Non-chemical approach to soilborne pest management - organic amendments

Chemical soil disinfestation often leads to the eradication of most microbi al residents. This creates a microbial vacuum, which often leads to a rebou nding of pathogens. This in turn may cause even more damage than those orig inally targeted for control. Soils, especially those with low microbial pop ulations are more vulnerable to pathogen reinvasion following fumigation. A non-chemical approach to improve the control of soilborne pests involves c ombining organic amendments with soil solarization. Heating soils, that hav e been covered with plastic film and amended with suitable organic material s, actuates a chain reaction of chemical and microbial degradation, which l eads 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 mul ch traps the volatile compounds and creates an atmosphere in the soil that enhances degradation of the organic matter. The toxicity of the generated v olatile compounds is expected to be higher at the high soil temperature pre vailing during solarization. At the end of the process, the soil contains l ess pathogens, and different microflora, which may suppress reestablishment of pathogens in the soil. The effect of solarizing organically amended soi l as a control method was validated under commercial field conditions. A lo ng-term effect of the combined treatments was also evident. (C) 2000 Elsevi er Science Ltd. All rights reserved.