Pratylenchus penetrans (Cobb) Populations as Influenced by Microorganisms and Soil Amendments.

Numbers of Pratylenchus penetrans in sterilized soil decreased significantly 2 weeks after the addition of 1% w/w (700 ppm N) nonsterile soybean meal (SBM), or sterilized SBM in combination with selected microorganisms. Sterilized SBM had no effect on nematode populations in steamed soil. Bacteria and fungi in the presence of SBM were more effective than the actinomycetes tested, causing up to 96-100% reduction in nematode populations. Simpler nitrogenous compounds included KNO, Ca(NO), NHNO, (NH)CO, urea, and peptone, decreased nematode populations with variable effectiveness when added to steamed soil at 700 ppm N; KNO was the most nematicidal.