The newest potato leaf-hopper-resistant alfalfa varieties can dramatically increase seeding-year yields, says an Ohio State University forage agronomist.

In 2001 trials, glandular-haired varieties cut first-year yield loss by 82% compared to smooth, susceptible varieties, says Marc Sulc. Up to 1 ton/acre more dry matter was harvested in the seeding year with resistant varieties.

"The industry has come a long way in increasing the level of resistance in alfalfa cultivars," says Sulc. "A few years ago, varieties showed 35% resistance, at best. Now varieties have 75% or better levels of resistance. There's no question farmers should be growing resistant varieties if they aren’t carefully scouting and managing their alfalfa for leafhopper damage."

Leafhopper feeding stunts plants, reducing yields. The reduction can be as high as 20-25% for the entire growing season and 30-50% for a single cutting, depending on leafhopper populations.

"The best ways to control the leafhopper are to use insecticides, resistant varieties or a combination of both," says Sulc.

In the Ohio State trials, resistant varieties lost yield only in the first cutting. In later cuttings, the yield was the same as that of sprayed susceptible varieties.

"This means that a farmer may only have to spray once in a seeding year, saving on insecticide costs," says Sulc.

"The potato leafhopper is the most serious insect pest of forage production year in and year out," he adds. "By planting resistant varieties, a farmer has the potential to save on insecticide applications and increase his yields when leafhopper populations get ahead of him."

For more information on the trials, contact Sulc at 614-292-9084 or sulc.2@osu.edu, or log on to www.ag.ohio-state.edu/~perf