Powdery Mildew
(fungus - Sphaerotheca pannosa var. rosae): A white powdery growth
develops on leaves, buds and twigs causing them to be distorted and dwarfed. Young,
tender growth is most susceptible. The disease is more likely to occur during
cool, dry conditions and can spread rapidly since a complete life cycle can occur
in 72 hours. Thousands of spores are produced on a single plant with each having
the ability to cause disease. Varieties differ in their susceptibility. Use an
appropriate fungicide during times when disease pressure is high.
