Effect of Low Temperatures in the Field and Laboratory on Survival of Pratylenchus penetrans. J. Kimpinski, Nematologist, Agriculture Canada Research Station, P.O. Box 1210, Charlottetown, Prince Edward Island C1A 7M8. R. A. Dunn, Extension Nematologist, Florida Cooperative Extension Service, University of Florida, Gainesville 32611. Plant Dis. 69:526-527. Accepted for publication 19 December 1984. Copyright 1985 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-69-526.

Effects of winter temperatures on the survival of Pratylenchus penetrans in annual ryegrass and orchard grass in upper New York State and in red clover on Prince Edward Island were investigated. The numbers of nematodes in soil depths of 0–15 cm decreased 35–59% from December to April during 4 yr when the average soil temperatures were –1.1 to –0.8 C. Nematode numbers increased 39% during one winter on Prince Edward Island when the soil temperatures ranged from 0.1 to 0.4 C. Nematode mortality in laboratory studies at both –12 and –8 C was about 93% after 4 hr of exposure. The duration of exposure needed to kill 50% of the population at –4, 0, and 4 C was 3.4, 124, and 742 days, respectively. These data may be a useful guide for predicting the size of spring populations of P. penetrans from samples collected in the fall or winter.