Pathogenicity of Pratylenchus penetrans to Navy Bean (Phaseolus vulgaris L.)

The pathogenicity of Pratylenchus penetrans (root-lesion nematode) to Phaseolus vulgaris (navy bean) was evaluated in greenhouse experiments. Shoot and root fresh weight of cv. Sanilac plants were increased 4 and 21%, respectively, by an initial population density (Pi) of 25 P. penetrans per 100 cm(3) soil. Leaf area and shoot fresh and dry weights were decreased by a Pi of 50 or more P. penetrans per 100 cm(3) soil. A significant positive linear relationship existed between initial soil population densities of P. penetrans and final soil and root population densities of this nematode. Three dry bean cultivars, Sanilac, Seafarer, and Tuscola, were susceptible to P. penetrans, and yields were reduced by 43-76% when plants were exposed to a Pi of 150 P. penetrans per 100 cm(3) soil. P. penetrans also reproduced on bean cultivars Saginaw, Gratiot, and Kentwood, but did not decrease bean yields, suggesting that these cultivars were tolerant to this nematode.