Journal of Krishi Vigyan

A laboratory experiment was carried out at the Soil and Water Testing Laboratory of Krishi Vigyan Kendra, Kerala Agricultural University, Sadanandapuram, Kollam, Kerala to evaluate the sensitivity of entomopathogenic fungi (EPF): Metarhizium anisopliae, Lecanicillium lecanii and Beauveria bassiana to pre-mix herbicides. The herbicides used for the in vitro study were Metsulfuron methyl + Chlorimuron ethyl, Cyhalofop-Butyl + Penoxsulam, and Pretilachlor + Bensulfuron methyl which are the popular herbicides among the rice farmers. The experiments were laid out in a completely randomized block design with 4 treatments and 4 replications separately for each entomopathogen. Radial growth and percentage inhibition of entomopathogenic fungi observed in the media poisoned with respective herbicides were recorded. Percentage inhibition was rated using Hassan’s classification chart. During all stages of observation, the growth inhibition of M. anisopliae ranged between 1.79% to 10.65% and it was rated as harmless. The radial growth of the fungus was higher in control plates which were statistically similar to fungal growth in petridishes poisoned with herbicides. With respect to L. lecanii it was seen that percentage inhibition was below 50% in the treatments involving the herbicide Metsulfuron methyl +Chlorimuron ethyl and Cyhalofop-Butyl + Penoxsulam, whereas Pretilachlor +Bensulfuron methyl treated plates showed maximum growth inhibition of 57.70%. The growth of B. bassiana was slow irrespective of the herbicide treatments and the treatment involving Metsulfuron methyl +Chlorimuron ethyl registered the lowest growth inhibition compared to Cyhalofop-Butyl+ Penoxsulam and Pretilachlor+Bensulfuron methyl. The percentage inhibition ranged from 22.33% to 87.57%. The results indicated that M. anisopliae was compatible with all the three tested herbicides and L. lecanii was compatible with Metsulfuron methyl +Chlorimuron ethyl and Cyhalofop-Butyl + Penoxsulam whereas Pretilachlor +Bensulfuron methyl was slightly harmful to L. lecanii. With respect to B. bassiana, Metsulfuron methyl +Chlorimuron ethyl was slightly harmful to the fungal growth while Cyhalofop-Butyl + Penoxsulam and Pretilachlor +Bensulfuron methyl were moderately harmful.