Plant Disease Management Handbook

Note Several nursery plants with stem cankers have been sent into the OSU Plant Clinic. It is suspected that most are due to cold injury followed by secondary invasion by various fungi (such as Fusarium lateritium or Phomopsis sp.), oomycetes (mainly Phytophthora spp.) or the bacterium Pseudomonas.

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Sword Fern (Polystichum munitum) - Die-off

Cause The only fungus reported on sweet gum in the PNW is a leaf spot caused by Cladosporium sp. from Oregon. The OSU Plant Clinic has gotten many leaf spot samples on sweet gum in June which are likely seen earlier in May. Many of these leaf spots are abiotic while others yield a wide variety of fungi and bacteria including Alternaria, Cercospora, Leptothyvella (red leaf spot), Septoria, and even Pseudomonas.

Note: There are almost no reported fungi on sweet gums in the PNW. The OSU Plant Clinic has found a few fungi that tend to be opportunistic on injured shoots and branches. Injuries may be due to such events as winter injury. These fungi include Cytospora and Nectria. The Botryosphaeria canker found in eastern and southern states has not been found in the PNW.

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Cabbage and Cauliflower (Brassica sp.) - Yellows (Fusarium Wilt)

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Turnip and Rutabaga (Brassica sp.) - Wilt (Fusarium Wilt {Yellows}, Verticillium Wilt)

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Radish (Raphanus sativus) - White Rust

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Cabbage and Cauliflower (Brassica sp.) - Powdery Mildew

Radish (Raphanus sativus) - Powdery Mildew

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Cabbage and Cauliflower (Brassica sp.) - Clubroot

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Turnip and Rutabaga (Brassica sp.) - Clubroot

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Turnip and Rutabaga (Brassica spp.) - Sclerotinia Stem Rot and Watery Soft Rot

Cause Sclerotinia sclerotiorum is a cosmopolitan fungus that occurs across the globe, infecting a very large number of plant species including parsley crops. Other susceptible host plants include bean, carrot, pea, lettuce, potato, green pepper, cucurbits, parsnip, radish, sunflower, herbs including mint, fruit trees including apple, nectarine, and sweet cherry, and a large number of ornamentals both woody and herbaceous. Weeds can also be host to S.