Vespula pennsylvanica / maculiforna / germanica / vulgaris / squamosa and DolichovespulaThe dog days of summer…fresh water melon, ice cream, p
06.06.2023 - 19:05 / gardenerspath.com / Helga George
How to Control White Leaf Spots on Cruciferous Vegetables Cercospora / PseudocercosporellaWhile the fungi Cercospora or Pseudocercosporella that cause white spot can severely affect turnip, rutabaga, canola, mustard, radish, horseradish, and hybrids of turnips and mustard, they are much less likely to affect kale, collards, broccoli, or cauliflower.
This is a cool weather disease and is most likely to strike at 55 to 65 F.
The disease has been a particular problem on canola plants in Europe with pod losses of up to 15%.
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Cultural treatments are the best way to control this disease, and the discussion below will walk you through the symptoms, life cycle, and control measures of white spot disease on crucifers.
SymptomsWhite spot disease gets its name from the circular white spots that are scattered over the leaves, stems, or pods of infected plants. Older spots may develop dark borders, and the centers may fall out. Such lesions look like shot holes.
In addition to turning yellow, leaves that are severely affected dry out and wither, although they remain attached to the plants.
Lesions on the stems are superficial with a distinct boundary between tissue that is diseased or healthy. The lesions start out brown and then turn ash-gray to white. Large numbers of tiny dark specks form in the lesions, which are known as gray stem.
Infected seed pods start out with small brown spots. They then expand and become grayish-white with dark spots inside.
Cool Moist Conditions Favor Disease DevelopmentThe remains of infected plants are a significant source of spores to spread the disease. The wind can spread the sexual spores long
Vespula pennsylvanica / maculiforna / germanica / vulgaris / squamosa and DolichovespulaThe dog days of summer…fresh water melon, ice cream, p
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