Carrots: the leaves may survive despite fungus infection. Harvest losses are usually within acceptable economic limits but in isolated cases however, can be up to 40%. Parsley: infected leaves are not marketable.
Higher occurrence in dry years with above-average sunshine. High humidity at dawn and dusk promotes fungi spread.
The dense, white powdery fungus growth typical for powdery mildew is found on leaves, stalks, and flowers. (Pictures 1 & 2) The disease is wind dispersed and usually infects older leaves first.
Incorporate infected crop residues and practice good crop rotation. Avoid excess nitrogen fertilizer. Sprinkling by overhead irrigation may reduce the amount of damage. At the onset of infection, chemical treatment with fungicide may be useful.