ASHS 2024 Conference

Anthracnose fruit rot (AFR) caused by Colletotrichum acutatum is a major strawberry pathogen in the U.S. affecting both perennial and annual systems. This pathogen can survive in the soil rhizosphere from the previous seasons. Anaerobic soil disinfestation (ASD), an alternative to chemical fumigation methods, has been shown to effectively suppress a wide range of soilborne pests. Beneficial bacteria, such as Bacillus spp., are important biocontrol agents due to their capacity to reduce the growth of pathogens while also promoting plant growth. We proposed that ASD, beneficial bacteria, and their combinations could reduce fruit rot diseases of strawberries and improve crop yield and fruit quality parameters. A trial was conducted using a split-plot design with four replicates at the Hampton Roads AREC, Virginia Beach, VA. ‘Chandler’ strawberry plug plants were planted in various treatments as stated below: non-disinfested field plots (Control); field plots treated with Pic-Clor60 at 196 kg/ha (preplant soil fumigant) (Pic); field plots treated with ASD alone. Additionally, strawberry plants in each of these main treatments were treated with one of the following sub-treatments: no beneficial bacteria (untreated control), Bacillus velezensis only; TerraGrow (a mixture of five Bacillus spp.) at 1.7 kg/ha only; and TerraGrow 1.7 kg/ha applied 4 hours post Oxidate 5.0 (27% hydrogen peroxide, 5% acetic acid and 5% peroxyacetic acid) at 23,385 L/ha. Fruits were harvested twice per week starting 5 April through 20 June, 2023. Harvested fruits in each replicate or sub-plot were sorted into marketable and non-marketable categories. Non-marketable fruits included diseased fruits, small fruits or deformed fruits. Fruit weights were summed for the season by replicate and expressed as g/plant. Fruit firmness and total soluble solids (TSS) were measured on five representative marketable fruits per replicate once per harvest week and data were averaged for the season. For AFR, the weight of diseased fruits decreased significantly in sub-plots treated with B. velezensis, TerraGrow, and TerraGrow post Oxidate compared with the untreated control. In general, the ASD treatment significantly decreased the weight of AFR diseased fruits compared to the control and Pic-Clor 60 fumigation treatments. Fruit from ASD treated plots showed increased firmness and higher Total Soluble Solids values compared to Pic-Clor 60 plots. However, the marketable and total yield was lower in the ASD plots compared with other treatments. Our findings indicate that the utilization of beneficial microorganisms with ASD has the potential to reduce fungal diseases in annual hill strawberry production system.