Downy mildew of vegetables, fruits, ornamentals, forages, and field crops, Blue mold of Tobacco.
Downy mildews are primarily foliage blights that attack young, tender leaves, twigs, and fruits.
Downy mildew of grape, spinach, and tobacco cause serious economic losses. It spreads rapidly through fields and is dependent on a wet, humid environment with cool or warm, but not hot, temperatures to grow and infect. A film of water is needed on plant tissue for spore germination and infection. Downy mildew fungi are related to Pythium and Phytophthora . Symptoms of downy mildew infection include small, pale yellow spots with indefinite borders on the upper leaf surface.