Powdery Mildew
(click image to enlarge) Symptoms:
• White, powdery mats of mycelium
• Appears first on older, lower leaves
Epidemiology:
• Favored by warm temperatures (59-86° F)
• Optimum of 77° F
• Favored by high relative humidity without free water on leaf surface
• Greater damage in water-stressed plants
• Susceptibility increases with plant age
Control:
• Fungicide applications before disease onset when temperatures and relative humidity become conducive for infection
• Consider fungicide resistance management by including sulfur as tank-mix partner