During the three years of study from 1996 to 1998, incidence of Nomuraea rileyi on Spodoptera litura in groundnut was noticed between 32nd to 40th standard week (SW) with peak activity in the 37th standard week (Sep 10-16) during 1996 and 1997 and in the 34th (Aug 20-26) during 1998. Similarly in soybean fungal activity was noticed from 32nd to 38th standard week recording peak in the 35th , 34th and 33rd standard week during 1996, 1997 and 1998, respectively. Fungal incidence was comparatively late by one or two weeks in potato. The activity of the fungus commenced from 33rd (SW) and prevailed upto 39th standard weak attaining maximum in the 37th during 1996 and in the 35th standard week in 1997 and 1998 respectively. Thus the most favourable period of the season for the fungus was from 32nd to 40th week i.e. first week of August to first week of October. Among the three crops, maximum incidence was noticed in groundnut (27.12%) followed by soybean (22.12%) and least in potato (13.75%). Correlation studies between weather parameters and disease incidence of /V. rileyi on S. iiture indicated positive significant influence of afternoon relative humidity in groundnut (0.87 **), Soybean (0.72*) and potato (0.71*) during Kharif season.