After purchasing, strawberries are quite susceptible to gray mold, caused by the fungal pathogen Botrytis cinerea. Other common fungal diseases of strawberry include powdery mildew and anthracnose. These diseases pose big problems for growers, who traditionally apply fungicides to control them. And many fungicides are not even an option for organic producers.
Fortunately, Agricultural Research Service (ARS) scientists are on the case, looking for ways to keep strawberries mold-free without fungicides.
Ultraviolet-C (UV-C) irradiation has been studied as a way of killing microbes by damaging their DNA, but at effective doses, it damages leaves and fruit. ARS scientists Wojciech Janisiewicz and Fumiomi Takeda discovered a way to sidestep this problem. They demonstrated that UV-C irradiation of strawberry plants—followed by a period of darkness—resulted in drastic kill of the Botrytis pathogen, the powdery mildew fungus, and anthracnose. In fact, the technique increased UV-C’s killing power 6- to 10-fold, depending on the pathogen, with no damage to the leaves, flowers, or fruit.