9!i!ii$ ResearchNo&

1979

Using Bayleton (Triadimefon) to Control Fusiform Rust

in Pine Tree Nurseries

G. A. SNOW, S. J. ROWAN, J. P. JONES,

W. D. KELLEY. AND J. G. MEXAL

BayletorP was field-tested for fusiform rust

control at eight pine tree nurseries during the

spring of 1978. Four to six foliar sprays of this

systemic fungicide were as effective as ferbam

sprayed 16 to 36 times. Seed treatment with Bayleton reduced infection levels but did not significantly improve rust control in plots sprayed with

Bayleton. At high rates, Bayleton sprays inhibited

seedling growth and mycorrhizal development.

However, proper application rates should minimize this problem and result in no loss of seedling

quality.

Additional keywords: Cronartium cpercuum f. sp.

fusiforme, loblolly pine, slash pine, fungicide.

The systemic fungicide Bayleton’ (triadimefon),

(l-[4-Chiorophenoxyl-3, 3-dimethyl-l-1 -[I H-l ,2,

‘Bayleton is a registered trademark of Farbenfabriken Bayer

Gmbli, Leverkusen.

The use of trade, firm or corporation names in this publication is for the information and convenience of the reader. Such

use does not constitute an official endorsement or approval

by the USDA of any product or service to the exclusion of

others that may be suitable.

This publication reports research involving fungicides. All

4-triazol-1 -yl]-2-butanone) is effective against

several plant diseases including rust fungi attacking a wide variety of hosts (Siebert 1976). The

chemical is translocated in plants, and application

methods have included foliar sprays, soil

drenches, and seed treatment to achieve both

protective and curative control (Kaspers 1977).

In recent greenhouse trials, Bayleton showed

considerable promise for control of fusiform rust

on slash (Pinus ellioffii var. elliotfii Engelm.) and

loblolly (Pinus taeda L.) pine seedlings. As a seed

treatment, Bayleton protects pine seedlings at

least until after the plants shed their seed coats

(Mexal and Snow 1978). Foliar sprays have been

effective applied both before and after inoculation

with Cronartium quercum (Berk.) Miyabe ex Shirai

f. sp. fusiforme (Kelley 1979, Snow 1978).

Since fusiform rust is a serious problem in

southern pine tree nurseries (Rowan 1977a) and

more effective controls are needed, we tested

Bayleton at pine tree nurseries in six southern I(

States in 1978. Our purpose was to evaluate Bayuses of fungicides must be registered by appropriate State

and Federal agencies before they can be recommended. Use

fungicides only when needed and handle them with care. If

fungicides are handled, applied, or disposed of improperly they

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

water supplies. Follow the directions and heed all precautions

on the container label.

Southern Forest Experiment Station/T-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mississippi, Eastern Oklahoma, Tennessee, Eastern Texas.
leton under a wide range of environmental conditions, compare seed treatment with foliar sprays,

establish a desirable rate for Bayleton sprays, and

compare the material with ferbam, which has been

commonly used for rust control in pine tree nurseries.

MLTHODS

We adopted a standard test procedure and

followed it with minor variations at all the nurseries. The experimental design was a factorial

of seed soak and spray treatment in a randomized

complete block with three replications. Two seed

treatments (untreated and Bayleton-treated) and

five spray treatments were tested (table 1). A

replication consisted of three adjacent nursery

beds. In portions of these beds the combinations

of seed soak and spraying were assigned at random. The beds were 1.22 m (4 ft) wide and spray

plots were usually 15.25 m (50 ft) long. At the

Ashe and Weyerhaeuser nurseries, the high dosage Bayleton-treated plots and the controls were

reduced to 7.6 m (25 ft) long to avoid possible

heavy losses from rust infection or phytotoxicity.

Plots at the Beauregard nursery were 9.2 m (30

ft) long. The nursery beds were sown with slash

pine seed at all nurseries listed in table 1, except

at the Weyerhaeuser nursery where loblolly seed

was sown. Similar experimental plots were also

established in loblolly pine beds at the Hauss,

Stauffer, and Miller nurseries in Alabama. Data

from these tests are not presented because no

trees were infected with fusiform rust.

Previously stratified seeds were soaked in an

aqueous solution of Bayleton (25 or 50 WP, 800

mg. a.i./liter [.l oz/gal]) at room temperature for

24 hours. Before planting, treated seed were airdried and coated with bird repellent. Sprays were

applied with tractor-driven power sprayers. For

all Bayleton sprays, Agrodex surfactant was used

at the rate of 1.3 ml/liter (1 pt/lOO gal) of water.

The first Bayleton sprays were applied after about

50 percent of the seed germinated and then at

2-week intervals. When long rainy periods occurred during the second week after a spray, the

Bayleton application followed within 2 days after

the rain. This spray date became the base for

a new 2-week schedule. Dates for the last Bayleton sprays varied from the first week in June to

the first week in July in 1978. Ferbam (76 WP)

applications in the test followed the same schedule used for the rest of the nursery, usually 2

or 3 times a week from seed germination until

the first week of July.

After the growing season (November-January),

we lifted seedlings from three or five randomly

selected .3 m x 1.2 m (1 ft x 4 ft) areas within

all 30 plots. These seedlings were examined for

fusiform rust galls, and an equal number of them

from each plot were measured for height growth

and weighed. Mycorrhizal development was assessed from sample seedlings lifted from experimental plots at nurseries in Florida, Georgia, and

Mississippi in late summer of 1978 and in January

1979. Assessments were based on visual estimates of the percentage of feeder roots with

ectomycorrhizae.

RESULTS

Relative to previous years (Rowan 1977b), rust

infection was low at nurseries in Louisiana, Mississippi, and Georgia and was very low at nurseries in Alabama and Florida (table 1). Despite

this low infection rate, fungicide evaluation was

usually possible. At the Ashe, Beauregard, Davisboro, and Weyerhaeuser nurseries, the Bayleton

seed treatment significantly reduced the incidence of fusiform rust. The effect of the seed

treatment was less evident in plots sprayed with

the fungicides; in plots sprayed with Bayleton

differences attributable to seed treatment were

not significant at any nursery.

Bayleton spray treatments gave better control

than ferbam at the Ashe and Weyerhaeuser nurseries and were as effective at all others. The

medium and high dosages of Bayleton appeared

to be more effective than the low dosage spray

in beds planted with untreated seed but differences among the three rates of Bayleton were

not significant. Ferbam sprays alone significantly

reduced rust incidence at the Ashe, Beauregard,

and Davisboro nurseries but not at the Weyerhaeuser nursery. Statistical comparisons were not

made of data from the Buckeye Cellulose, Walker,

and St. Regis nurseries because of the low rust

infection. The reader is invited to observe that

G. A. Snow is Principal Plant Pathologist, Southern Forest Experiment Station, Forest Service-USDA, Gulfport, Mississippi;

S. J. Rowan is Principal Plant Pathologist, Southeastern Forest Experiment Station, Athens, Georgia; J. P. Jones is Assistant

Professor, Department of Plant Pathology and Crop Physiology, Louisiana State University; W. D. Kelley is Professor, Department

of Botany and Plant Pathology, Auburn University; and J. G. Mexal is Regeneration Specialist, Weyerhaeuser Co., Hot Springs,

Arkansas.

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Table 1 .-The effect of fungicidal sprays and seed treatment on fusiform rust incidence at seven pine tree nurseries’

Nursery

W. W. Ashe Nursery

Brooklyn, Miss.

Foliar spray and Number of

rate (a.i.) per hectare? sprays

Control 0

Ferbam 2.2 kg 3 1

Bayleton .26 kg 4

Bayleton .56 kg 4

Bayleton .64 kg 4

Percentage of galled plants

No Bayleton

seed treatment seed treatment

3.5 a 3 .2 c

2.1 b .6 c

.5 c .l c

.o c .l c

.o c .o c

Beauregard Nursery

Beauregard, La.

Davisboro Nursery

Davisboro, Georgia

Weyerhaeuser Nursery

Aliceville, Ala.

Buckeye Cellulose

Perry, Fla.

St. Regis Nursery

Lee, Fla.

Walker Nursery

Reidsville, Ga.

Control

Ferbam 2.6 kg

Bayleton .26 kg

Bayleton 56 kg

Bayleton 1.12 kg

0 2.5 a 1.1 b c

1 2 0.8 bc 0.4 b c

3 1.0 bc 0.3 bc

3 1.2 b 0.4 b c

3 0.6 b c 0.5 b c

Control

Ferbam 2.6 kg

Bayleton .26 kg

Bayleton .56 kg

Bayleton 1.12 kg

0 5.3 a 2.0 b

3 6 0.5 c 0.1 c

5 0.9 b c 0.1 c

5 0.0 c 0.0 c

5 0.0 c 0.0 c

Control

Ferbam 2.2 kg

Bayleton .26 kg

Bayleton .56 kg

Bayleton .64 kg

0 .9 a

1 6 1.3 a

4 .3 b

4 .l b

4 .l b

.5 a b

.5 a b

.2 b

.l b

.O b

Control 0 0.2 0.0’

Ferbam 2.6 kg 3 2 0.0 0.0

Bayleton .26 kg 5 0.0 0.0

Bayleton .56 kg 5 0.0 0.0

Bayleton 1.12 kg 5 0.0 0.0

Control 0 0.3 0.2’

Ferbam 2.6 kg 2 0 0.0 0.0

Bayleton .26 kg 6 0.0 0.0

Bayleton 56 kg 6 0.0 0.0

Bayleton 1.12 kg 6 0.0 0.0

Control 0 0.2 0.2’

Ferbam 2.6 kg 2 5 0.1 0.1

Bayleton .26 kg 5 0.0 0.0

Bayleton .56 kg 5 0.0 0.0

Bayleton 1 .12 kg 5 0.0 0.0

‘Tests were on slash pine at all nurseries except Weyerhaeuser where loblolly pine was used.

ZEnglish equivalent of application rates are: .26 kg/hectare = 4 oz/acre; .56 kg/ha = 6 oz/acre; .64 kg/ha = 12 oz/acre;

1.12 kg/ha = 16 oz/acre; 2.2 kg/ha = 2 lb/acre and 2.6 kg/ha = 2.3 lb/acre.

‘Values for the 10 means ,for each nursery followed by the same letter are not significantly different at the .05 level according

to Duncan’s multiple range test.

‘Infection levels were too low to meet requirements of the Analysis of Variance so statistical comparisons among treatments

are not presented.

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Table P.-The effect of fungicidal sprays on seedling growth and ectomycorrhizal development at six pine tree nurseries’

Foliar sorav and

Average

olant heiaht (mm)

Average percentage of

mvcorrhizae develooment

Nursery

. , “. I

rate (a.i.) per hectare? 6176 l/79 6176 l/79

Beauregard Nursery Control 210.2 a 3 46.0 a

Beauregard, La. Ferbam 2.6 kg 239.5 a 50.5 a

Bayleton .26 kg 206.0 a 47.5 a

Bayleton .56 kg 206.1 a 44.5 a

Bayleton 1 .12 kg 216.2 a 44.0 a

Buckeye Cellulose

Perry, Fla.

Control

Ferbam 2.6 kg

Bayleton .26 kg

Bayleton 56 kg

Bayleton 1 .12 kg

235.0 a 242.4 a 15.6 a 33.2 a

241.5 a 235.1 a 14.4 a b 34.6 a

212.7 a 210.5 b 10.6 c 29.7 a

196.6 b 207.1 b c 11.3 bc 31.2 a

176.9 b 166.5 c 7.1 c 30.0 a

Davisboro Nursery

Davisboro, Ga.

Control 210.6 a

Ferbam 2.6 kg 196.5 ab

Bayleton .26 kg 201.5 a

Bayleton 56 kg 196.2 ab

Bayleton 1 .12 kg 191.5 b

232.1 a 13.3 a 27.7 a

236.6 a 16.6 a 27.5 a

220.3 ab 6.5 c 2; 0 a

212.6 b 4.5 c 27.3 L

205.0 b 11.4 b 31.4 a

St. Regis Nursery

Lee, Fla.

Control

Ferbam 2.6 kg

Bayleton .26 kg

Bayfeton .56 kg

Bayleton 1.12 kg

136.9 a

141.6 a

136.7 a

111.9 b

76.2 c

172.9 ab 15.0 a 43.0 b

162.5 a 16.0 a 46.4 ab

161.5 a 6.3 b 44.5 ab

163.2 b 7.6 b 51.6 a

149.4 c 5.2 b 46.4 ab

Walker Nursery

Reidsville, Ga.

Control

Ferbam 2.6 kg

Bayleton .26 kg

Bayleton 56 kg

Bayleton 1 .12 kg

216.0 a

201.3 a

205.3 a

174.5 b

163.6 b

231.1 a

234.6 a

207.7 b

205.7 b

211.6 b

14.0 ab

20.0 a

16.2 a

11.3 b

11.7 b

49.9 a

49.4 ab

49.6 a

47.2 ab

43.2 b

Weyerhaeuser Nursery Control ..,. 211.5a

Aliceville, Ala. Ferbam 2.2 kg 203.6 a

Bayleton .26 kg 207.3 a

Bayleton .56 kg 203.6 a

Bayleton .64 kg 199.7 a

_----_--._

‘Seed treatments did not affect growth or mycorrhizae and data represent a combination of both seed treatments.

?English equivalent of application rates are: .26 kg/ha = 4 oz/acre; .56 kg/ha = 6 oz/acre; .64 kg/ha = 1 2 oz/acre; 1.12

kg/ha = 16 oz/acre; 2.2 kg/ha = 2 lb/acre and 2.6 kg/ha = 2.3 lb/acre.

%eparately for each nursery and for each response variable the 5 means for each nursery followed by the same letter are

not significantly different at the .05 level according to Duncan’s multiple range test.

the most infection occurred at these nurseries

in control plots and no infected trees were found

in plots sprayed with Bayleton.

Bayleton sprays inhibited seedling growth and

mycorrhizal development at nurseries in Florida

and Georgia (table 2). By January, however, the

differences in mycorrhizal development were no

longer evident at the Beauregard, Davisboro, and

St. Regis nurseries. A similar pattern of mycorrhizal development occurred at the Ashe nursery,

but no differences in growth or color of the trees

were observed that could be related to the spray

treatments at the Ashe, Beauregard, Hauss, Miller,

Stauffer, and Weyerhaeuser nurseries. The lower

phytotoxicity at these six nurseries was probably

due to the fewer sprays and, consequently, lower

dosage applied.

Fresh weight of slash seedlings from beds with

treated seed averaged 1.9 grams less than seedlings from untreated seed beds at the Ashe nursery while at the Weyerhaeuser nursery, loblolly

seedlings grown from treated seed were 3.2

grams heavier than those produced from untreated seed. These differences in seedling size

did not affect number of plantable seedlings at

either nursery and were probably unrelated to

4
treatment. Seedling growth was not affected by

the seed treatment at the other nurseries, Treatments did not affect seedling stand density at any

of the nurseries.

Bayleton promises to be an excellent fungicide

for fusiform rust control in pine tree nurseries.

One might conclude from these tests, particularly

those at the Ashe and Weyerhaeuser nurseries,

that the seed treatment alone would provide adequate control of fusiform rust throughout the 2-

to 3-month infection season. We do not wish to

convey this idea. Weather favorable for pine infection only occurred at the above nurseries during and soon after seed germination. If infection

had occurred later, as was likely the case at the

Beauregard and Davisboro nurseries, additional

benefit would likely have been realized from the

follar sprays. Experiments are currently underway

to determine the length of time that pine seedlings

are protected by Bayleton seed treatment.

Although rate and method of application appear

to be important to avoid reduction in the size of

pine seedlings, Bayleton holds many advantages

over ferbam:

1. When used as a seed treatment, Bayleton

protects during germination while ferbam must

be applied daily to provide equal protection.

2. Fewer sprays are required and this should

reduce tractor pad compaction, manpower requirements, and nursery bed deterioration during

wet weather.

3. Since Bayleton is a systemic fungicide, timing

of sprays is less critical.

Bayleton is not currently available for commercial use in pine tree nurseries. It was recently

registered in the United States for control of Azalea blight, and Mobay Chemical Corporation is

seeking approval from appropriate federal and

state agencies to label the compound for forestry

uses.

LITBRATURE CITCD

Kaspers, H.

1977. Practical importance of the systemic

properties of Triadimefon Provisional results.

In Internal Therapy of Plants, Proc. Int. Symp.

(August 1976) p. 361-364. A. Fuchs, ed. Wageningen, The Netherlands.

Kelley, W. D.

1979. Control of fusiform rust on loblolly pine

seedlings with the systemic fungicide, Bayleton. Phytopathology 69(1):1 -A!51 -A6.

Mexal, J. G., and G. A. Snow.

1978. Seed treatment with systemic fungicides

for the control of fusiform rust in loblolly pine.

U.S. Dept. Agric. For. Serv. Res. Note

SO-238, 4 p. South. For. Exp. Stn., New Orleans, La.

Rowan, S. J.

1977a. Fusiform rust management strategies in

concept: nursery management. In Managemen! of fusiform rust in southern pines,

Symp. Proc. p. 116-121. R. J. Dinus and R.

A. Schmidt, eds. Univ. Fla., Gainesville.

Rowan, S. J.

1977b. Incidence of fusiform rust in Georgia

forest tree nurseries, 1959-I 973. Tree Planters’ Notes 28(2):17-l 8, 29.

Siebert, R.

1976. New approach to the control of rust diseases of cereals with Bayleton. Pflanzenschutz-Nachr. 29:303-309.

Snow, G. A.

1978. Reduction of fusiform rust on slash pine

seedlings with foliar sprays of Bayleton. Phytopath. News 12(9):197.

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