BIOLOGY AND MANAGEMENT OF CHARCOAL ROT OF MUNGBEAN (Vigna radiata L.) Wilczek AND MASHBEAN (Vigna mungo L.) Hepper

Abstract

Charcoal rot, incited by Macrophomina phaseolina (Tassi) Goid, is a serious disease of many crops, inflicting 100 % yield losses in Mung and Mash bean under dry and hot conditions. Therefore, biology and management of the disease was studied in 65 isolates of the fungus collected from 14 districts of Punjab and Khyber Pukhtoon Khwa. Morphologically, the isolates differed significantly in their growth behaviour, sclerotial size and weight. Sixteen isolates developed fast growth, 11 were slow and the rest were intermediate. Nine isolates produced large sized sclerotia, 26 small sized while the left over were intermediate. Similarly 35 isolates produced high weight of sclerotia, 12 low and the rest were intermediate in weight. Isolates collected form D.G.Khan, Chakwal and Bhakar were found to be highly variable. All the isolates differed in variability in aggressiveness. On the basis of infection, 23 isolates appeared to be highly virulent, 5 were least virulent and the remaining isolates showed intermediate response. Biological agents, antagonistic plant materials and chemicals were tested against the disease. All the test antagonists inhibited the growth of M. phaseolina significantly, maximum of 79.63 % with T. harzianum and minimum of 58.14 % with T. pseudokoningii over control. Antagonists also affected survival of mung and mashbean plants significantly which was significantly higher at higher concentrations of all the antagonists. Survival of mung and mash plants treated with T. harzianum @ 2 x 10 8 was found maximum (83.33 and 80.0%) and minimum in case of T. pseudokoningii. Similarly, all the test plants inhibited the growth of M. phaseolina significantly, maximum in case of Carum lopticum (68.61%) and2 Azadirachta indica (55.68%) the minimum (15.96%) inhibition with Nerium indicum at 100% concentration. Percentage inhibition was significantly higher at higher concentrations of all the plants as compared to other concentrations. Survival of plants was also found to be maximum, where seeds were treated with C. lopticum (83.33 and 76.66%) and A. indica (80.0 and 73.33%) at 100 % concentration. Mentha piperita and Foeniculum vulgare showed minimum plant survival (40 %) of mung and mash respectively. All fungicides inhibited the growth of M. phaseolina significantly. Maximum efficacy was shown by Benomyl (83.89%) and Carbendazim (79.11%) while Copperoxychloride showed the minimum (23.57 %). The mung and mashbean germplasm varied greatly in reaction to charcoal rot under inoculated conditions. In glass house studies, 14 out of 100 mungbean accessions appeared to be highly resistant as against 34 accessions under field conditions. In case of Mash only 5 lines out of 100 accessions were found to be highly resistant in pot experiment as against 12 accessions in the field.