Evaluation of Anaerobic Soil Disinfestation as An Alternative to Methyl Bromide Fumigation in a Florida Bell Pepper-Eggplant Double Crop System.

Anaerobic soil disinfestation (ASD) combines brief periods of soil saturation with soil solarization, allowing reducing conditions to develop in concert with increased soil temperatures.  This technology has recently been investigated as an alternative to chemical soil fumigation for control of soilborne pathogens, plant-pathogenic nematodes, and weeds in response to the global phaseout of methyl bromide (MeBr), and as an option for organic and transitional growers.  A complete factorial field experiment with three levels of initial irrigation (10, 5, 0 cm), two levels of poultry litter (amended, unamended), and two levels of molasses (amended, unamended), in combination with solarization was established to optimize ASD for Florida vegetable production.  Untreated (UTC) and MeBr controls were included.  As indicated by redox potential (Eh), strong to moderate anaerobic conditions (-300 to 200 mV) developed in treatments amended with poultry litter and/or molasses.  Because anaerobic conditions are considered essential for pathogen control, soil amendment is necessary for ASD applications in coarse-textured, low organic matter soils typical to Florida vegetable production.  There was no significant impact of the level of applied irrigation on Eh, likely due to heavy rains occurring soon after experiment establishment.  Nutrient availability and pH were greatly affected by ASD treatment, and must be considered when adapting ASD technology.  Weed biomass from plant holes at bell pepper (Capsicum annuum) harvest was equivalent to MeBr in all treatments with soil amendments, regardless of initial irrigation.  Control of yellow nutsedge (Cyperus esculentus) emerging through plastic was inconsistent for each factorial treatment, though generally intermediate between MeBr and UTC.  Yields of marketable peppers were greater than UTC and equal to harvest from MeBr for all but three treatments.  Although more research is needed to determine optimal soil amendments (including cover crops), irrigation, and tarps for soil disinfestation, ASD is a promising alternative to chemical soil fumigation.