COMPARISON OF ANAEROBIC SOIL DISINFESTATION AND DRIP-APPLIED ORGANIC ACIDS FOR RAISED-BED SPECIALTY CROP PRODUCTION IN FLORIDA

Anaerobic soil disinfestation (ASD, aka biological soil disinfestation) has been studied in multiple countries for the suppression of plant pathogenic fungi and bacteria. Recent work in the US has included studies on weed control and nematode management with this technique. Multiple mechanisms have been shown to play a role in the suppression of some studied plant pathogens, including the generation of organic acids by soil bacteria. Multiple field trials were conducted in the strawberry production region in Florida to compare this method with direct application of a novel combination of organic acids (referred to as ‘SPK’) applied through drip irrigation. Application of the organic acids consistently resulted in an increase in the native soil population of Trichoderma spp. The first year of ASD treatment resulted in a low level of cumulative redox potential and an increase in Trichoderma spp. However, in the second year, when there was a higher level of cumulative redox potential, an increase in culturable soil bacteria overwhelmed Trichoderma spp. colony isolation. Viability of introduced fungal plant pathogen inoculum was reduced in organic acid treatments when the water front carrying the acid came in direct contact with packets at the center of the bed, but not in areas with poor material movement. Introduced inoculum in the ASD-treated plots was significantly reduced compared to the untreated control regardless of packet placement.