摘要：

The penetration of corn roots by Pratylenchus penetrans and P. minyus in three Ontario soils under different physical conditions was tested. The optimum temperature for penetration of corn roots was 20°C for P. penetrans and 30° for P. minyus. Penetration by the two nematodes occurred over a range of moisture tensions from 0 to 1000 cm of H2O but it peaked between 10 and 100 cm H2O. Low bulk densities generally favoured nematode penetration of the roots in all soils. Penetration of corn roots was greater in Fox sandy loam, a coarse-textured soil, than in Vineland silt loam and Jeddo loam, both fine textured soils. Penetration of the roots by adults of P. penetrans was greater than by larvae in all soils; penetration of the roots by adults of P. minyus was greater than by larvae in Fox, but penetration by larvae equalled or surpassed that by adults in Vineland and Jeddo, respectively.

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