In addition to frost protection, disease management is pivotal during the blooming stage, particularly concerning gray mold (caused by Botrytis spp.) and Anthracnose. To protect the fruit, fungicide application should commence at or even before blooming. The pressure of both diseases is heavily influenced by weather conditions, with Botrytis favoring wet and cool climates and Anthracnose thriving in wet and warm conditions. While Botrytis is widespread, plasticulture generally experiences lower Botrytis pressure compared to matted row systems. Conversely, the primary source of anthracnose infection is likely from asymptomatic planting materials, and the disease could be more severe in plasticulture than in matted row systems. Dry weather during blooming and harvest stages may mitigate disease risks. However, in the event of a wet spring, timely fungicide application becomes imperative to disease management.
How often should apply fungicide? The best way to decide fungicide application frequency is through a weather-based forecasting tool. The Network for Environment and Weather Applications (NEWA) offers infection risk levels for Botrytis and Anthracnose and gives recommendations for application frequency. The system has three weather stations currently operational in Indiana—Romney, Converse, and New Castle. Growers in nearby areas can leverage this tool to guide fungicide applications. A weather station is not yet available in southern Indiana. Please let me know if you are interested in setting up one at Southwest Purdue Agriculture Center (SWPAC). Growers may also consider investing in one for their farm.
As a general guideline, one to three fungicide applications during bloom can provide sufficient control for Botrytis. Additional fungicide spraying post-bloom may not yield additional control against Botrytis and might lead to fungicide resistance. Hence, utilizing multisite fungicides and rotating between groups is imperative whenever feasible.
For specific fungicide recommendations, please consult the Midwest Fruit Pest Management Guide. Dr. Janna Beckerman had fungicide recommendations for each strawberry growth stage in the production guide.
For additional information about strawberry diseases and disease management considerations during the spring, please refer to the Strawberry Chat podcast Spring Diseases and Management Episode 9. March 9, 2023