In search of new methods to control gray mold

Gray mold caused by Botrytis cinerea is a widespread disease in ornamental plant production during propagation, production and post-harvest storage that readily infects flowers, stems or leaves. A common industry problem involves Botrytis infection of bedding plant flowers during post-harvest shipping. The most common example is meltdown of petunia flowers.

Despite growers sending plants with no symptoms of gray mold to the retailer, fungal spores may have already infected flower tissues in the greenhouse and remain latent until conditions for proliferation improve. Then, the pathogen develops during shipment causing necrotic flowers when they reach the market, resulting in unsellable plants. Being a fungus that develops well in cooler climates, ornamental plants marketed during the spring are highly vulnerable to gray mold. Plants are especially susceptible to Botrytis when the foliage is wet during transport or if the relative humidity is more than 94% inside the shipping racks and trucks.

Fungicide application prior to shipment is the most common control measure in bedding plants, however efficacy is limited. Fungicide resistance is an issue. Therefore, novel control methods are required.

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