May 29, 2009

Grubs have been a problem in lawns for many years, so it's really no surprise that they have moved to pastures, especially those dominated by bluegrass. Growers in many counties in eastern and central Nebraska have reported grubs in scattered areas within pastures.

It was a bit of a surprise though when UNL entomologists discovered that these pasture grubs belonged to an entirely different genus (Dyscinetus)of grubs than those commonly found in lawns (Phyllophaga and Cyclocephala). This genus is not common and has not been thoroughly studied. Since grubs have been found in pastures throughout the growing season, they may be like the May/June beetle, which has a three-year life cycle that includes about 24 months as a grub. This is just my speculation, though.

Management

Control recommendations are limited at this point. Skunks, birds, and other animals like to dig up the grubs for food, leaving a pasture full of unproductive divots. Sevin is the only chemical labeled for pastures that can kill grub larvae, but it's not very effective in a pasture environment. Other pasture insecticides labeled for pasture use (Mustang MAX and Warrior) are likely effective on adults, but not on the grubs.

Good pasture management practices may be your best means of control.

• Plant grasses that are more productive than bluegrass.
• Develop and maintain healthy and vigorous pastures.

Grub problems may be here to stay and a pest we may need learn to live with.

Bruce Anderson
Extension Forage Specialist
Michael Rethwisch
Extension Educator, Butler County