Anthracnose fruit rot (AFR) of strawberry is caused by three Colletotrichum spp. In the Midwest, however, only Colletotrichum acutatum is found. This fungus can attach itself to apparently healthy plants and spread throughout the field without causing symptoms on the foliage. When fruit begins to ripen and weather conditions are rainy and warm, AFR can suddenly cause great damage to the fruit. To protect against AFR where it has appeared in the past, growers need to spray every 7 to 10 days beginning at the start of bloom until harvest.
Zhang, Xiaoyu; Batzer, Jean C.; and Gleason, Mark L., "Testing a Warning System for Anthracnose Fruit Rot on Day-neutral Strawberry—Year 3" (2014). Iowa State Research Farm Progress Reports. 1999.