZASSHI (Magazine of Applied Zoology) 17(1-2):

1-4.

(22) JONES, F. G. W.

1950. A NEW SPECIES OF ROOT EELWORM ATTACKING CARROTS, RE. HETERODERA CAROTAE

N. SP. (MORPHOLOGY). Nature 165

(4185) : 81.

(23) KiRJANOVA, E. S.

1954. SUMMARIES AND PERSPECTIVES IN THE

DEVELOPMENT OF PHYTONEMATOLOGY

IN USSR. Akad. Nauk SSSR. Zool.

Inst. Trudy prob. i. Tematicheskikh

Soveshchanii 3: 9-47.

(24) LiNDHARDT, K.

1959. KARTOFFELAL. Statens Plantetilysyn. 52

pp., illus. Kobenhavn.

(25) LowNSBERY, B. F., and LOWNSBERY, J. W.

1954. HETERODERA TABACUM, NEW SPECIES, A

PARASITE OF SOLANACEOUS PLANTS IN

CONNECTICUT. Helminthol. Soc. Wash.

Proc. 21(1): 42-47.

(26) MACARA, A. M.

1963. CONTRIBUCIAO PARA 0 ESTUDO MORFOLÓGICO E BIOLÓGICO DOS NEMATODOSHETERODERA GOTTINGIANA LIEBSCHER,

1892 E H. ROSTOCHIENSIS WOLLENWEBER, 192 8—^ENCONTRADOS EM PORTUGAL. Broteria. Serie Trimestral

Cicencias Naturais 32: 25-119.

(27) MAI, W. F., and HARRISON, M. B.

1959. THE GOLDEN NEMATODE. N.Y. State Col.

Agr. (Cornell) Ext. Bui. 870, 31 pp.,

illus.

(28) and SPEARS, J. F,

1954. THE GOLDEN NEMATODE IN THE UNITED

STATES. Amer. Potato Jour. 31(12):

387-396, illus.
78 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

(29) MILLER, L. L, HARRISON, M. B., and SCHINDLER,

A. F.

1962. HORSENETTLE AND OSBORNE'S CYST NEMATODES—TWO UNDESCRIBED NEMATODES

OCCURRING IN VIRGINIA. Phytopathology 52(8) :743. (Abstr.)

(30) OOSTENBRINK, M.

1950. HET AÁRDAPPELAALTJE (HETERODERA ROSTOCHIENSIS WOLLENWEBER) EEN GEVAARLIJKE PARASIET VOOR DE EENZIJDIGE AARDAPPEL-CULTUUR. VersL en

Med. Plant. Dienst (Netherlands)

115, 230 pp.

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(32)

(33)

(34)

(35)

(36)

(37)

(38)

(39)

1951. HET ERWTENCYSTENAALTJE, HETERODERA

GOTTINGIANA LIEBSCHER, IN NEDERLAND. Tijdschr. Plantenziekten 57:

52-64.

PETERSON, L. C, and PLAISTED, R. I.

1966. PECONIC, A NEW POTATO VARIETY RESISTANT TO THE GOLDEN NEMATODE. Amer.

Potato Jour. 43(12): 450-452.

POPHAM, W. L.

1949. THE GOLDEN NEMATODE INVADES NEW

YORK. Smithsonian Institution Rpt.

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SASSER, J. N., and JENKINS, W. R., eds.

1960. NEMATOLOGY. 480 pp., illus. Chapel

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SCHMIDT, A.

1871. ÜBER DEN RUBEN NEMATODEN. Zietschr.

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Zollverein 21: 1-19.

SEGURA, C. BAZAN DE.

1952. THE GOLDEN NEMATODE IN PERU. U.S.

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253.

SMALL, T., DUNN, E., and THOMAS, G. E.

1950. POTATO ROOT EELWORM IN JERSEY. Agriculture 52(5) : 212-215, illus. London.

SouTHEY, J. F., ed.

1965. PLANT NEMATOLOGY. (Gr. Brit.) Min.

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SPEARS, J. F,

1953. CHEMICAL CONTROL OF GOLDEN NEMATODE

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(49)

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1962.

1954. THE GOLDEN NEMATODE OF POTATOES AND

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U.S. Dept. Agr. Leaflet 361, 4 pp., illus.

FUMIGATION MEASURES ARE UNDERWAY TO

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Agr. Chem. 17(8): 12-14, 74, illus.

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THE GOLDEN NEMATODE HANDBOOK

APPENDIX I—WORLD POTATO PRODUCTION

79

TABLE 5.—Acreage and production of potatoes in specified countries,

average 1960-6^ or latest available data

Continent and country- Acreage Production

North America:

Canada

Cuba

Mexico

United States

Total ______

Europe :

Austria

Belgium-Luxembourg _ Denmark .

Finland _

France

Germany, West

Greece

Iceland

Ireland

Isle of Man _

Italy

Jersey __

Malta

Netherlands .

Norway _

Portugal

Spain

Sweden

Switzerland

United Kingdom

Total Western Europe

Czechoslovakia

Germany, East

Poland .

Yugoslavia

Bulgaria, Rumania, and Hungary

Total Europe

U.S.S.R.

Asia:

Burma

China :

Cyprus

India _

Israel

Japan

Jordan

Korea,

Korea

Lebanon

Mongolia

Pakistan

Philippines

Syria

Turkey

Total

Taiwan

North _.

Republic

,000 acres

295

20

121

1,882

1,818

415

182

171

190

2,086

2,351

110

3

209

3

927

5

8

330

129

254

992

249

115

763

9,492

1,278

1,821

7,062

751

1,438

21,842

21,600

40

5

23

1,013

13

527

5

363

118

20

5

175

5

13

363

2,688

Million cwt.

46.0

2.5

7.7

265.8

332.0

76.5

41.2

31.6

25.5

312.4

518.4

11.5

.2

42.9

.3

86.1

1.4

.5

86.5

23.8

23.0

101.8

34.1

31.1

150.5

1,599.3

130.5

274.7

942.9

63.6

113.9

3,124.9

1,602.5

1.1

.4

2.9

56.3

2.4

81.3

.2

14.3

9.4

1.8

.5

10.1

A

1.1

37.5

219.7
80 AGRICULTURE HANDBOOK 353, U.S. DEPARTMENT OF AGRICULTURE

TABLE 5.—Acreage and production of potatoes in specified countries,

average 1960-64 or latest available data—Continued

Continent and country Acreage Production

1,000 acres Million cwt.

South America:

Argentina 453 35.5

Bolivia 283 15.9

Brazil 496 25.4

Chile 1- 212 16.7

Colombia 328 19.5

Ecuador 93 7.2

Paraguay - - 5 .2

Peru 575 27.2

Uruguay 63 2.2

Venezuela . - 36 2.5

Total 2,544 152.3

Africa :

Algeria - 75 5.4

Congo 8 .2

Ethiopia 70 3.0

Kenya 133 4.3

Libya 5 .4

Madagascar _ 40 1.5

Mauritius _ 3 .1

Morocco 63 5.0

Mozambique _ _ _. _ 5 .2

Ruanda-Urundi 43 2.2

South Africa 128 9.0

Tunisia 13

58

1.7

United Arab Republic 8.3

Total 644 41.3

Oceania :

Australia 103 12.6

New Zealand 30 5.5

Total 133 18.1

Grand total 51,269 5,490.8

APPENDIX II—INTENSITY OF INFESTATION

The code numbers for various levels of infestation intensity, as laid dov^n at the EPPO

International Conference on Potato Eoot Eelworm at Wageningen, Netherlands, 1955, are

as follows:

CODE No.

I No observation. (This means that no investigation has been made.)

II Free from infestation, as ascertained by—

a. Standard sampling and laboratory

analysis ;

b. Root examination;

c. Appearance of crop. (In this case, however, the report has little value, for

soil may be infested for several years

before disease symptoms appear in the

crop, and other factors, even other

nematodes, may cause the same symp^

toms above ground.)

III Slight infestation, that is, 1-2 cysts per

200 cc. of soil in sampling, but no weak

spots or other field symptoms.

IV Moderate infestation, that is, several

(more than 2 but less than 50) cysts per

200 cc, serious loss of crop, or both.

V Heavy infestation, that is, many (more

than 50) cysts per 200 cc, serious loss of

crop, or both.
THE GOLDEN NEMATODE HANDBOOK 81

APPENDIX III—SOIL SAMPLING FOR POTATO ROOT EELWORM

To sample soil efficiently for potato root eelworm, you need an accurate sampling technique. It is essential to take representative

samples, to process the samples so that the

cysts therein can be found, to avoid mixing

up the samples, and to have sufficient staff

available to handle a satisfactory number of

samples.

The accuracy of the method depends on a

number of factors, including the number of

eelworms present in the field, their distribution, the number of points sampled in the

field, and the subsequent laboratory handling

of the composite field sample. Rather different

methods of soil sampling are used in the

Netherlands and the United Kingdom, but they

appear to result in similar accuracy. In both

countries field sampling is carried to a stage

v^here a marked increase in accuracy could

not be achieved even by a very large increase

in the intensity of sampling.

The most accurate methods are needed in

connection with export and certain certification schemes. Less intensive methods are frequently suitable for purely advisory purposes.

The United Kingdom Method

The United Kingdom method consists in

making a number of soil borings 6 to 8 inches

(15 to 20 cm.) deep with an auger 1.5 in.

(37 mm.) in diameter, or other similar tool,

at random over the area being sampled. For

plants for export purposes 25 such borings

are taken from areas up to 1/2 acre (^/s ha.),

50 from areas of from V2 to 2 acres (^/s to ^/^

ha.) and 5 extra borings for each additional

acre (2/5 ha.). Additional samples are taken

from places where plants to be exported are

growing, from glasshouses, loam heaps, and

any ground under suspicion. The borings are

bulked and taken to the laboratory where the

soil is air dried and thoroughly mixed. Two

subsamples of 250 g. are taken and their cyst

content estimated by a flotation technique.

The Dutch Method

In the Dutch method, a special tool is used

for routine sampling. The tool is designed so

that 50 prods with it will extract approximately 250 cc. of moist soil, which will make

about 200 cc. of dried soil. The usual rate of

sampling is 50 prods per hectare, but for special purposes this is increased to 50 prods per

Ms hectare (about 0.8 acre). The whole sample

is air dried and examined in the laboratory

by flotation. Special attention is given to the

entrances to fields and clamp sites.

Comparison of the Two Methods

The methods differ in the much larger

quantity of soil taken from each field in the

United Kingdom, in the depth sampled, and in

the amount of handling required in the laboratory. As they appear to be comparable in

accuracy, there is no technical reason for preferring one to the other, and the Dutch method

is simpler.

It is therefore recommended that for survey

work a sample should represent not more than

one hectare; that it should consist of at least

50 borings or prods; and that at least 200 cc.

of air-dried soil should be examined. Under

certain circumstances, it is desirable to decrease the maximum acreage covered by the

sample. For example, exporting nurseries and

areas under suspicion should be sampled 3 to

10 times as intensively as other areas.

Details of equipment and technique should

be left to the country concerned, provided that

the results are comparable with those obtained

with the techniques mentioned above.

^ U.S. GOVERNMENT PRINTING OFFICE: 1968—297-095