Frost Injury
From Bugwoodwiki
Contents |
Host
All conifers can be damaged but true firs, Douglas-fir, western and subalpine larches, western and mountain hemlocks, and Engelmann spruce are most often damaged.
Distribution
Occasional throughout Idaho and Montana but sometimes chronic on high elevation sites and in frost pockets.
Damage
New shoots or needles of breaking buds are killed. Growth may be stunted and tree form may be damaged when terminal buds are killed.
Identification
Depending upon the stage of development of shoots at the time of the frost, buds which are just breaking dormancy, needles of new growth, and succulent shoots may be killed. Within a day or two of frost damage, foliage and shoots become limp and begin to fade to yellow. After a week or more, the foliage is red and drooping on the branch or dead shoot (fig. 145). Dead buds become dark brown in the interior.
Frost damage may be most severe in the upper crowns of small trees because this is generally the first part of the crown to break dormancy. Damage often occurs in several species in the same stand.
Similar damages
Shoot blight of subalpine fir caused by Delphinella looks very similar to frost damage but is most severe in the lower crown while frost damage is often more severe higher in the crown. Microscopic examination may be required to confidently discern between them.
References
Bega, R. V. 1978. Diseases of Pacific Coast conifers. USDA For. Serv. Ag. Hndbk. No. 521, 206 p.
Boyce, J. S. 1961. Forest Pathology. McGraw-Hill Book Co., New York, NY. 572 p.
Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54
