Effects of Temperature on Pratylenchus neglectus and on Its Pathogenicity to Barley

In a petri-dish study, development of the nematode Pratylenchus neglectus was observed every 4 days, and stage-specific development times were estimated, using a parameter estimation algorithm for a distributed-delay population model. The lower threshold temperature for development of a population of P. neglectus was 7.75 C. Temperatures above 25 C were unfavorable for this population on barley. Total numbers of P. neglectus in barley roots and associated soil in pots were greatest at 25 C and lower at temperatures above and below that level. There was no change in nematode numbers per gram of root as temperature increased between 24 C and 32 C because root weights decreased at higher temperatures. Restricted root mass may contribute to the lower total nematode population levels at higher temperature. Maximum number of nematodes moved through a 2-cm layer of sand on a Baermann funnel at about 20 C; lowest number of nematodes moved at 10 C and 30 C.