Effect of Potato Leafhopper Injury on Yield and Quality of Resistant and Susceptible Alfalfa Clones123

Abstract

Twelve alfalfa clones representing a broad range of resistance to the yellowing caused by Empoasca fabae (Harris), were evaluated to determine the interrelationship between resistance to yellowing and changes in the yield and in the quality of forage. Some clones had high levels of resistance to yellowing despite large populations of leafhoppers, but when infestations were moderate to heavy, all clones had substantially reduced total growth, yield of forage, and quantity of such important qualitative components as carotene and protein. The changes in yield and quality of individual clones compared with uninfested counterparts were generally less for resistant than for susceptible clones. Digestible dry matter (dry matter disappearance) was affected little by potato leafhoppers, but none of the clones had measurable resistance to stunting. Infested plants consistently had much higher dry-matter content than uninfested plants, which tends to negate estimates of yield based on plant length and green weight.