A Re-Examination of Economic Injury Levels for Potato Leafhopper (Homoptera: Cicadellidae) on Soybean²

The potato leafhopper, Empoasca fabae (Harris), is an occasional pest of seedling soybean throughout the eastern United States. Economic injury levels (EIL) for E. fabae on soybean are not available for all vulnerable soybean stages, nor do they reflect current understandings of soybean response to injury or EIL calculation methodology. Damage terms were estimated for seedling soybean stages using curve-fitting techniques that consider the vulnerability of the expanding leaf tissue of seedling soybean. Yield loss for stage V1 soybean was 43.58 kg/ha/E. fabae/plant, for V2 was 20.41 kg/ha/E. fabae/plant, for V3 was 13.10 kg/ha/E. fabae/plant, and for V4 was 9.55 kg/ha/E. fabae/plant. Economic injury level matrices were developed to reflect changing economic conditions and management costs for V1 through V4 soybean. The EILs are 1.4 to 3.6 E. fabae/plant for V1 soybean, 3.0 to 7.8 E. fabae/plant for V2 soybean, 4.7 to 12.2 E. fabae/plant for V3 soybean, and 6.5 to 16.7 E. fabae/plant for V4 soybean.