Botrytis Control
Botrytis cinerea, commonly known as Gray Mold, is one of the most common diseases of greenhouse crops and can occur year-round. Symptoms are gray, fuzzy coating on aging flower blossoms and soft, ripe fruits, leaf spots and bud rot. Cooler temperatures, high humidity, and water on plant surfaces are conditions that will facilitate Botrytis, 60-70º F being optimum for Botrytis growth. Many crops are susceptible to this fungus so monitoring and prevention are key.
Botrytis can overwinter or lay dormant in plant debris until a susceptible host is present. Botrytis spores are easily dislodged and carried from infected plant tissue by air currents, landing on nearby crops. The spores germinate and send hyphal tubes into the plant cells by penetrating the cell wall. These hyphae can invade flowers, fruit, leaves and succulent stems. They do not infect woody tissue. As the disease progresses, infected tissues can become waterlogged, dark, wilted, fuzzy and coated in fresh spores.
Botrytis spores will readily infect dead or declining plant tissue, so keeping crops vigorous and healthy is key to stopping this disease. Good sanitation, including removing old blossoms, decaying plant tissue, fallen leaves and weeds is critical. Proper spacing of plants will improve air circulation and, when possible, avoid overhead irrigation to keep foliage dry. Good air circulation in the greenhouse, including the use of horizontal air fans, is important to keep air currents flowing and botrytis at bay.
Many biological fungicides are labeled for Botrytis, including Guarda, Regalia, Cease, Serenade, Stargus, Milstop, Kaligreen, All Phase, Armory, Actinovate.
For more information visit UConn Extension, Botrytis Blight on Greenhouse Crops.
Tips on Mitigating Spring Botrytis, Greenhouse Grower March 2024
