Avoid high plant densities

Sunflower is one of the largest produced oilseed crops in the country annually. Though it is grown on a large scale for oilseed production in India the crop suffers huge losses due to many pest and disease outbreaks.

Especially during the flowering and grain formation stages sudden outbreak of diseases like the powdery mildew infects crop growth and yield.

Symptoms

The disease produces white powdery growth on the leaves. White to grey mildew appears on the upper surface of older leaves.

As plants mature black pin head sized are visible in white mildew areas.

Infested leaves lose lustre, curl, become pale in colour and die.

The disease appears on the upper surface of leaves in the form of pale yellow or pale brown minute discoloured specks from which powdery mass radiates to all sides of leaves.

Heavily infested leaves dry and shed prematurely.

Soon these specks get covered with whitish powdery mycelial growth which increase in size and develop to cover much of the plant area with white powdery growth.

Gradually, the infection spreads to other parts of the plant. The disease is prevalent more under dry conditions especially at the end of the winter months.

Management

— Reducing the likelihood of a disease outbreak is more effective than trying to control the disease once it is established.

— Avoid growing crops in situations of high humidity.

— Morning watering limits the build-up of humidity in the crop overnight.

— Avoid high plant densities which leads to heavy infection.

— Application of sulphur dust at 25-30kg/ha or calixin 1 ml/litre is found effective in reducing the disease incidences.

— Under high incidences spraying of difenoconazole 1ml/litre is very effective.

(Mallikarjun Kenganal is assistant professor, Agricultural Extension Education Centre,University of agricultural sciences, Raichur, email: mallikarjun_nss@rediffmail.com, mob: 09845364708.)