Relation ofMeloidogyne haplaandMacroposthonia ornataPopulations to Cylindrocladium Black Rot in Peanuts

Diomande, M., and Beute, M. K. 1981. Relation of Meloidogyne haplu and Mucroposthonig ornata populations to Cylindrocladium black rot in peanuts. Plant Disease 65:339-342. Five field experiments were established in Cylindrocludiuni crotaluriue-infested peanut fields from 1976 to 1978. Populations of Macroposthoniu ornata, Meloidogyne hapla, and Cylindrocladium crorulariue 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. ornutu and the disease were either less pronounced than those with M. hapla or not significant. Final populations of M. ornata were consistentlygreater on NC 3033 than on Florigiant. In microplot tests, C. crotaluriue combined with M. ornatu caused more disease on Florigiant but not on NC 3033 than did C. crotuluriae 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.