How to prevent and control bud blight in hydrangea

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

Symptoms: In plants grown in the open field, it readily occurs on dense spherical flower clusters, causing them to develop water-soaked rot. In greenhouse cultivation, buds readily turn black and wither.

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

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

Prevention and 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.