Effects of soil management on numbers of the root-lesion nematode Pratylenchus penetrans in soils of Ontario peach orchards

The use of herbicides and cover crops in peach orchards influenced the numbers of the root-lesion nematode, Pratylenchus penetrans, in Fox sandy loam soils. Plots treated over the entire area with the herbicide combination of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) had the smallest number of P. penetrans in the soil. The soil management practice used by many Ontario growers, clean cultivation until 1 July followed by a weed cover, resulted in the largest numbers of nematodes in the soil. Creeping red fescue (Festuca rubra L.) as a cover crop retarded the rate of increase of P. penetrans numbers in the soil but Sudan grass (Sorghum vulgare cult sudanense Hitchc.) did not. Weed control practices that permitted a temporary re-establishment of weed covers, did not retard the increase of P. penetrans numbers. Use of paraquat plus linuron to limit weed growth in the tree rows coupled with a permanent cover of creeping red fescue between the rows appears to be an effective way of retarding increases of P. penetrans numbers in peach orchards. Soil management systems that incorporate these features may be of practical value to Ontario peach growers.