Forest Health Protection and March 2010 State Forestry Partners

7.6 WEB July 2010 Management Guide for R. Ladd Livingston Balsam Woolly Adelgid Lee Pederson, US Forest Service piceae (Ratzeburg)

Topics Subalpine is most susceptible. Grand fir is most resistant to damage. Overview 1 All true may be hosts. Life History 2 Natural Control 2 This European invader was first found in northern Idaho in 1983. It has expanded south to the Silvicultural 3 Alternatives Sawtooth National Forest, killing substantial numbers of subalpine fir. Chemical Control 3 Recognizing 4 adelgid damage Damage depends on population density Other Reading 4 Balsam woolly adelgid was around the buds and branch nodes. Field Guide discovered in northern Idaho in All sizes of trees are attacked. 1983 feeding predominantly on but the infestations may be Management Guide Index subalpine fir and to a less extent, concentrated on the stems or in the grand fir. Since that time, it has crowns. Stem-attacked trees can die been found from the Canadian after only 2-3 years of heavy border to as for south as the infestation and without any apparent Sawtooth National Forest in Idaho. gouting. Key Points It has caused extensive mortality of In the crowns, gouts occur on  It is a non- subalpine fir, especially in low- the fastest growing parts of the tree, native species elevation drainage bottoms. and on trees that have been lightly that has only Nymphs feed on the bark of stems, infested for a long time. These trees been known in branches, and twigs, and at the decline slowly, growth is reduced, Idaho since base of new shoots and buds, but and the dead and dying upper stem is 1983. never on needles. Their feeding often infected by -destroying  We know little causes stunting of terminal growth fungi. about its real with distinct swellings (gouting) potential for ecological damage.  Natural and An Invasive Species environmental  This is still advancing in Idaho and mortality is increasing. influences have

not stopped its  It causes tremendous ecological changes on low elevation subalpine spread. fir sites.  Silvicultural management  Control at stand or landscape levels is not feasible with insecticides. may reduce Individual tree protection with an approved insecticide can provide damage. effective control. Page 2 Back to Menu Balsam Woolly Adelgid 7.6

Life History Balsam woolly adelgid wool. The egg laying period can generally overwinters in the first last about 6 weeks. instar (neosistens) of the Crawlers (first instar nymphs) Balsam woolly hiemosistens generation. They are emerge from the eggs and settle on adelgids insert their about 0.35 mm long, amber the bark during July. These mouthparts into the colored, flattened. and fringed with neosistens of the new cortical parenchyma of wax. They can be found on any aestivosistens (summer) generation the bark. part of the tree where the bark is go into a dormant period for

A chemical in their thin enough for them to reach the several weeks then start feeding saliva affects the conductive tissue (cortical and develop into adults by late hormonal action of the parenchyma). About May they summer. tree. start feeding, go through two more Egg laying can occur from late instars, and change into adults by August to late October. and This causes abnormal June. nymphs from these eggs cell division and Adults are all females and are overwinter. Two generations a year differentiation in the about 1 mm long, dark purple to commonly occur in the bark and newly formed black, wingless, and become mountainous areas of the West. wood. covered with whitish “wool”. Up Three to four generations can

to 250 eggs can be laid under the occur in milder climates. Abnormally wide annual rings are produced in the stem, which are composed of thick cells Natural Control (compression wood). Hosts: Heavy balsam woolly adelgid feeding modifies the Stunting of terminal bark and after a few years they can't penetrate the thicker growth also occurs, layers. Attractive feeding space on the tree diminishes and with distinct swellings populations die out. If a tree survives the initial infestaton, around the buds and mortality will likely be avoided. branch nodes. Weather: Freezing is fatal and chances are increased as o o The abnormal swelling temperatures fall below -5 F. There are no survivors at –30 F. is called “gouting”. Adelgids below the snowline usually survive. Cold, wet springs can reduce populations of developing nymphs. Abnormally cold periods in the fall will also decimate populations.

Biological: North American predators are not very efficient, so three beetles and three flies were introduced from Europe and have become established. Balsam woolly adelgid populations increase so rapidly that these predators have been shown to be virtually ineffective. 7.6 Back to Menu Balsam Woolly Adelgid Page 3

Silvicultural Alternatives Along the West Coast the most  Take into account prevailing severe outbreaks occurred at the wind direction when establishing lower end of the host species cutting boundaries. elevation range, i.e.. from 3,000-  Fall infested trees away from non 5,500 feet in subalpine fir and below -infested ones. 1,000 feet in grand fir. Although we  Clean all logging equipment There are few do not have anything below 1000 before moving it to new areas. effective feet, elevational restrictions may  Cut and remove infested trees in measures for exist in the Northern Rocky winter when nymphs are not prevention Mountains also. motile. through forest  Don't establish nurseries in the management The literature indicates there are vicinity of infested stands. practices. not many effective measures of Inspect outgoing seedlings for prevention through forest aphids. management practices. Under intensive forest management, the 2. Grow fir on short rotation following measures may reduce cycles. damage: 3. Favor other non-host species. 4. Selective cutting and removal 1. Slow the rate of infestation of heavily infested trees. spread that is caused by crawlers 5. Maintain full stocking and being transported by the wind or increase vigor of stands. carried on logs and vehicles, and 6. Introduce or develop less nursery stock: susceptible species of firs, and  Refrain from moving infested genetically resistant strains or logs through non-infested stands. hybrids.

Chemical Control Insecticidal sprays have to drench this insect which is fairly well hidden on the tree. Thus, aerial spraying is unfeasible.

There are five insecticides registered for balsam woolly adelgid control in Idaho (as listed in the Pacific Northwest Insect Management Handbook 2009).

 Carbaryl  Chlorpyrifos (Lorsban 4E): A restricted use pesticide.  Endosulfan (Thionex 3EC, Thionex 50W): Nursery use only.  Imidacloprid (Provado 1.6F)  Sucrose octanoate (SucraShield): A sugar based insecticide/ miticide/ovicide that quickly acts to desiccate or suffocate the target insect.

Always check for current registration and restrictions before using any of the chemicals listed above. Page 4 Back to Menu Balsam Woolly Adelgid 7.6

Recognizing Balsam Woolly Adelgid The most obvious indicator of with a concurrent stunting of balsam woolly adelgid presence is growth is another symptom. If the the white “wool" covered females gouts enclose reproductive buds, on the bark of stems or branches. no new shoots or needles are This is most noticeable during produced. summer months. Dying or dead branches and Swellings of the outer branch crowns are other symptoms. nodes and terminal buds (gouting) Internet Resources

White “wool”- covered http://insects.ippc.orst.edu/pnw/insects female balsam woolly http://www.oregon.gov/fh/BalsamWoollyAdelgid.pdf adelgid on the bark of a http://www.fs.fed.us/r6/nr/fid/fidls/fidl-118.pdf subalpine fir. http://cru.cahe.wsu.edu/CEPublications/eb1456/eb1456.html Other Reading Balch. R.E. 1952. Studies of the Balsam Woolly Aphid. Forest Health Protection and State Adelges piceae (Ratz.) and its effects on balsam fir. Forestry Organizations (L.) Mill. Can. Dept. of Ag., Pub. 867, 76 p., illus. Assistance on State Assistance on And Private Lands Federal Lands Livingston. R.L., and J. Dewey. 1983. Balsam Woolly Aphid. Report of an Idaho infestation. Idaho Dept. of Montana: (406) 542-4300 US Forest Service Region One Lands and USDA For. Serv., Northern Region. IDL Idaho: (208) 769-1525 Missoula: (406) 329-3605 Rpt. No.83-7. 9 p., illus. Coeur d’Alene: (208) 765- Utah: (801) 538-5211 7342 Pederson, L., J. Fidgen, L. Lazarus, D. Beckman, B. Burkhead, and N. Kittelson. 2010. Distribution of Nevada: (775) 684-2513 US Forest Service Balsam Woolly Adelgid in Idaho: numbered report Region Four Wyoming: (307) 777-5659 in Draft. USDA-Forest Service, Forest Health Ogden: (801) 476-9720 Boise: (208) 373-4227 Protection, Coeur d’Alene Field Office. N. Dakota: (701) 228-5422 Ragenovich, I.R. and R.G. Mitchell. 2006. Balsam Woolly Adelgid. USDA Forest Service, For. Pest Leaf. 118. 12p., illus.

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