Effects of threecornered alfalfa hopper injuries in early maturing soybeans

Three cornered alfalfa hopper (TCAH) Spissistilus festinus (Say) is a common pest of soybean during early vegetative growth as well as during reproductive growth. The primary damage from this pest is girdling of the main stem during vegetative stages of plant development and girdling of the petioles during reproductive stages. Previous research determined that densities of sucking pests like TCAH are higher in the early soybean production system. Yield losses are greater during reproductive stages of soybean than vegetative stages. However, it is likely that some reproductive stages of soybean are more vulnerable to damage than other stages. We infested soybean plants with varying pest pressures (0, 1 and 3 TCAH adult/plant) at reproductive stages starting from R3 through R7, using 6ft X 6ft field cages. Plant samples were collected at each growth stage and examined for stem and leaf petiole girdling. Data collected included number of girdles on main stem/leaf petiole and relative position of these girdles with respect to nodes on the plant. Later in the season, we harvested the treated plots to compare whole plot yields and quality of beans.