Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Susan K. Hagle – Plant Pathologist,
Scott Tunnock – Entomologist (retired),
Kenneth E. Gibson – Entomologist, and
Carma J. Gilligan – Biological Technician.

U.S. Department of Agriculture, Forest Service, State and Private Forestry, Northern Region, P.O. Box 7669, Missoula, Montana 59807. 1987. Reprint 1990. Publication Number R1-89-54.

II.  Key To Common Abiotic Damages

	1.  Top broken – 2
	1.  Top not broken – 3
		2.  Evidence of canker or internal decay	(See Key I,section A)
		2'.  No evidence of canker or decay	Snow or Wind Breakage
	3.  Seam or narrow scar vertical on stem; at least several feet long – 4
	3'.  No seam or scar as described – 5
		4.  Seam or scar spiraling around stem, down from the top of the tree	Lightning
		4'.  Seam or crack not spiraling, nearly vertical	Frost Crack
	5.  Damage restricted to buds or new shoots		Frost Injury
	5'.  Damage in year-old or older foliage – 6
		6.  Damage to year-old foliage restricted to portions of tree above snow level or      on south or west aspects of crown; new growth in spring is green, normal	Winter Dessication
		6'.  Damage general throughout crown; weak, drooping shoots; loss of older      foliage; little or no growth	Drought Injury

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