Efficacy of in-furrow zinc phosphide pellets for controlling rodent damage in no-till corn

Plagues of rodents in field crops have been a problem of human societies for centuries. These problems diminished with the onset of effective herbicides and clean farming practices in the 1960s, but there has been a resurgence of rodent irruptions in cropfields since the advent of conservation tillage systems. We examined the efficacy of in-furrow applications of 2% zinc phosphide (Zn3P2) pellets (27.5 kg ha−1 [5 lb acre−1]) at planting for the control of rodent damage in no-till corn. Three independent field studies were conducted in northeastern NE, southern IL, and southern IN. Vole populations in the most severely damaged fields (IL) ranged from 104 to 138 active colonies ha−1. Zn3P2 reduced yield loss in the three study areas by 7–34%. Projected economic returns ranged from US$1044 to US$5360, based on representative 64-ha fields and a net profit of US$250 ha−1. Benefit:cost ratios ranged from 1.1 to 5.6:1 and were directly related to vole population levels. To prevent rodent damage in no-till cornfields, we recommend an integrated pest management approach that incorporates the use of a combination of the following techniques: rodent population monitoring, economic thresholds, mowing, early pre-plant herbicides, broadcast whole-kernel corn, and in-furrow applications of Zn3P2 pellets.