Until now, blossom blight of strawberries in California has been mostly attributed to the fungus Botrytis cinerea. However, UC scientists have discovered that more than one organism is responsible. Their investigation has revealed that a new fungus and the bacterium Xanthomonas fragariae alsocause the disease.
In the July-August issue of California Agriculture, UC Davis plant pathologist Doug Gubler and colleagues describe for the first time how the bacterium and the fungus Cladosporium cladosporioides cause blossom blight in strawberries.
Plants infected with blossom blight produce small or misshapen strawberries. In a study of infected strawberry fields in Watsonville, the scientists found that infection by the bacterium seemed to aggravate the effect of the fungus, and vice versa, but each organism was capable of causing blossom blight independently. Blossoms infected with these organisms developed symptoms distinct from each other. X. fragariae can cause occasional fruit loss, but this is considered of minor economic importance in California strawberry production fields. More significant is C. cladosporioides, which renders the fruit unattractive and therefore reduces the market value of the crop.
California grows approximately 80% of the 1,500 million to 1,600 million pounds of strawberries produced each year in the United States. Of the strawberries grown in California, more than 50% comes from the Central Coast, specifically the Salinas and Watsonville areas.
Journal
California Agriculture