Relation of Meloidogyne hapla and Macroposthonia ornata Populations to Cylindrocladium Black Rot in Peanuts. Mamadou Diomande, Graduate Research Assistant, Department of Plant Pathology, North Carolina Agricultural Research Service, Raleigh 27650. M. K. Beute, Professor, Department of Plant Pathology, North Carolina Agricultural Research Service, Raleigh 27650. Plant Dis. 65:339-342. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-339.

Five field experiments were established in Cylindrocladium crotalariae-infested peanut fields from 1976 to 1978. Populations of Macroposthonia ornata, Meloidogyne hapla, and Cylindrocladium crotalariae microsclerotia were determined in each field three times during each growing season. Correlations between populations of these organisms and the severity of Cylindrocladium black rot (CBR) were analyzed using multiple regression models. In all tests, CBR-resistant cultivar NC 3033 sustained less disease than CBR-susceptible Florigiant and final populations of microsclerotia were higher on Florigiant than on NC 3033. Correlations and the partial correlations of M. hapla and C. crotalariae populations with CBR severity were generally significantly positive on both cultivars. Correlations between M. ornata and the disease were either less pronounced than those with M. hapla or not significant. Final populations of M. ornata were consistently greater on NC 3033 than on Florigiant. In microplot tests, C. crotalariae combined with M. ornata caused more disease on Florigiant but not on NC 3033 than did C. crotalariae in the absence of M. ornata. Reproduction factor (ie, final population/initial population) for M. ornata, however, was higher on NC 3033 than on Florigiant.

Keyword(s): Arachis hypogaea, disease interaction, ring nematode, root knot nematode.