Phytophthora Root Rot, Phytophthora/Pythium Root Rot, Pitch Canker

Nursery Insects and Diseases Phytophthora root rot,

Phytophthoro spp.

Region 6: Oregon, Wasbington Host(s): Conifers

At one nursery, l+l larch seedlings had a high incidence of Phytophthora. root disease. One-third of two seedbeds was lost to root rot. Losses were associated with higher than normal rainfall, heavy /poorly drained soils, and root wrenching stress. At another nursery, the weather was cool, but dry; resulting in little detectable Phytophthora.

Phytophthora/Pythium root rot, Phytophthoro spp.,

P11thium spp.

Region 4: Idaho, Utah Host(s): Douglas-fir, spruce

These fungi occured on seedlings and in soil at the Lucky Peak Nurs ery, Boise National Forest, Idaho, and the Lone Peak Nursery in Utah. Infection resulted in frequent mortality and culling of 2-0 seedlings.

Pitch canker,

Fusarium subglutinans

Region 8: North Carolina, Host(s): Longleaf pine, shortleaf pine, slash pine, Virginia pine Tennessee Pitch canker was first identified as a tree pathogen on Virginia, short leaf, and pitch pine in 1946. Since then Fusarium subglutinans has been found to infect vegetative and reproductive structures. The pitch canker pathogen was proven to cause cone mortality and deterioration of seed in slash, Virginia, shortleaf, and longleaf pine orchards. Pitch canker has also been reported to cause damping-offof southern pine seedlings, and to cause seedling related mortality in first year pine seedlings. This fungus has proven to be a problem in shortleaf seedlings from mountain source orchard seed in Edwards State Nursery in North Carolina.

Poplar and Willow Borer, Cr11ptorh11nchus rapathi

Region 6: Oregon Host(s): Willow

Willow stool beds at the J. Herbert Stone Nursery are infested by this borer. Current infestation is sparce, but contingencies are ready if the damage level increases in 1994.