August 7, 2009

August plantings of alfalfa work well, especially when you have moisture, but they can be quite vulnerable to grasshopper feeding.

Few things are more frustrating or more costly than when these tender, young seedlings are devoured by grasshoppers. While grasshoppers are a threat somewhere every year, reports are particularly high in western Nebraska this year.

Begin by scouting for grasshoppers before you plant. If you find more than two or three grasshoppers per square yard or more than 10 grasshoppers per square yard in field margins, apply an insecticide.

Treat field margins before new alfalfa seedlings emerge.

Orthene has worked well in field margins, but is not labeled for use directly on alfalfa, just the field margin. Other options for field margins include the pyrethroids, Asana, Proaxis, Warrior, and Mustang MAX, which also could be used in the seeded field after crop emergence, if needed. Since many grasshoppers are getting large, use the highest rate allowed on the label. Additional information on registsered insecticides is listed on the Department of Entomology Web site.

With any insecticide, be careful to avoid injuring bees and other important pollinating insects. Consider time of day when spraying and the toxicity of the insecticide, and avoid areas with blooming plants.

Also be sure to carefully read and follow all label directions.

August can be a great time to start a new alfalfa field, but be careful to protect that investment with proper grasshopper control.

Bruce Anderson
Extension Forage Specialist