OTHER STRESSORS

Other stressors of high elevation pines include needle casts and blights, seed and cone disease and/or insects, and stem and/or root decays. Although these stressors may not pose a large threat to white pine ecosystems, in great quantity any one of these can weaken the natural defenses of a tree and make the tree more susceptible to other damaging agents.

Needle casts and blights

A variety of different needle casts and blights have been observed on high elevation white pines. Very little is known about these diseases and the impact that they have on these species. Although the symptoms vary greatly, they may appear as chlorotic (yellow) spots on the foliage or the needles can brown and be shed (cast) early as a result of infection. The rate of development is variable but is favored by warm wet weather.

Some of the observed foliage diseases include:

Fungal needle cast (Lophodermium durilabrum)
Needle blight (Dothistroma septospora)
General info on foliage diseases

Seed and cone disease and/or insects

High elevation pine cones and seeds are exposed to insects and diseases that reduce cone and seed production and diminish the natural regeneration capacity.

Some insects of cones and seeds include:

Cone moths/worms (Dictyctria spp. and Eucoma spp.)
Cone beetles (Conophthorus spp.)
Seed chalcids (Mefastigmus spp.)
Seed bugs (Leptoglossus spp.)

Seed and cones diseases include:

Seedborne fungus (Siroccocus stobilinus)