Great info below on botrytis flower blight — especially the photos. Be sure to take a look at the link mentioned at the bottom — smallfruits.org
Botrytis flower blight and fruit rot caused by the fungus Botrytis cinerea is likely to be a problem this year in NC. The disease can become severe when freeze injury to flowers is followed by cool, wet weather. Over the past month we have seen repeated freeze damage to emerging blooms so the risk of flower blight is already high due to the amount of injured tissue. The fungus infects through damaged flowers, may kill the entire fruiting twig, and can also cause a fruit rot at harvest.
|Freeze-injured flowers are predisposed to flower blight|
|Masses of spores are visible on the infected flower bud at center|
|Post-harvest Botrytis fruit rot|
The best control measure for this disease on blueberry is warm, dry weather! With dry, sunny days any freeze-damaged flowers will quickly dry out and fall off. However if cool wet weather is anticipated, the use of a fungicide may be warranted, and there are a number of labeled fungicides for control of this disease. If you are already spraying fungicides for mummy berry, this might be a good year to include a product that has activity against flower blight. Recommended products can be found at smallfruits.org in theBlueberry IPM Guide. Page 31 lists the relative effectiveness of fungicides against this disease. Some good choices would be CaptEvate, Elevate, Pristine or Switch. As always, read and follow the label.