October 2, 2009

White grubs are causing significant damage to pastures in Butler County. (Photo by Michael Rethwisch)

White grubs are causing extensive damage to smooth brome hay fields and pastures in southeast Butler County. Pastures that should be actively growing and producing copious amounts of green grass from the 6 inches of rain the past few weeks are instead turning brown. In many cases large areas (10-30 acres of the pasture/hay field) have been almost completely killed.

In addition to the pasture loss, erosion may be a problem this fall and spring in affected areas that don’t have an effective root zone to hold top soils in place.

Identification

In these pastures in southeast Butler County, white grubs were easily recovered from the root area, and upon initial examination were identified as a Phyllophaga spp. They were further identified as Phyllophaga lanceolata by Jim Kalisch of UNL’s Department of Entomology.

The Phyllophaga species of beetles usually has a three-year life span. This is consistent with local growers who reported they had white grub problems three years ago. Some pasture areas have been disced and re-seeded, but concern remains that grubs will feed on the roots of newly planted stands and kill them. Grub feeding would also be expected to continue next spring.

Management

Chemical control of white grubs in Nebraska pastures remains difficult at best, and natural biocontrol options such as skunks and raccoons can damage turf.
 

Michael Rethwisch
Extension Educator, Butler County