Exposure time to lethal temperatures for Meloidogyne incognita suppression and its implication for soil solarization

摘要

Meloidogyne incognita eggs or J2 were incubated in test tubes containing sand:peat immersed ill a water bath heated to 38, 39, 40, 41, 42, 43, 44 and 45 degrees C for a series of time intervals. Controls were maintained at 22 degrees C. Nematodes surviving or hatching were Collected from Baermann trays after three weeks Of incubation. Regression analyses between percent survival or egg hatch and hours Of heat treatment were performed for each temperature. Complete Suppression of egg hatch required 389.8, 164.5, 32.9. 19.7 and 13.1 hours at 38, 39, 40, 41 and 42 degrees C, respectively. Complete killing of J2 required 47.9, 46.2, 17.5 and 13.8 hours at 39, 40, 41 and 42 degrees C, respectively. J2 were not completely killed at within 40 hours of treatment, but were killed within one hour at 441 and 45 degrees C. Effect of temperature oil nematode killing is not determined by heat units. Oscillating temperature between cool and warm fill not interfere with the nematode Suppressive effect by the heat. treatment. Six-week solarization ill the field during the summers of 2003 and 2004 ill Florida accumulated heat exposure times in the top 15 cm of soil surpassed levels required to kill M. incognita as determined ill the water bath experiments. Although near Zero M. incognita were detected right after Solarization, the nematode population densities increased after a cycle of a susceptible pepper crop. Therefore, future research should address failure of solarization to kill nematodes in the deeper soil layers.