Managing Meloidogyne chitwoodi on Potato with Rapeseed as Green Manure. H. Mojtahedi, Research Associate, Departments of Plant Pathology and Crop and Soil Sciences, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350-9687. G. S. Santo, J. H. Wilson, and A. N. Hang. Professor and Nematologist, Agriculture Research Technologist III, and Associate Agronomist, Departments of Plant Pathology and Crop and Soil Sciences, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350-9687. Plant Dis. 77:42-46. Accepted for publication 12 September 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0042.

Leaves of the rapeseed (Brassica napus) cultivar Jupiter used as a soil amendment effectively reduced Meloidogyne chitwoodi population densities at the zone of incorporation. Soil in the zone of incorporation was protected from nematode colonization for 6 wk. Stem and root tissues of rapeseed were also effective when homogenized before being used as an amendment. Greenhouse-grown plants accumulated more glucosinolates and became more effective in suppressing M. chitwoodi with age. Second-stage juveniles were more sensitive than egg masses, with ED₅₀ of 10 and 23 mg of green leaves of 4-mo-old rapeseed per gram of soil, respectively. For two consecutive years, planting Jupiter rapeseed in the fall and incorporating it in the spring as green manure limited M. chitwoodi damage on potato (Solanum tuberosum) tubers in field experiments. Augmenting green manure amendment with ethoprop further reduced nematode damage to potato tubers and resulted in commercially acceptable tubers similar to those obtained from plots treated with 1,3-dichloropropene.

Keyword(s): Columbia root-knot nematode, organic amendment.