During cold, cloudy and rainy weather bedding plants can start to get backed up in the greenhouse. These are ideal conditions for Botryis to spread between plants. Univ. of Mass. floriculture extension specialist Tina Smith and Univ. of Conn. extension horticulture and greenhouse IPM specialist Leanne Pundt said growers need to monitor plants for Botrytis which can cause leaf and flower blight, cankers, damping off and root rot. The greenhouse humidity should be reduced, plants should be adequately spaced to provide good air circulation, and dropped leaves and dead flowers, which can act as an infection source, should be discarded. Smith and Pundt said some growers are hanging fish netting under flowering hanging baskets to collect spent blooms, keeping them from susceptible crops below.
Univ. of Md. extension personnel said keep plant surfaces as dry as possible. Irrigate plants early in the morning allowing any wet foliage time to dry. Operate horizontal airflow fans Operate horizontal airflow fans to increase air movement. Don’t place plants in greenhouse areas where water drips down from overhead.
Keep the greenhouse as clean as possible. Botrytis is a great survivor.
Pictured: Botrytis symptoms starting to appear on petunia leaves.
Photo courtesy of Univ. of Md. Extension