Evaluation of Southern Stem Blight Control in Green Beans with Aerated Compost Tea in Drip System

View the project final report

Commodities

Practices

• Crop Production: biological inoculants, fertigation
• Pest Management: biological control, compost extracts
• Production Systems: organic agriculture
• Soil Management: soil microbiology, soil quality/health

Southern stem blight is a fungus present in many soils across the Southeast. This fungus is responsible for the loss of many valuable vegetable crops including tomatoes, peppers, and beans. The effects of this blight occur during summer where temperatures are between 77-92 degrees. On our farm, losses are often so rapid that any action taken is too late. With crop loss comes loss of income, which is something any farmer wants to minimize as much as possible.

Many organic farmers use compost as a soil building block on the farm. On our farm we work hard on our compost creation, treating it like we would a crop. We use the compost on our farm as a way to increase sustainability, build up carbon in the soil, develop the soil’s moisture holding capacity, as a mild fertilizer, and to inoculate our fields with beneficial microbes. To maximize this resource the compost is also brewed into a tea. We create the compost tea through an aerated process with a purchased compost tea brewing machine that constantly circulates oxygen with an air pump. The aerated compost tea can be used as a foliar spray or run through our drip irrigation. Our research focuses on testing the efficacy of using compost tea as a competitive biostimulant to increase the beneficial microbial activity, which could suppress the negative activity of Southern stem blight. We believe that creating a significant competition for access to the rhizosphere of our plants will slow, and potentially inhibit, the quick spread of Southern stem blight.  Research from Bulluck et al. in Organic and Synthetic Fertility Amendments (2002) and Liu et al. in Long Term Effects of Organic and Synthetic Soil (1997) has suggested that organic amendments such as compost and organic inputs, and the presence of soil microbes, such as Trichoderma spp., Bacillus subtilis, and Pencillium spp., can help suppress the infection and spread of Southern stem blight.