Downy mildew of rose
Apr 16, 2011 7:14 AM
Oomyecte Causal agent: Peronospora sparsa
Symptoms: The disease occurs under cool, moist, and cloudy conditions. The unique symptom on roses are the purplish to reddish irregular spots on the leaves. At the advanced stage of the infection, the leaves turn yellow, and brown dead areas within the purplish blotches. In severe cases purplish patches can be seen on the branches. Under favorable conditions, spore masses can be seen on the lower surface of the leaves and on canes.
Management: Use resistant varieties whenever possible. Allow sufficient air circulation and plant in areas with full sunlight. Avoid overhead irrigation during conducive conditions for the spread of the disease. Remove all the dead leaves and branches from the plants. Sterilize the pruning knives to prevent the spread of the disease.
Various fungicides are available for management. Check http://premier.cdms.net/webapls/formsloginRef.asp?/webapls for current labels