Economic injury level of Aphis craccivora Koch in black gram.
The economic injury level (EIL) of A. craccivora on black gram (cv. T-9) sown during the kharif season of 1999 (15 September) was found to be 10.82 aphids/plant in a field experiment conducted at Assam Agricultural University, Jorhat, Assam, India. The aphid infestation in mid-September sown crop reached EIL within the first week of November when the crop was in full bloom stage. Insecticidal application needs to be given during the first week of November before the EIL is reached. The observed and expected avoidable yield losses due to this pest were 461.00 kg/ha and 438.73 kg/ha, which were 51.22 and 50.67%, respectively, of the yields under no exposure (full protection).