Plant Disease Management Handbook

Cause The fungus, Erysiphe heraclei, was reported on chervil production in California. Testing by University of California Cooperative Extension showed that strains of E. heraclei from chervil did not infect either celery or parsley. Cleistothecia were not observed.

Cause Pythium, Globisporangium, and Fusarium spp. can cause root rot and seedling blight known as damping-off. These soilborne fungi and fungus-like microorganisms can persist indefinitely in soil or plant debris. Pythium and Globisporangium are favored by wet soils.

Cause Golovinomyces depressus has been reported from Idaho and observed many times in western Oregon on Centaurea montana. These are highly specialized pathogens that form a close association with the host. Conditions that favor the host also tend to favor the pathogen. Overcrowding of plants is also favorable for disease development.

Cause There are 8 different species of Puccinia reported from the PNW on Carex sedges. Sedges are the telial host while the alternate host is variable and dependent on the rust species. Uromyces perigynius is another rust reported from Oregon and Washington.

See:

Barley (Hordeum vulgare) - Stripe Rust

Cause Numerous species of fungi, including Alternaria, Fusarium, and Helminthosporium spp. They infect kernels during seed maturation, especially green kernels, and are favored by high relative humidity or rainfall. Some fungi can be pathogenic on seedlings that develop from infested seed.

Cause The fungus, Fusarium oxysporum f. sp. medicaginis, is a vascular fungus that can survive in soil indefinitely as durable spores (chlamydospores) or in association with plant debris. Seed can also transmit Fusarium wilt, usually by contamination of the seed coat.

Cause A fungus-like microorganism, Aphanomyces euteiches, that overwinters as thick-walled oospores, which can be spread by water, wind, infected plant debris, soil movement, or tillage equipment. Oospores are produced within infected root tissue, which decomposes, releasing the oospores into surrounding soil. The fungus can infect and multiply in other legume roots, such as clover, pea, lentil, Cava bean, and common bean.

Pertaining to the absence of life; abiotic diseases are not caused by living organisms (biotic pathogens), but by chemical and/or physical factors.

The curved, apical portion of a blighted stem typical from bacterial infections.