Plant Disease Management Handbook

Cause A fungus, Stagonosporopsis caricae (syns. Stagonosporopsis citrulli, Stagonosporopsis cucurbitacearum, Didymella bryoniae, Phoma cucurbitacearum), which overwinters in associaton with infected crop debris for at least two years. This fungus can also be seedborne. Numerous other cucurbits are affected, including cantaloupe, cucumber, squash, and pumpkin.

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Radish (Raphanus sativus) - White Rust

Seed Crop, Crucifers (Brassica, Eruca, and Raphanus spp.) - White Rust

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Fir, Douglas and True - Stem Decays (Heart Rots)

Fir, True (Abies spp.) - Heterobasidion Root Disease

Cause A fungus, Mycosphaerella brassicicola, attacks Brussels sprouts, broccoli, cabbage, and cauliflower. The disease is a problem mostly in seed production fields. Seeds may carry the pathogen. The fungus also overwinters on infected weed and crop hosts or in residues. Spores spread by wind. Cool (59°F to 70°F) moist weather favors disease development.

Cause The fungi or fungus-like microorganisms, Pythium spp., Fusarium spp., and Rhizoctonia solani, attack young seedlings of many vegetables, including members of the genus Brassica. These soilborne microorganisms can persist indefinitely in soil or plant debris. If seedlings are affected before emergence, it appears as poor germination.

Cause Alternaria radicina and potentially Alternaria dauci have been reported on parsnip in the US and Canada. Alternaria species can be seedborne. Once this fungus is introduced to a field, it survives on non-decomposed plant debris. Disease is promoted by wet leaves and high relative humidity. Spread occurs with wind, splashing water (wind-driven rain, dew drips, irrigation), and by mechanical means (tools or workers).

Cause Alternaria petroselini and potentially other species have been reported on parsley in the US. Alternaria species can be seedborne. Once this fungus is introduced to a field, it survives on non-decomposed plant debris. Disease is promoted by wet leaves and high relative humidity. Spread occurs with wind, splashing water (wind-driven rain, dew drips, irrigation), and by mechanical means (tools or workers).

Cause The fungus, Venturia oleaginea (anamorph: Spilocaea oleagina), occurs across the world where olives are grown. The fungus is thought to primarily reproduce through the production of conidia (asexual spores) and survives as infected leaves that remain on the tree. Conidia are moved by water and wind. Disease is promoted by wet conditions and moderate temperatures (41 to 77°F).

See:

Radish (Raphanus sativus) - White Rust

Seed Crop, Crucifers (Brassica, Eruca, and Raphanus spp.) - White Rust

See:

Seed Crop, Crucifers (Brassica, Eruca, and Raphanus spp.) - Black Rot