Seasonal prevalence of spotted pod borer, Maruca testulalis (Geyer) infesting green gram

Abstract

A field experiment was conducted at Instructional Farm, College of Agriculture, Junagadh Agricultural University, Junagadh in 2023 during the kharif season to investigate the seasonal incidence of spotted pod borer, Maruca testulalis (Geyer) infesting green gram. The activity of M. testulalis commenced in the 38th standard meteorological week (SMW) in fourth week of September, with 0.51 larval population and 8.93 per cent pod damage during 39th SMW. During the third week of October, the 41st SMW recorded the first peak with 2.76 larvae per plant and 31.77 per cent pod damage. After a slight decrease in larvae per plant and per cent pod damage, a second peak was observed in the 44th SMW, in first week of November, with 3.20 larvae per plant and 36.26 per cent pod damage. In the following weeks, there was a decrease in the larvae per plant and per cent pod damage, reaching its lowest during the 47th SMW, which fell on the fourth week of November, with 0.68 larva(e) per plant and 6.96 per cent pod damage. The study on the correlation of M. testulalis larval population with weather parameters exhibited a significant positive correlation with maximum temperature (r = 0.675*) and significant negative correlation with wind speed (r = -0.669*). While, per cent pod damage exhibited a highly significant positive correlation with maximum temperature (r = 0.747**), a significant positive correlation with bright sunshine (r = 0.687*) and a significant negative correlation with wind speed (r = -0.695*).