Gray mold, caused by Botrytis cinerea, is the most common disease of strawberries. Managing this disease can be challenging if rainfall occurs during flowering. This year has been relatively dry, so hopefully there will be less disease pressure. Nevertheless, growers should consider fungicide applications to prevent gray mold infections. Timing of applications is critical. Botrytis is an opportunist. It infects during bloom, invading dying flower parts as bloom subsides. The fungus remains latent in the dead flower parts until the fruit begins to ripen, then grows rapidly and causes fruit rot. Fungicides should be applied at 10% bloom, then again at full bloom. Applications as fruit are ripening and rot starts to show up are ineffective.
There are several fungicides effective against Botrytis. General protectants such as Captan are reasonably effective. However, there are some fungicides specific for this pathogen. Elevate, Rovral, Scala, and Switch are specific “botryosides”, that are effective only on Botrytis. Several newer products are effective against Botrytis and other pathogens. Flint Extra, Fontelis, Kenja, Luna Privilege, etc. The 2018 Midwest Fruit Pest Management Guide lists several new options for disease management. It can be found on line at: https://ag.purdue.edu/hla/Hort/Pages/sfg_sprayguide.aspx