botrytis

Botrytis blight is a cruel disease for flower gardeners, because it strikes garden plants in their prime, destroying blossoms just as they are ready to open. Botrytis, also called grey mold, is a fungal disease, and gardeners can recognize it when they see these symptoms in plants:

Spotting or discoloration on leavesWilting or decaying leaves and shootsLeaf dropFuzzy grayish brown growth on flowers and foliageFlower buds that fail to openRotting flower buds

Botrytis thrives in high humidity and cool weather, so gardeners will see signs of grey mold most often in spring.

In the outdoor flower garden, peonies and roses are the most likely plants to show signs of botrytis. In the greenhouse, several flowers are susceptible to this fungus, especially:

Sulfur powders and sprays are effective at controlling fungal diseases like botrytis in the flower garden. Apply sprays early in the morning or evening to avoid harming bees or beneficial insects.

A less common, but very effective organic treatment against foliar diseases in the flower garden is the bacterium Bacillus subtilis, sold under the trade name Serenade. Many gardeners report that they like the fragrance of this spray compared to other organic or conventional fungicide sprays.

When you notice the first signs of botrytis in the flower garden, get out the clippers. Remove all affected foliage and flowers, and destroy the plant matter. Sanitize clippers with an alcohol wipe after pruning diseased plants to prevent spreading the fungi to healthy plants. It’s also important to keep the ground around plants free of decaying leaves, which act like a nursery for fungal spores.

Although you can’t do anything about humid conditions in your area, you can help plants cope with excessive moisture:

Use drip irrigationAvoid overhead wateringWater in the morningAllow enough space between plants for air circulationPrune the interior of dense plants to increase air movement