Efficacy of Carbendazim and other Fungicides on the Development of Resistance during Passage in Alternaria Alternata Causing Root Rot to Fenugreek

A Survey of Pathogens infecting Fenugreek (Trigonella foenum graecum. L. ), by Alternaria alternata (Fr. ) Keissler, causing root rot disease, from 12 different localities of Maharashtra was carried out. Fenugreek infected by Alternaria was observed as severe, in all pathogens. The MIC of carbendazim among 12 isolates of Alternaria alternata on agar plates (in vitro) and root rot of fenugreek (in vivo) exhibit variation i. e. from 5000 to 2500 g/ml while 500 to 1000 g/ml respectively. In vitro and in vivo culturing of sensitive isolate of Alternaria alternata (Aa-2) on carbendazim, continuously for eight successive passages showed significantly increased resistance. Use of carbendazim alternately with Aliette, Roko, Curzate, Dithane M-45 and Ridomil for eight successive passages significantly decreased resistance at 3rd passage. Use of carbendazim in mixture with Aliette, Roko, Dithane M-45, Curzate and Ridomil reduced resistance on agar plates at 2nd passage only while Curzate in mixture with carbendazim, proved to be best fungicide candidate for management of Alternaria alternata causing root rot disease to fenugreek.