Damage and Reproductive Potentials of Pratylenchus brachyurus and P. penetrans on soybean

Damage and reproductive potentials of Pratylenchus brachyurus and P. penetrans on soybean, Glycine max, cvs. Essex, Forrest, and Lee 68, were determined in microplot tests. Cultivar Essex was generally tolerant to P. brachyurus. Yield of Forrest was suppressed linearly with increasing P(i)'s in the sandy soil (r = -0.92) and loamy sand soil (r = -0.99). Low to moderate P(i)'s in the sandy clay loam gave an increase in yields as compared to plants without nematodes. Yield was not affected by this nematode in muck. Lee 68 was very sensitive to P. penetrans in microplots. Yield vs. P(i) was fitted by a quadratic model (r = 0.82) with yield decreasing sharply as P(i)'s were increased. The reproduction of both species decreased with increases in P(i). Lee 68 was a good host for P. penetrans, whereas Essex and Forrest were fair to poor hosts for P. brachyurus.