The fungus “Erysiphe polygoni” causes powdery mildew of beans and peas.
The disease causes white powdery patches to appear mainly on the older
leaves and stems of plants.
SYMPTOMS OF POWDERY MILDEW
White powdery patches appear on both sides of the leaves. Young leaves
are almost immune. A large part of the talc-like powder on the leaf
surface is composed of spores. These spores are easily blown by winds to
nearby susceptible plants.
Heavily infected leaves become yellow, then become dry and brown, before
dropping off. If the leaves drop off, the beans will not fill much
further. The pods are covered with white patches which may develop
purplish spots and become distorted .
The powdery mildew fungus can reproduce under relatively dry conditions.
Increased humidity can increase the severity of the disease, and
infection is worse during periods of heavy dew.
CONTROL OF POWDERY MILDEW
* Attacks of powdery mildew occur in dry seasons and are worst in
sheltered gardens.
* It is not known how the fungus survives between crop seasons, &
crop rotation and many other cultural practices seem to have
little effect on the incidence of powdery mildew.
* Peas & beans need fertile soil. Plants grown in poor soil, without
correct applications of fertiliser, will develop powdery mildew
before well fed plants. Healthy, vigorous leaves and stems are
less prone to infection.
* Mildew resistant varieties of peas & beans reduce the problem of
the disease.
* Chemical sprays are available to control mildew. Always follow the
instructions on the packet.
The fungus “Erysiphe polygoni” causes powdery mildew of beans and peas.
The disease causes white powdery patches to appear mainly on the older
leaves and stems of plants.
SYMPTOMS OF POWDERY MILDEW
White powdery patches appear on both sides of the leaves. Young leaves
are almost immune. A large part of the talc-like powder on the leaf
surface is composed of spores. These spores are easily blown by winds to
nearby susceptible plants.
Heavily infected leaves become yellow, then become dry and brown, before
dropping off. If the leaves drop off, the beans will not fill much
further. The pods are covered with white patches which may develop
purplish spots and become distorted .
The powdery mildew fungus can reproduce under relatively dry conditions.
Increased humidity can increase the severity of the disease, and
infection is worse during periods of heavy dew.
CONTROL OF POWDERY MILDEW
* Attacks of powdery mildew occur in dry seasons and are worst in
sheltered gardens.
* It is not known how the fungus survives between crop seasons, &
crop rotation and many other cultural practices seem to have
little effect on the incidence of powdery mildew.
* Peas & beans need fertile soil. Plants grown in poor soil, without
correct applications of fertiliser, will develop powdery mildew
before well fed plants. Healthy, vigorous leaves and stems are
less prone to infection.
* Mildew resistant varieties of peas & beans reduce the problem of
the disease.
* Chemical sprays are available to control mildew. Always follow the
instructions on the packet.