Downy mildew causes problems on various plants including alyssum, carnation, pansy, poppy, snapdragon, sunflower, and sweet pea. Downy mildew causes soft and fluffy gray, purplish, or light brown sporulation on the underside of leaves and sometimes on stems or buds. Pale yellow areas or irregular purplish red to dark brown necrotic lesions are sometimes visible on the upper surface of infected leaves.
Solutions
Provide good air circulation and maintain low humidity. Avoid wetting foliage; use drip instead of overhead irrigation where feasible. Dig out infected plants as soon as possible to reduce the spread of disease. Several fungicides can prevent infection of healthy tissue, and fungicide use may be necessary to prevent damage to susceptible plants if conditions are good for disease development.
