AUGUST 1962

REPORT NO. 62-82

THE 1962 SURVEY OF EIM SPANWORM DEFOLIATION IN THE' SOUTHERN APPALACHIAN MOUNTAJNS

by

w. M. Ciesla and A. T.·nrooz

Introduction Surveys to determine the extent and degree of defoliation by the elm span­ worm, Elmomos subsignarius (H bn.) were conducted during the period June 18 - July 18, 1962. These consisted of an aerial survey made June 18~22, followed by a.-series of ground observations. The aerial survey.was conducted by w. M. Ciesla, Zone l, Pest Control Branch, A. T. Drooz, Southeastern Forest Eiq:,eriment Station, and L. c. Loudermilk, Tusquitee District, Nantahala National Forest. H. L. Lambert, Zone l, Pest Control Branch, and Beecher Colvin, Tellico District, Cherokee National Forest, assisted with the ground observations. The elm spanworm has been epidemic in the southern Appalachians since 1954, when hardwood defoliation wss detected in the vicinity of Potato Patch and Three Forks Mountain in north . Generally speaking, the outbreak has moved in northerly and easterly directions. In recent years it has encompassed over one million acres of hardwood forests in Georgia, Tennessee, and North Carolina. Survey Method

Aerial Surveys: A Cessna 172 was contracted for the aerial survey. Defo­ liation was sketch-mapped from an altitude of approximately 1000 feet above the terrain at an air speed ranging between 90-100 m.p.h. Due to the rugged terrain of the southern Appalachians, contours and rldge tops were flown, rather than pre-determined, straight flight lines. The survey crew consisted of two mappers and a tracker. The tracker kept the mappers oriented as they sketch-mapped the defoliation acccrd:,.ng to the following categories: Light: Light defoliation consisted of areas of complete defoliation of hickory and black walnut, with only shothole or leafedge feeding on oaks and other hardwoods; the d'l!llage on these latter species not being visible from aircraft flown at a safe altitude in this mountainous terrain. Moderate: Complete stripping of hickory and black walnut, plus visible defoliation of oaks and other hardt•oods, was classed as moderate. In this category, green foliage was present in varying degrees on many trees. Heavy: Defoliation was defined as 11 heavyll when continuous areas of com­ pletezy defoliated hardwoods were obi,erved:

Goggles fitted with two photographic filters, Cyan 10 C and Magenta 30 M, were worn by the mappers to aid ..in delitieat:IJ:it' defoliation boundaries. These filters were particularfy helpi'ul Jri picking up additional areas of light defoliation. · · A total of 12 hours and 35 minutes of flying time were required to complete the aerial survey, ·.. , Ground Observations: A series of ground observations were made to supple­ ment the aerial survey, A s~ries of 95 plots established to predict elm spanworm defoliation potential: were used to give detail to the ground check. Individual tree and area wide defoliation were estimated using the same categories described above, A large additional area of very light defolia­ tion, not visible from the air, was detected through the use of.these ground observations. Results There was a slight reduction in total area defoliated over 1961; 1,451,000 acres beilig damaged in 1962 as compared with 1,532,000 acres.the previous year. This is the second successive year such a reduction has occurred (Table l), .

Elm spanworm defoliation in the southern Table l -- ApPalachian Mountains, 1954-1962 Year Class of Defoliation Light Moderate Heav:, Total ---Thousands of Acres--- 1954 Undetermined 1955 1.5 1.5 1956 10 39,5 l.5 51 1957 200 81 19 300 J.958 425 114 31 570 1959 724 136 860 l96o 1,488 183 1,611 1961 1,073 272 187 1,532 1962 l,209 242 1,451

-2- Tabl~r; de!oliati~n ij the southern . ·· '.6i sQes Mii !W, 811d 1962 r.· Total \r-l Defoliation: GeorgiU. Ttmn.'11J!!et: N. Q~i s. c.:' ---Thousands o! Aores-•• 1961 Y Light 513 66 434 0 1,073 '.') '' . ~ ty··~·-·-····· Moder&tE! 114 30 128 272 .-~·-····. Heavy 6 25: 156 0 187 . TOTAL 693 121 -~ 718 0 l:,532

Light 509 46 632 22 1,209 Moderate-He&!?: 52 17 173 0 242 TOI'AL 561 63 805 22 l,451

The area o! moderate and heavy defoliation was al.so reduced considerably. No extensive areas of heavy defoliation were found. Some 242,000 acres of moderate-heavy -defoliation occurred, compared with 272,000 acres of moderate and 187,000 acres of heavy which occurred in 1961 (Table 2).

The ehn spanworm continued its northward and eastward spread in 1962. i ( \ ; Defoliation vas observed !Qr the first tillle in the Great Smoky Mountains National . P$l'k. . Damage was also noted in South Carolina for the first tillle. Moderate defoliation occurred on ttie eastern slopes of the Nantahala Mountains ~ tl:lroughout the eastern hall' of Grlµlalll County in Noi·th C&rolina. · In Georgia, s.cattered patches of moderate damage occurred along the Blue Ridge Divide and in piµ-ts of Rabun County (Figure 1).

Unlike previous years, when the heaviest damage occurred on ridgetops, in 1962 heaviest defoliation cOIIDllonly was found on spur ridges. This was ' [ part:j.cularl:y true in .North Carolina where the nighest elevations within the.. infestation occur. Detailed descriptions of elm spanworm defoliation are given below by state and county: Georgia

Fannin Qount{h Light defoliation was p~esent in. the southeast quarter of the county, e northernmost limit being Duncan Ridge. Gilmer Coun!{: Ligl;lt defoliatior. was observed along the eastern edge of the county th Riley Mountain being the northern limit and Frosty Moun­ tain the southern limit, .

Y DFoo!, A. T., Solofuon, J. D., and Lambert, H. L. 1961, the 196! survey of elm spanworm defoliation in the southern Appalachian Mountains, U.S.D.A., Forest Se::."Vice, Division of State and Private Forestry, Atlanta, Georgi~, Forest Insect Slll'Vey Report 61-2. -3- - . ------

Union Co,%: An area bounded Oil. ihlf~(\Ql'th ~ Duncan Ridge, the Blue· · Ridge Div on the south "and Woli'pen .Rddge on :ttie·-east; was lightly defoliated. A small area of light ·,Tray Mountain. . -. . Towns County: Light defoliation occurred south and east of the Chatuge Reservoir. ~oderate defoliation was detected from Blue Ridge Gap south to YOUl'lgs Lick. ' . . . . .

Rabun County: Light damage occurred over· most of' Rabun Count:, with the excepUon 0£ the extreme northeast portion; east of Bent Ridge and Willis Knob. Moderate damage occurred in patches on r_idge tops_ surrounding l,ake Burton; along the Blue Ridge Divide from Blue Ridge Gap· to Cedar c;w:r · Knob and Youngs Lick; also from Chestnut Knob; south along· Grassy Ridge and Elisha Mountain to Taylor Gap and Turkey Mountain.. · A large area of IIICderate damage occurred northeast of Clayton frolll Ford Mountam·wst to Sheepclif'f' and Chestnut Mountains and south to and P:!nnacle Knoll. Additional patches of moderate defoliation occurred from Tiger Mountain to Glassy Mountain and along the Habersham County line in the vicinity of Oakey Mountain.

Habersham County: The southern boundary of' light defoliation exiended from .take Yonah to Tllrnerville and west· to Yellow Mountain. Small · patches of' moderate damage occurred on Grassy Mountain,· along the Rabun County line and the Blue Ridge Divide.

Tennessee Monroe County: With the exception of a rrJ.nor amount of light damage n.ear Deais Gap in Blount County, all defoliation due to the elm spanworm in Tennessee occurred in Monroe County, The southem limit of' lig:'lt .dei'olia- . tion was Gravelstand Top and sycamore Creek; the western limit was Miller Ridge; and the northern boundary was the Little Tennessee Riv1a>r. Moderate damage occurred along Saltespring Mountain and Cowcamp Ridge and from .. Turkey.Creek Mountain and Flat Mountain north to Stiffknee Knob and east to the North Carolina line. Heavy damage occurred 1.-:i scattered spots on Pine Ridge and Brush Mountain.

-1'- :.,, North Carolina r-, Cherokee County: Light defoliation occurred east of Chestnut Mountain, Unaka, Hiawassee Reservoir, Panther Top Mountain, and Sheep Knob, Mod­ erate dmnage was observed on the crest of the Snowbird Mountains, east of Old Billie Top, and the Valley River Mountains, Clay County: Light damage was observed north of Ogden and Chatuge Lake, Moderate defoliation occurred in the Fires Creek Section on the crest of the Tusquitee Mountains and from Signal Bald to Tuni Gap. Moderate feeding was also observed in small patches on the slopes of Chunky Gal Mountain, Macon County: The eastern boundary of light defoliation ran along the upper edges of the Blue Valley to Brush Mountain and Satulah Mountain south of Highlands and north to Cowee Bald, Moderate damage occurred on the eastern slopes of the Nantahala Mountains, The area surrounding Aquone Reservoir, which was heavily defoliated in 1961, was light in 1962. Graham County: Light defoliation occurred over the entire county and moderate damage occurred on most of the high ridges east of Robbinsville including the Snowbird, Yellow Creek, and Cheoah Mountains, Moderate defoliation also occurred on the ridges surrounding Santeetlah Creek and Santeetlah Lake, Heavy defoliation occurred in scattered patches along the Swain County line from Cheoah Bald to Round Top, Swain County: Light damage occurred east to Alarka and Jackson Line l I mountains, Defoliation appeared for the first time in the Great SmokY Mountains National Park, the light boundary extending from Deals Gap along Dalton Ridge, Round Mountain Knob, Paw Paw Ridge, Augerhote Gap, Hazel Creek, High Rocks, and Pilot Ridge, Approximately 3,452 acres of moderate damage occurred within the National Park on Twenty-Mile Ridge and Welch Ridge, In addition, moderate defoliation was found in the Nantahala Gorge and along the Macon County line, South Carolina Oconee County: Elm spanworm damage appeared for the first time in South Carolina, All damage was light, the boundary running from Callas Gap south to Round Mountain and Lake Yonah. The most severe damage occurred near Tusallou Lake where individual hickories were stripped,

There was a decline in both total acres defoliated and intensity of d9fo­ liation by elm spanworm in 1962. The movement of the outbreak continued in a northerly and easterly direction, extending into the Great Smoey Mountains National Park and South Carolina and declining in parts of Termessee, the extreme western portion of North Carolina, and portions of Georgia.

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