Anthracnose fruit rot (AFR) of strawberry is considered to be caused by three Colletotrichum spp. In the Midwest, however, only Colletotrichum acutatum is found. This pathogen can attach itself to 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 large sunken lesions on the fruit. To protect against AFR where it has occurred in the past, growers need to spray every 7 to 10 days beginning at the start of bloom until harvest.
Iowa State University
Zhang, Xiaoyu; Batzer, Jean; and Gleason, Mark, "Testing a Warning System for Anthracnose Fruit Rot on Day-neutral Strawberry–Year 4" (2015). Iowa State Research Farm Progress Reports. 2161.