Description:

Gray Mold is sometimes confused with old age and thrips damage. To help separate browning on petals caused by old age and the disease, check the petals closely. Browning from old age should occur on the outer petals first and along the edges or at the tip of the petals. When inner petals or the middle of the petals develop brown lesions first, gray mold is probably the reason. On leaves that are relatively thin such as redbud, lesions are light brown to brown and irregular. On fleshier leaves such as rhododendrons concentric rings of different shades of brown may be visible.

Damage:

Some trees and shrubs that are susceptible are alder, apple, apricot, ash, azalea, barberry, cherry, Douglas fir, flowering almond, hawthorn, holy, honeysuckle, hydrangea, larch, lilac, magnolia, mockorange, peach, pear, persimmon, plum, rhododendron, and viburnum.

Some vegetables and small fruit plants that are susceptible to gray mold include artichoke, asparagus, bean, beet, blackbery, black-eyed pea, blackberry, blueberry, broccoli, Brussels sprouts, cabbage, carrot, cauliflower, celery, chives, cucumber, currant, eggplant, endive, gooseberry, grape, kale, kohlrabi, leek, lentil, lettuce, okra, onion, parsnip, pea, peanut, pepper, pumpkin, quince, raspberrie, rhubarb, rutabaga, shallot, squashe, strawberry, sunflower, sweet potato, tomato, and turnip.

Control:

The disease often over-winters on infected dead plant material. Sanitation is important. Dead head dying flowers and remove all infected plant tissue. Burning is the desired method of destroying infected tissue. If burning is a problem then infected plant material may be buried. Dig a hole at least a foot deep. Cover the infected Botrytis plant material with at least a foot of soil.

Please check the "Extension Agents' Handbook of Insects, Plant Disease and Weed Control".