Symptom Identification and Control Methods for Hydrangea Bud Blight

Hydrangea bud blight is also known as hydrangea gray mold. It damages the buds and flowers of the plant.

Symptoms: In field-grown plants, it easily occurs in dense spherical flower clusters, causing them to develop water-soaked rot. In greenhouse cultivation, buds are prone to turning black and withering.

Pathogen: The pathogen is Botrytis cinerea Pers., belonging to the Deuteromycotina, Hyphomycetes, Moniliales, genus Botrytis.

Disease pattern: The pathogen overwinters as mycelium in diseased plant debris. In the following spring, it produces conidia, which are spread by wind and rain to infect plants. During the growing season, conidia can repeatedly infect the host. Under warm and humid conditions, the disease occurs severely.

Control: (1) Reduce sources of infection: Thoroughly remove diseased plant debris and destroy it in a centralized manner. (2) Chemical control: In the early stage of the disease, spray 70% thiophanate wettable powder at 1000 times dilution, or 50% benomyl at 800-1000 times dilution, once every 10-15 days, spraying 2-3 times. During greenhouse storage, spray 50% carbendazim wettable powder at 800-1000 times dilution, or 50% benomyl at 1000 times dilution for control.