Sclerotinia - an underestimated greenhouse disease

Sclerotinia sclerotiorum, better known as white mold or cottony mold, is not talked about as a serious greenhouse disease. However, it can cause root rot, stem rot, blighting of foliage and leaf petioles in a wide variety of greenhouse crops, including alyssum, begonia, gazania, geranium, gerbera, gloxinia, larkspur, lobelia, petunia, stocks, vinca and zinnia.

It is more commonly found in field crops such as cabbage, carrot, clover, common bean, celery, cilantro, citrus, cucumber, eggplant, lettuce, various melons, peanut, pepper, potato, soybean, squash and tomato, where high humidity and rain can exacerbate the disease. It is not known to attack grasses.

The first visible symptoms of Sclerotinia include light brown lesions that form on stems, leaves or flowers. These spots appear as water-soaked, but in some plant species it appears as a dry rot. As it progresses, plant tissue is quickly destroyed, often with a narrow transition from tan, diseased tissue to normal tissue. If infection occurs in the stem or crown of a plant, a lesion can girdle the stem, causing wilting of the leaves, which can turn yellow and then brown. Eventually, the whole stem dies. If canopies are dense and humidity is high, the disease can quickly spread throughout a single plant and transfer from one plant to another.

Read more at PRO-MIX (Troy Buechel)