VIEW ARTICLE

Time, Temperature, and Soil Moisture Effects on Xiphinema bakeri Nematode Survival in Fallow Soil. Jack R. Sutherland, Department of the Environment, Canadian Forestry Service, Pacific Forest Research Centre, Victoria, British Columbia, Canada; L. J. Sluggett, Department of the Environment, Canadian Forestry Service, Pacific Forest Research Centre, Victoria, British Columbia, Canada. Phytopathology 64:507-513. Accepted for publication 29 October 1973. DOI: 10.1094/Phyto-64-507.

Survival of Xiphinema bakeri nematodes in soils stored at various combinations of time, temp and soil moisture tensions was studied to determine why nematodes decline in bare-fallowed, forest nursery soils. In soil stored from 1 to 32 wk at 4, 15, or 30 C at moisture tensions of pF 2.5, 3.5, or 4.2, nematode survival was significantly affected by time and moisture tension, but not by temp. X. bakeri survived best for the entire 32-wk period in soil kept at 4 C and pF 2.4; survival was poorest (only 16 wk) at 30 C and pF 4.2. Nematodes in early developmental stages were more susceptible to adverse temp and soil moisture conditions than were pre-adult and adult nematodes. In soil at pF 3.8, all X. bakeri nematodes were killed by exposure to 46 C for 15 min, and at 20 C, all nematodes were killed at pF 5.14. To determine levels at which the single or combined effect of time, temp and soil moisture tension were lethal to X. bakeri, nematode-infested soil was stored for 0 to 8 h at 36, 39 or 42 C at moisture tensions of pF 3.5, 4.2, 4.5 or 4.8. Overall, nematode survival decreased most rapidly between 0 and 4 h storage, when temp exceeded 39 C. It decreased linearly with increasing soil moisture tension. It was concluded that X. bakeri nematode longevity in hot, dry, fallow soil depends upon the combined effect of time, temp and soil moisture.