Killing turfgrass pests traditionally has been a rather imprecise science, but researchers are developing methods to more surgically strike at troublesome insects.

The new techniques are potentially more effective and more environmentally sound than conventional insecticide application. They hone in on white grubs, mole crickets and other pests where they live and do their damage - beneath the turf - instead of spraying the ground above, said Entomologist Frederick Baxendale, who's part of the University of Nebraska multidisciplinary turfgrass science team working on the project. It's "the wave of the future" in turf-pest control, he said.

"There's a control advantage and an environmental advantage," the Institute of Agriculture and Natural Resources researcher said. "You get the insecticide off the soil surface and into insects' feeding area ... It may mean we can reduce the amount of insecticide we have to use. Or we may be able to use more benign kinds of insecticides."

The industry-funded research, which Baxendale's team has been conducting for about six years, focuses on two methods to get at insects underground. One uses equipment to slice grooves or punch holes in the turf and insert insecticide. The other injects liquids at high pressure into the ground as deep as 4-6 inches.

The slicing approach can use both granular and liquid insecticide, but can damage turf if overused. Recent research by the IANR team, which includes Biological Systems Engineer Robert Grisso, focused on the liquid- injection technique to control white grubs and black cutworms.

In the latter tests, the equipment's nozzles sprayed water only at pressures of up to 5,000 pounds per square inch, blowing apart cutworms feeding on the turf surface. Tests on white grubs evaluated the efficacy of three types of insecticides injected with the same equipment.

The chemical treatment of white grubs has topped the 90 percent kill rate with certain kinds of insecticides; that's the threshold necessary for treatment to be useful.

But more research is needed to further hone the water-only - or mechanical - approach. In recent tests, only 56 percent of the black cutworms were eliminated, even with two passes over the turf. More passes than that can damage turf, so researchers are looking at the effect of spacing nozzles more closely and increasing the pulse rate, Baxendale said.

Anthony Weinhold, an entomology research technician and graduate student, is particularly eager to improve the mechanical approach. "I hope that someday we can control many of our turfgrass pests with plain water," he said.

Likely, these techniques will be most useful in large-scale uses such as golf courses, parks, industrial grounds and athletic fields. So far, John Deere, which has been the key funding source for Baxendale's research, has sold most of its subsurface injection equipment in Europe and Asia. For those customers, reduced pesticide use ultimately offsets the equipment expense.

It's possible this technology someday will be applicable to home-lawn equipment, Baxendale said.

In addition to John Deere, Rhone Poulenc, Zeneca, Novartis, Dow Chemical Co. and Bayer helped fund this research.

- Daniel R. Moser

This graphic illustrates how liquid insecticide or water can be injected at high pressures 4-6 inches into the ground to get at white grubs and other pests where they live.

Anthony Weinhold, an entomology research technician, operates the John Deere RZI 700, which injects liquids at high pressure into turf to kill pests underground. This and similar equipment is potentially more effective and environmentally sound than traditional above-ground treatments.