Plant Disease Management Handbook

Cause Fungal growth at the base of various conifers during the PNW rainy season has been repeatedly identified as Coniophora sp. Coniophora puteana is a known root and butt rot pathogen causing a brown rot decay of Engelmann spruce (Picea engelmannii) and other forest conifers. In the landscape, this growth has not been associated with decline, rot or structural problems of trees.

Cause Streptomyces scabies (syn: Streptomyces scabiei), a filamentous bacterium that lives in soil and can infect storage root and tuber portions of beets, potatoes, parsnips, carrots, radish, and potentially other root and tuber crops. Neutral or alkaline soils favor common scab development, it survives a short period of time in acidic soils. Soils containing high levels of organic matter which is not fully-decomposed, can have more severe disease.

Cause Streptomyces scabies (syn: Streptomyces scabiei), a filamentous bacterium that lives in soil and can infect storage root and tuber portions of beets, potatoes, parsnips, carrots, radish, and potentially other root and tuber crops. Neutral or alkaline soils favor common scab development, though it survives a short period of time in acidic soils. Soils containing high levels of organic matter which is not fully-decomposed, can have more severe disease.

Cause Unknown. Diseased tissue is negative for Phytophthora organisms. Many different secondary fungi have been isolated including a Phomopsis sp. The bacteria Lonsdalea sp. has also been isolated from branch cankers. Sequencing placed it close to L. quercina, the cause of a disease known as drippy blight of oaks.

A thin-walled spore produced by rust fungi which can function as primary or secondary inoculum and are spread by wind or wind-blown rain. These spores can be repeatedly produced throughout the growing season, depending on the specific rust fungus, and are borne in yellow-, orange-, or brown-colored pustules (uredinia).

An aggregate of resting spores present in soil or plant structures, such as the clusters with hundreds of spores that are produced by Spongospora subterranea (causal agent of powdery scab in potato).

Cause A few fungi have been found in association with leaf spots on spirea (Spiraea spp.) in the PNW.

See:

Rhododendron - Cutting Rots

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Camelina (False Flax, Gold of Pleasure)

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Squash (Cucurbita spp.) - Toxic Squash (Toxic Zucchini)