Gray sporulation of Botrytis cinerea.
If there is a late freeze or even cold weather during bloom time, check the flowers and young fruit for the presence of Botrytis blight. If Botrytis is present, there will be a gray-green fuzzy growth on the plant tissues. Botrytis will usually cause losses early in the growing season, but a lot of rainy weather during the spring may also lead to Botrytis problems. It is not recommended to treat preventatively for this disease. Treat only if there is a frost that damages blooms or if there has been a significant cold spell.
There are two options for good Botrytis blight control. One is to use a fungicide with the active ingredient fenhexamid and is in the chemistry group hydroxyanilides (FRAC code 17). Another option is to use a fungicide in the multi-site mode of action chemistry group (FRAC code M). This fungicide will be most effective if applied as a preventative spray.
Consult your local Cooperative Extension Service office for current fungicide recommendations. Information also can be found in the Southeast Regional Blueberry Integrated Management Guide.
Contact:
Bill Cline, North Carolina State University Cooperative Extension Service.
Related article:
Harmon, Philip F. Botrytis Blossom Blight of Southern Highbush Blueberry. University of Florida. IFAS Extension.