Powdery Mildew

It is a fungal disease caused by many different genera including Erysiphe, Sphaerotheca and Uncinula among others, all known as powdery mildews. They are specific to their hosts and one type will infect only certain plants, usually those in the same or closely related plant families. It is favored by moderate or high humidity and low light intensity, conditions which are often prevalent on lower parts of plant or in dense foliage.

Host;

They include; tomatoes, potatoes, capsicum, carrots, peas, cucurbits, citrus, mangoes, onions, wheat family among others.

Symptoms;

Most powdery mildews are recognized by white to gray powdery spots or large blotches on the surface of leaves, stems and fruits of host plant. The white powdery growth consists of the fungal mycelium and asexual reproductive spores.

Powdery white fungal growth initially appears on the oldest leaves but spreads to cover all leaf surfaces.

Fungi are spread by airborne spores, transported by wind or pests which land on leaves and germinate. Powderly mildew needs plant tissues in order to grow, but they don’t directly kill the host plant. Rather, they feed on the plant’s cells. Infected foliage becomes brittle and distorted and the petioles turn brown and die. Yield is reduced and petiole breakage affects mechanical harvesting.

Cultural control includes resistant varieties and removing crop debris after harvest.

Chemical control method includes use of any of the products:

Good control of powdery mildew is achieved by alternating the above products as they have different active ingredient. Alternating is also advocated as a disease resistance management strategy.