Development of Benzimidazole and DMI Resistance in Gloeosporium ampelophagum Causing Anthracnose of Grapes from Maharashtra State

Continuous use of carbendazim, difenoconazole and propiconazole has led to development of resistance to these chemicals in Gloeosporium ampelophagum. Among 37 isolates of G. ampelophagum, 97.30% population was highly resistant to carbendazim (minimal inhibitory concentration - MIC of 1.01 to 28549.43 μg/ml), 5.41% to difenoconazole (MIC of 25.63 μg/ml) and 10.81% to propiconazole (MIC 6.26 μg/ml). The development of resistance (R) against difenoconazole and propiconazole was high and development of highly resistant population (HR) was less when compared with carbendazim. The complete replacement of resistant population into highly resistant was due to continuous use of carbendazim. It was noted that difenoconazole and propiconazole are still suitable for the management of G. ampelophagum where selection pressure is less when compared with carbendazim. Carbendazim became unsuitable due to development of high resistance in G. ampelophagum. However, there will be future need to develop ‘resistance management strategy’ against difenoconazole and propiconazole.