Agronomics and Economics of Potato Leafhopper (PLH)-resistant Alfalfa Intercropped with Perennial Forage Grass for PLH Control

Potato leafhopper (PLH) is the most damaging alfalfa pest in the Northeast (NE). Forage grasses mixed with alfalfa can cause PLH to emigrate but may reduce forage quality. Some alfalfa cultivars have PLH-resistance, yet are not immune to PLH damage. The objectives are to compare PLH populations and densities, and forage yield and quality of a conventional alfalfa cultivar and a PLH-resistant cultivar both in monoculture and intercropped with grass, to conduct an economic analysis, and to share results in extension outreach. For conventional alfalfa not sprayed with insecticide, the alfalfa : grass mixture plots compared to the monoculture alfalfa plots averaged significantly lower PLH damage scores (2.7 vs. 3.2), lower number of PLH insects in 5 sweeps (19.4 vs. 30.0), and higher total season yield (2.11 t/a vs. 1.88 t/a (P