Managing pigweed flea beetle using insecticides and trap crop in Amaranthus viridis fields

Amaranthus viridis Linn, (Amaranth), or green amaranth, is grown by small farmers on the Delmarva Peninsula. The pigweed flea beetle is one of the key insect pests of amaranth. Here, the efficacy of organic insecticide (Neem-oil and Spinosad), conventional insecticide (Sevin), and hemp, Cannabis sativa (trap crop), was tested to manage the beetle and other insects in this 2-yr study. Spinosad and Sevin significantly reduced the number of insects in amaranth plants and increased the total fresh leaf yield. However, neither insecticide is registered for use in A. viridis in Maryland. Hemp as a trap crop was planted at 4 distance points from amaranth plants (control, 0.9, 1.8, and 2.7 m) in 2023. Hemp seems to be a good trap crop in the amaranth field, especially if it is planted at the appropriate distance (ie 2.7 m (҄≈3 feet)) from the amaranth plant. The damage by the beetles was reduced as the distance from the trap crop increased, possibly due to the beetles' movement pattern from the field's edge toward the amaranth plants. However, this study needs further investigation to understand the role of hemp phytochemicals in attracting or repelling the pigweed flea beetle or other insects.