December 14, 2007

Last summer many alfalfa fields turned yellow and stopped growing due to potato leafhopper damage.

For several years I discouraged using alfalfa varieties with potato leafhopper resistance. My reasoning was that leafhoppers are a problem in our area only occasionally, the resistance level was too low to be worthwhile, resistant varieties yielded less when leafhoppers were not a problem, and seed cost was much higher.

Now my recommendations have changed. New varieties have improved enough to make them worthwhile. The best varieties now have enough resistance to leafhoppers to make a big difference when leafhoppers are active. When leafhoppers are damaging alfalfa, yield of these resistant varieties often is 30-50% higher than that of susceptible varieties. In fact, it takes about three times as many leafhoppers to make it worth spraying these varieties as it does susceptible varieties. Plus, the yield drag has been practically eliminated.

Seed prices still are a bit higher for these varieties, so be sure you buy them only if you frequently have problems with potato leafhoppers. In northwestern Nebraska, west of Highway 281 and north of Interstate 80, these insects are rarely a problem. The potential for damage will increase the further east and south of this area that you are. The newer varieties with higher leafhopper resistance should be valuable to many alfalfa growers in this region, especially growers who depend on alfalfa as a major income source. If that describes you, these varieties should be worth the cost.

Bruce Anderson
Extension Forage Specialist