It’s the time of year when powdery mildew raises in its dusty, unattractive and growth-sapping cloud. It’s the most common and widespread of fungal diseases, attacking both fruit trees, ornamentals and vegetable plants. Controlling it presents special challenges to the organic gardener. And this summer’s weather patterns — warm and dry — tend to favor its spread.
With its patchy, gray, talcum-like dust that covers leaves and stem, powdery mildew is easy to spot. Detecting it early is one of the many reasons to regularly give your plants close inspection. Once it turns black, which signifies that it’s starting to fruit, you’ll have real problems controlling it from spreading. While the fungal threads that make up powdery mildew stay on a plant’s surface and aren’t as harmful as some other diseases, they can retard growth and affect flavor, especially on fruits. Controlling powdery mildew starts in the spring by choosing plant varieties that are resistant to the fungus. Give your mildew-susceptible plants plenty of room so that air can circulate between leaves and stems. (more…)