Control Methods for Tropical Orchid Petal Gray Mold and Notes on Introducing Edible Fungi

The pathogenic fungus causing petal gray mold damage is botrytis cinerea. The symptoms are small round brown spots appearing on petals and sepals. It is relatively common in Phalaenopsis, Cattleya, and Oncidium orchids, and is mainly caused by high humidity and poor ventilation. During low temperatures in winter and spring, in order to prevent outside cold air from invading the greenhouse and harming the orchids, doors and windows are often kept tightly closed or insulation measures are taken, resulting in very high relative humidity inside the greenhouse, which is exactly a good opportunity for this disease to occur and spread. This fungal disease is a widespread pathogen with as many as hundreds of host species, and can infect flowers, ornamental plants, vegetables, and fruit trees. From February to May each year, it commonly occurs in cultivation greenhouses. If Phalaenopsis flowers are infected, it not only affects their ornamental value, but also reduces their commercial value, and may even make them impossible to sell, causing great losses. The control methods are as follows:

Pay attention to ventilation and air permeability, and reduce environmental humidity.

Before the first flower opens, begin spraying 50% Prochloraz wettable powder at 2000 times dilution, and thereafter spray once every 2-4 weeks.

During the flowering period, immediately remove diseased flowers and burn or bury them in a centralized manner.

Other ornamental plants and flowers inside and outside the greenhouse also need to be sprayed at the same time for protection.