Non-chemical approach to soilborne pest management - organic amendments

Chemical soil disinfestation often leads to the eradication of most microbial residents. This creates a microbial vacuum, which often leads to a rebounding of pathogens. This in turn may cause even more damage than those originally targeted for control. Soils, especially those with low microbial populations are more vulnerable to pathogen reinvasion following fumigation. A non-chemical approach to improve the control of soilborne pests involves combining organic amendments with soil solarization. Heating soils, that have been covered with plastic film and amended with suitable organic materials, actuates a chain reaction of chemical and microbial degradation, which leads to the generation of toxic compounds in vapor and liquid phases in the soil. The generation of toxic compounds increases with temperature. These compounds accumulate under the plastic mulch, and enhance toxicity against soil flora and fauna, especially soilborne plant pathogens. The plastic mulch traps the volatile compounds and creates an atmosphere in the soil that enhances degradation of the organic matter. The toxicity of the generated volatile compounds is expected to be higher at the high soil temperature prevailing during solarization. At the end of the process, the soil contains less pathogens, and different microflora, which may suppress reestablishment of pathogens in the soil. The effect of solarizing organically amended soil as a control method was validated under commercial field conditions. A long-term effect of the combined treatments was also evident. (C) 2000 Elsevier Science Ltd. All rights reserved.