Nematode response to methyl bromide and 1,3-dichloropropene soil fumigation at different temperatures

Several heat-based methods, such as soil solarization, are being developed as alternative practices for managing soil-borne pests and pathogens. The e ffectiveness of these practices is often inconsistent or marginal, thus com manding the need for their integration with other methods. The main objecti ve of this study was to determine synergistic interaction between soil fumi gants and temperature. Soil infested with citrus nematode Tylenchulus semip enetrans was exposed to methyl bromide or 1,3-dichloropropene at various te mperatures. Fumigant degradation was concurrently measured and concentratio n-time index let) was calculated and correlated to the recovered nematode p opulation. In untreated soil, nematode survival was not affected by tempera tures of 20-30 degrees C, but was strongly reduced at greater than or equal to 40 degrees C. In fumigated soil, nematode suppression was much greater at 30 degrees C than at 20 degrees C, and the ct required for nematode elim ination at 30 degrees C was < 50% of that needed at 20 degrees C for both f umigants. These results suggest that these fumigants became more active wit h increasing temperature in the sub-lethal temperature range. It also impli es that, when integrated with a heat-based practice, reduced rates of fumig ants may provide adequate pest control, thus minimizing the environmental i nput of chemical fumigants. (C) 2000 Society of Chemical Industry.