Research Papers: Relation of Fertilizer Treatments and Cropping Sequence to Populations of Two Plant Parasitic Nematode Species

Abstract

Soil populations of Helicotylenchus dihystera (Cobb) Sher and Trichodorus christiei Allen in a continuing three-year rotation scheme were found to vary with season. The rotation scheme consisted of summer crops of corn, soybean, and cotton. These were followed, respectively, by winter programs of wheat, fallow, and mixed common vetch and crimson clover. The rotation was superimposed on plots that received various combinations of N,P,K, minor elements and lime. Our results show that populations of H. dihystera and T. christiei are influenced by fertilization regime of the soil. Effects on the size of the population do not appear to be related to the absence of any one nutritional element, but rather to whether an essential major element is present or absent in the fertilization scheme regardless of its identity. Nutrient deficiencies resulted in virtual elimination of H. dihystera from plots, and reduced the size of populations of T. christiei. Lack of lime resulted in significant inc