Bonide Copper Fungicide RTU - Manual (Page 7)

Powdery mildews tend to occur on the upper leaf surfaces, as though a white powder
was sprinkled onto the plant. Powdery mildews can form a dense, white, cottony mass,
making the whole leaf appear white. They are also commonly found on stems. Powdery
mildews rarely kill plants. Most fungal diseases require water to infect plants. Powdery
mildews are unique in that they do not require water for infection. Hence, under home
greenhouse conditions, powdery mildews can become severe. Shade and dense
plantings also promote powdery mildew.
Powdery mildews commonly occur on the following plants: bean, beet, broccoli,
brussel sprouts, cauliflower, cabbage, cantaloupe, chard, chicory, chive, cucumber,
currant, endive, gooseberry, hop, kale, kohlrabi, lettuce, lilac, pea, pumpkin, rose,
rutabaga, spinach, squash, strawberry, turnip, zucchini and many other plant species.
Downy mildews tend to occur on the lower leaf surfaces. Downy mildews are much
finer than powdery mildews, and appear as fine white cotton, similar to duck down.
Downy mildews can rapidly kill plant leaves during wet, cool weather, but are inhibited
by hot dry weather. White rust is caused by fungi related to the downy mildews and
occurs as small white blisters, full of white powder, that appear on plant leaves. The
white powder is rust spores.
Downy mildews commonly occur on the following plants: bean, beet, broccoli, brussel
sprouts, cauliflower, cabbage, cantaloupe, chard, chicory, chive, corn, cucumber,
endive, garlic, hop, kale, kohlrabi, leek, lettuce, onion, pea, pumpkin, rutabaga, shallot,
spinach, squash, sunflower, tobacco, turnip, zucchini and many other plant species.