@,* United States

Department of

Agriculture

0

uIs

Forest 

Southern Forest

Service Research Note

SO-361

Experiment Statlon May 1990

Status and Trends in Gypsy Moth Defoliation

Hazard in Tennessee

Dennis M. May and Bruce W. Kauffman

SUMMARY

The gypsy moth, Lymantria dispar (L.), a major

defoliator of eastern hardwood forests, has become

established in Virginia and is moving towards Tennessee. In preparation for its inevitable arrival,

Tennessee’s timberlands are hazard rated to identify

those areas most susceptible to gypsy moth defoliation. Tree, stand, and site characteristics associated

with gypsy moth defoliation are used to identify USDA

Forest Service, Southern Forest Inventory and

Analysis, survey plots with a high hazard to gypsy

moth defoliation. One-quarter of the State’s timberland, containing 30 percent of the State’s hardwood

inventory, is classified as high hazard. These highhazard acres are unevenly distributed across the

State and can change over time. Hazard rating

provides useful information in planning gypsy moth

detection, monitoring, and prevention activities.

been trapped in the State, and isolated gypsy moth

infestations have been found in neighboring portions

of North Carolina and Virginia. In light of these facts,

it would be prudent to identify those areas of

Tennessee’s forests not susceptible to gypsy moth

defoliation. This can be accomplished by hazard

rating.

Hazard rating attempts to identify those combinations of tree, stand, and site conditions that favor the

gypsy moth and discourage its natural enemies (Hicks

and others 1987, Mason 1987). Hazard rating models

have been developed for forests in the northeast that

have been repeatedly defoliated and those that have

not yet been defoliated (Gansner and others 1987,

Herrick and Gansner 1966, Houston and Valentine

1985, Mason 1987). Although these models cannot be

directly applied to Tennessee’s forests, they were

used to identify general tree, stand, and site conditions associated with gypsy moth defoliation.

Keywords: Survey plot, susceptibility, timberland.

METHODS

INTRODUCTION

The gypsy moth, Lymanfriadispaf (L.), is a major

pest of eastern hardwood forests. Defoliation by this

moth causes tree mortality, tree growth reductions,

and species composition changes that affect the timber, wildlife, recreation, and aesthetic values of

forests. Since its introduction into this country in 1669,

the gypsy moth has been spreading southward from

the northeast. Currently, the gypsy moth is infesting

the northern and eastern portions of Virginia. This

continuing spread is threatening the vast oak-hickory

and Appalachian hardwood forests of the Central and

Southern States.

Gypsy moth defoliation is usually associated with

stands consisting of larger trees, containing a large

component of preferred host trees, and growing on

poorer sites such as ridgetops. Trees growing under

these conditions provide an abundance of food and

protective niches that favor the survival and development of the gypsy moth. Conversely, the lack of understory vegetation and low litter accumulation commonly

associated with these conditions discourage the

gypsy moth’s natural enemies, These general conditions formed the basis for hazard rating Tennessee’s

forests to gypsy moth defoliation because a specific

hazard rating model was not available.

Tennessee’s hardwood forests are directly in the Specific screening criteria were developed to idenpath of this oncoming threat. Male gypsy moths have tify those USDAForest Service, Southern Forest InvenSouthern Forest Experiment StatiorvT-10210 U.S. Postal Servlces Bldg.. 701 Loyola Avenue, New Orleans, La. 70113

Forest Service. U.S. Department of Agriculture.

Serving Alabama. Arkansas. LouIslana. Misslsslppl, E. Oklahoma, Tennessee, E. Texas, Fuerto Rico. U.S. Virgin Islands

1
Dennis M. May is research forester, U.S. Department

Bruce W. Kauffman is forest pest specialist, Tenness

of Agriculture, Forest Service, Southern Forest Experiment Station, Starkville, MS

)ee Department of Agriculture, Division of Plant Industries, Nashville, TN 37219.

tory and Analysis (SOFIA), survey plots having a high

hazard to gypsy moth defoliation. Only plots meeting

the following criteria were considered to be of high

hazard: .

1. Those with the plurality of stocking in oak trees,

one of the most preferred food trees of the gypsy moth

(Gansner and Herrick 1985, Mosher 1915).

2. Those on poor sites with an annual growth

potential of less than 85 cubic feet per acre.

3. Those on upland or pine sites.

4. Those with stands of pole or sawtimber size.

High-hazard plots were further screened to account for the dispersal mechanisms of the gypsy

moth. The female gypsy moth is flightless. This,

together with suppression and eradication efforts, has

slowed the spread of the gypsy moth. However, gypsy

moths have unknowingly been spread long distances

by vehicles and cargoes moving from infested to noninfested areas of the country. This hitchhiker dispersal

mechanism increases the hazard of forests located

near roads.

The main means of natural dispersal is when young

larvae, after climbing onto vegetation and spinning

down on silken threads, are blown by the wind to new

areas. Mason and McManus (1981) have shown that

in nonmountainous terrain, 99 percent of wind-dispersed larvae travel no further than 1 kilometer of

where they hatched. Therefore, to account for the

gypsy moth’s two main means of dispersal, highhazard plots were further screened to identify those

within 3,300 feet of a road.

Tennessee’s forests were hazard rated to gypsy

moth defoliation for two points in time using 1980 and

1989 SOFIA data. In using SOFIA plot data in hazard

rating, it must be emphasized that the plots are part of

a low-intensity sample designed to provide State-level

estimates of forest resource conditions. The plots are

spaced across the State on a 3- by 3-mile grid, and

each forested plot represents approximately 5,760

acres of timberland. These plots cannot be used to

identify individual high-hazard stands, but can be

used to assess the relative hazard of large areas of

timberland, such as whole counties, SOFIA survey

units, or States (fig.1 ).

RESULTS

Today, over 90 percent of Tennessee’s timberland

supports hardwood or mixed (hardwood/softwood)

forests, and hardwood tree species comprise over 80

percent of its inventory volume. Clearly, the State has

a lot at stake should the gypsy moth become established. Based on 1989 SOFIA survey data, one-quarter

of the State’s timberland is classified as having a high

.

39759;

2
Table 1 .dree of timberlend and volume d hardwood classified as susceptible to gypsy moth, Lymsntria dispar (L.), deiolietion, Tennessee,

,989

west CarrOll

Chester

Crockett

Dver

Fayette

Gibson

Hardernan

Heywood

Henderson

Henry

Lake

Lauderdale

Madison

McNairy

Obicn

Shelby

Tipton

Weakley

Unit tota,

West-central senton

Decatur

Hardin

Hickman

Houston

Humphreys

LaWrWlCe

Lewis

Perry

SlBwBfi

Wayne

Unit tota,

C‘Nlt1al Bedford

Can”O”

Cheatham

Clay

Cdfee

Davidson

De Kelb

Dickson

Giles

Jackson

Lincoln

Macon

Marshall

Meury

Montgomery

Moore

Roberts,n

Ruthertord

Smith

Sumner

Trcusdale

Williamron

Wilson

Unit tota,

Susceptible timberland

Within

Total 3,300 feet

tlmberland 1980 1989 of a road

..-.- .._..-.-... Thousandacres .-._ -_----__-

189.1 48.9 48.8 48.8

99.4 24.4 14.9 14.9

15.1 17.8 7.8 7.8

40.4 0.0 10.1 10.1

152.0 19.3 21.7 21.7

38.4 l 18.2 0.0 0.0

247.1 81.9 74.1 88.0

71.2 0.0 0.0 0.0

158.4 19.0 11.3 11.3

178.1 45.0 45.8 45.8

18.0 0.0 0.0 0.0

88.8 0.0 0.0 0.0

140.7 48.9 38.7 38.7

224.4 45.8 57.5 57.5

87.8 0.0 0.0 0.0

111.8 0.0 0.0 0.0

50.9 18.7 0.0 0.0

95.9 0.0 7.4 7.4

1.983.1 382.7 333.5 327.4

172.7 88.8 78.8 70.4

134.8 40.3 43.1 43.1

219.9 25.8 43.0 38.2

297.2 124.2 151.4 145.8

94.2 31 .a 29.0 29.0

241.2 105.3 108.8 108.8

199.8 82.7 75.3 75.8

158.0 75.3 70.2 70.2

223.8 108.0 128.1 108.9

219.7 108.2 100.4 69.0

Growingstock volume Board-fool volume

Total Susceptible

hardwood hardwood

---MiNion cubic lee&---

233.7 57.7

73.4 18.4

33.0 23.5

51.5 18.1

180.9 27.5

47.0 0.0

239.1 91.9

122.5 0.0

175.0 19.0

228.2 79.1

33.2 0.0

114.2 0.0

201.1 59.2

154.7 59.0

128.5 0.0

187.4 0.0

78.8 0.0

118.9 4.7

2.398.9 454.1

tat.4 85.0

181.8 83.0

192.4 38.1

332.0 180.8

113.4 48.6

288.8 133.7

173.3 90.5

183.2 101.5

240.5 157.2

230.1 132.2

TO181 Susceptible

hardwood hardwood

--hf//i;on board leet721.8 144.5

180.3 28.8

165.2 128.9

225.9 71.2

593.2 110.9

155.9 0.0

748.5 288.2

438.5 0.0

541.5 83.4

828.6 258.1

148.5 0.0

51*:1 0.0

709.4 184.7

377.8 140.8

545.9 0.0

871 .o 0.0

280.7 0.0

448.3 18.5

8.345.1 1.433.8

431 .I 239.4

571.9 220.4

520.8 40.8

887.3 497.8

357.8 148.9

770.9 351.7

480.9 239.9

425.8 251.2

815.3 417.4

748.5 487.1

372.6 149.5 138.9 139.0 311.0 154.8 759.7 388.2

2.333.7 895.7 983.3 898.0 2.387.9 1.181.0 8.549.4 3,282.a

74.8 0.0 0.0 0.0 48.4 0.0 138.8 0.0

88.5 8.0 10.4 to.4 83.1 13.5 234.4 48.7

118.2 47.1 47.3 47.3 140.5 71 .o 428.1 207.9

105.1 37.3 18.2 18.2 85.2 18.1 204.2 48.8

114.2 22.4 25.9 25.9 154.3 27.5 486.8 87.1

108.1 20.1 28.4 19.1 110.0 31.8 374.5 112.2

114.2 8.1 11.4 11.4 153.2 l8.8 501 .a 52.8

174.3 79.8 72.1 72.1 215.8 102.1 738.3 375.8

171.8 12.7 19.8 19.8 148.3 29.8 334.1 82.7

135.9 5.1 5.2 a.2 158.4 9.i 564.1 30.4

138.7 5.0 5.9 5.9 104.4 7.0 271.4 18.3

77.0 0.0 0.0 0.0 104.9 0.0 378.0 0.0

89.8 4.2 5.0 8.0 45.7 3.2 148.8 2.8

133.0 1 a.5 13.3 13.3 107.8 23.2 241.8 83.9

138.9 28.2 24.9 24.9 134.8 34.0 385.8 97.4

38.8 8.0 10.5 to.5 52.8 26.0 185.5 104.4

53.0 a.4 0.0 0.0 85.9 0.0 280.7 0.0

155.7 8.5 0.0 0.0 40.8 0.0 89.0 0.0

81.0 8.9 8.8 8.8 74.9 8.5 201.4 17.4

88.2 0.0 0.0 0.0 75.8 0.0 271.1 0.0

30.0 0.0 0.0 0.0 20.8 0.0 49.3 0.0

142.0 13.5 15.8 15.8 149.1 23.9 521.9 90.0

97.0 15.2 to.2 to.2 38.7 11.4 78.9 32.9

2.481.8 349.0 325.9 319.8 2.304.8 454.5 7.079.9 1.449.3

3
Susceptible timberland Growing-stock volume Board-foot volume

Wiihin

SOFIA* Total 3,300 feet Total Susceptible Total Susceptible

survey unit COUn*l timberland 1080 1969 of a road hardwood hardwood hardwood hardwood

_----_._..-.. --,,,ousandac,es. -MiNion cubic fee&-- ---Million board feetPlf4%%l Sledsoe 186.3 68.3 93.1 87.3 (17.6 97.3 277.2 236.2

Campbell 250.2 36.1 52.4 52.4 297.6 68.9 1,143.6 254.2

Cumberland 320.3 141.3 151.4 130.6 295.2 167.2 839.1 467.2

Fentre88 244.1 61.6 69.7 46.7 235.1 75.6 654.5 203.9

Franklin 183.0 74.2 45.6 45.6 171.4 60.3 566.2 225.3

Grundy 165.9 63.0 51 s 51.5 162.5 45.7 446.1 62.9

Marion 251.7 100.4 125.9 ) 80.9 224.3 124.3 695.5 376.5

Morgan 276.2 76.4 101.5 64.5 279.2 103.5 972.5 353.6

overton 170.4 40.6 40.9 40.9 259.9 73.2 927.5 250.6

Picken 68.4 7.3 6.6 6.8 65.9 5.5 271.9 15.6

Putnam 152.3 18.7 10.9 10.9 183.9 a.5 633.8 23.5

SCOtt 300.3 105.6 96.3 71 .o 383.1 142.9 1.168.6 412.7

Sequatchie 137.3 33.4 40.0 40.0 80.3 26.3 211.7 61 .e

“an Buren 135.4 15.5 21.7 21.7 107.5 20.8 343.2 48.8

WS%W3” 93.6 Il.8 to.4 10.4 111.6 7.9 370.5 10.0

White 129.4 15.7 16.9 16.9 172.3 25.2 631.6 66.2

unit total 3.064.8 <.I 669.1 937.2 810.5 3,167.4 1.055.1 10.157.7 3,t10.1

A”dfX.30” 26.1 159.6 56.0 626.6 256.2

Slaunt

Bradley

Carter

Claibome

Cccke

Grainger

Greene

Hamblsn

Hamilton

Hancock

Hawkins

JefferSOtl

Johnson

Knox

Loudon

McMinn

Meigs

Monroe

Polk

Rhea

Roane

Seder

Sullivan

Unicoi

Union

124.0

69.9

92.5

155.5

167.5

163.4

102.6

171.8

32.8

210.7

92.9

177.3

62.2

144.4

127.0

62.3

36.5

82.9

279.0

214.1

126.4

(53.1

127.4

123.6

89.4

102.5

31.1

35.7

16.1

70.3

31.3

42.4

21 .I

31.2

0.0

77.3

7.2

52.4

6.6

51.6

20.5

16.2

17.8

33.1

40.1

46.6

37.6

58.1

35.7

31.9

23.6

35.0

32.6

21.3

0.0

62.6

43.7

49.3

32.4

41 .I

0.0

65.6

5.8

45.6

17.0

53.8

23.8

22.7

11.2

35.5

47.9

40.1

33.0

52.6

47.2

37.6

18.7

21.6

21.3 69.3 30.9 214.4 112.1

0.0 61.7 0.0 234.9 0.0

62.6 235.6 66.4 794.9 286.0

43.7 184.6 56.2 614.2 167.1

49.3 190.4 62.1 618.2 189.7

27.0 138.0 36.0 468.5 118.4

22.6 205.2 62.2 727.4 205.3

0.0 49.2 0.0 198.2 0.0

65.8 156.6 77.4 526.9 300.1

5.6 61.6 3.4 202.2 6.1

45.8 164.1 45.2 531.4 104.6

17.0 62.7 44.6 317.0 185.4

40.3 162.9 60.0 469.1 149.1

23.6 129.9 35.6 516.1 136.0

22.7 54.2 35.1 223.8 137.7

11.2 107.1 10.8 362.6 29.3

35.5 71.1 39.7 201.4 113.9

44.3 275.9 66.5 844.3 180.6

40.1 128.2 37.9 426.5 121.6

33.0 136.0 48.2 401.5 122.4

52.6 162.7 73.0 536.3 172.3

47.2 114.4 44.6 376.5 160.7

37.8 126.8 47.3 366.6 135.5

18.7 123.7 26.0 396.0 90.0

21.6 100.0 26.9 356.6 111.6

Washington 50.3 25.9 22.5 18.3 76.1 34.5 266.0 126.3

Unit total 3.442.0 696.7 886.0 634.5 3.54.6.2 1.152.7 11,866.i 3.730.2

state total 13.265.2 3,395.2 3445.9 3.190.0 13.787.0 4,297.4 43,908.2 13.005.8

*SOFIA=Scuthern Forest Inventory and Analysis.
Percent

018 filizzl 1 TO 2s I25 TD 58 ->5M

Figure 2.- Percentage of timberland with high hazard to gypsy moth, Lymantria dispar (L.), defoliation, Tennessee, 7989.

Percent

OrB cz?ZJl TO25 0 25 TO 5M )5M

Figure 3.- Percentage of hardwood growing-stock volume with high hazard to gypsy moth,

Lymantria dispar (L), defoliation, Tennessee,

7 989.

Percent

018 iYZZ31 TO 25 I25 TD 5E1 >5M

Figure 4.- Percentage of hardwood board-foot volume with high hazard to gypsy moth, Lymantria dispar (L), defoliation, Tennessee, 1989.

5
Percent

-10 ,

l7izzzl1lu75 0 75 TU 33

Figure 5.- Percentage of area with high hazard to gypsy moth, Lymantria dispar (L), defoliation within 3,300 feet ofa road, Tennessee, l@SQ.

I 1 I J

DECRFASE No CHANGE INCRWSE

Figure G.-Change in area with high hazard to gypsy moth, Lymantria dispar (L), defoliation, Tennessee, 1980-89.

hazard to gypsy moth defoliation (table 1). These

acres are the most likely to be defoliated should the

gypsy moth become established in the State. Thirty

percent of the State’s hardwood inventory volume is

found on these high-hazard acres (table 1). Neither

the high-hazard acres nor inventory volumes are evenly distributed across the State, but they are concentrated in SOFIA survey units and counties where

forest conditions are similar to those associated with

gypsy moth defoliation (figs. 2, 3,4). This is especially

true of the counties in the west-central SOFIA survey

unit, where over 40 percent of the timberland and half

of the hardwood inventory volume are classified as

high hazard (table 1).

Over the entire State, 93 percent of the high-hazard

acres fall within 3,300 feet of a road, making them even

more susceptible to gypsy moth defoliation. These

acres are concentrated in the more developed areas

of the State and have their lowest proportions in the

more remote sections of the west-central and plateau

SOFIA survey units and mountain counties of the eastern SOFIA survey unit (fig. 5).

Since the 1980 survey, the number of high-hazard

acres in the State has increased by less than 2 percent. However, the State total masks the fact that all of

the increase was found in the west-central and plateau

SOFIA survey units (table 1). Changes in gypsy moth

hazard are more evident at the county level (fig. 6)

where normal stand development and wood harvesting practices have combined to shift species composition and stand size structure, resulting in some

dramatic shifts in gypsy moth defoliation hazard over

time (table 1). Even though individual county hazards

have changed since 1980, high-hazard acres in 1989

are still generally concentrated in the same areas as

in 1980.

Although the number of high-hazard acres in the

State has increased only slightly since 1980,

hardwood inventory volumes on these acres have

increased substantially, increasing by 16 percent for

6
growing-stock and 23 percent for sawtimber. These

increases are in line with the general maturation of

Tennessee’s timberlands since 1980. Despite these

increases, the proportion of susceptible inventory

volume to total inventory volume in the State has

remained essentially the same over time.

CONCLUSIONS

Hazard rating Tennessee’s timberlands using

SOFIA survey data provides a useful tool in preparing

for the gypsy moth’s inevitable arrival. Hazard rating

provides an assessment of the quantity and extent of

the forest resource susceptible to the gypsy moth. It

also identifies areas of the State where gypsy moth

detection and evaluation activities as well as possible

gypsy moth preventative actions should be concentrated for maximum effectiveness and efficiency.

Hazard rating with data from successive SOFIA surveys reveals that the gypsy moth hazard is dynamic

and changes as forest conditions are influenced by

natural and man-caused factors, The recognition that

gypsy moth hazard can be influenced by both natural

and man-caused factors provides a basis for developing forest practices aimed at preventing gypsy moth

defoliation (Gottschalk 1987). As dynamic as it is,

gypsy moth hazard rating needs to be periodically

updated in order to insure the maximum effectiveness

and efficiency of any gypsy moth planning efforts or

management activities.

DEFINITIONS

Timber/and.-Forest land that is producing, or

capable of producing, crops of industrial wood and

not withdrawn from timber utilization,

Hardwoodgrowing-stockvolume.-The cubic-foot

volume of sound wood from a i-foot stump to a minimum 4.0-inch top diameter, or point where the central

stem breaks into limbs, on live trees of commercial

species that are at least 5 inches in diameter at breast

height, have one 12-foot log or two &foot logs, now or

prospectively, and meet regional specifications for

freedom from defect.

Hardwood sawfimber volume--The board-foot

volume (International t/-inch rule) of sound wood from

a i-foot stump to a minimum 9.0-inch top diameter, or

point where the central stem breaks into limbs, on live

trees of commercial species that are at least 11.0

inches in diameter at breast height, have one 12.foot

log ortwo &foot logs, and meet regional specffications

for freedom from defect.

LITERATURE CITED

Gansner, David A.; Herrick, Owen W. 1985. Host

preference of gypsy moth on a new frontier of infestation. Res. Note NE-330. Broomall, PA: U.S. Depanment of Agriculture, Forest Service, Northeastern

Forest Experiment Station. 3 p.

Gansner, David A.; Herrfck, Owen W.; Mason, Garland

N.; Gottschalk, Kurt, W. 1987. Coping with the gypsy

moth on new frontiers of infestation. Southern Journal of Applied Forestry. 1 i(4): 201-209.

Gottschalk, Kurt W. 1987. Prevention: the silvicultural

alternative. In: Fosbroke. Sandra; Hicks, Ray R., Jr.,

eds. Proceedings of coping with the gypsy moth in

the new frontier; 1987 August 4-6; Morgantown. WV.

Morgantown, WV: West Virginia University Books:

92-l 04.

Herrick, Owen W.; Gansner, David A. 1986. Rating

forest stands for gypsy moth defoliation. Res. Pap.

NE-583. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station. 4 p.

Hicks, RR., Jr.; Caster, J.E.; Mason, G.N. 1987. Forest

insect hazard rating. Journal of Forestry. 85(10): 20-

26.

Houston, David R.; Valentine, Harry T 1985. Classifying forest susceptibility to gypsy moth defoliation.

Agric. Handb. 542. Washington, DC: U.S. Depanment of Agriculture. 19 p.

Mason, C.J.; McManus. M.L. 1981. Larval dispersal of

the gypsy moth. In: Doane, C.C.; McManus, ML..

eds. The gypsy moth: research toward integrated

pest management. Agric. Tech. Bull. 1584.

Washington, DC: U.S. Department of Agriculture.

161-202.

Mason, Garland N. 1987. Rating stand susceptibility to

gypsy moth defoliation. In: Fosbroke, Sandra: Hicks,

Ray R., Jr., eds. Proceedings of coping with the

gypsy moth in the new frontier; 1987 August 4-6;

Morgantown. WV. Morgantown, WV West Virginia

University Books. 6572. _ Masher, F.H. 1915. Food plants of the gypsy moth in

America. Agric. Bull. 250. Washington. DC: U.S.

Department of Agriculture. 39 p.