Killing two moths with one stone

03/01/2009 02:00:00 AM

By Renee Stern
Contributing Editor

By building a multipronged attack against codling moth larvae into a single sprayable, biodegradable package, researchers hope to create a more cost-effective control.

The concept would replace cardboard traps now banded around tree trunks with a cellulose-based foam that offers similarly attractive pockets to larvae seeking protected refuges for their cocoons.

Applying foam with a sprayer cuts labor costs significantly compared with wrapping cardboard for each moth generation by hand around individual trunks, says Peter Landolt, research leader at the U.S. Agriculture Department’s Agricultural Research Service in Wapato, Wash.

The foam should last through the season but then begin to break down and wash away, Landolt says.

But labor savings are only one advantage over cardboard bands. Foam also provides a moist environment needed by entomopathogenic nematodes that attack and kill codling moth larvae, says Lerry Lacey, research entomologist at the Wapato station.

Other tactics the researchers are investigating include impregnating the foam with low doses of a pyrethroid pesticide and an aggregating pheromone that lures larvae into what has become a “death strip,” Landolt says.

Hardware store provided inspiration
Sprayable insulating foam from the hardware store triggered the idea. Easy to apply, it expands on contact and creates the desired air spaces. The problem, Landolt says, is “it’s indestructible. It’s designed to last hundreds of years.”

He and Lacey teamed up with Greg Glenn, lead scientist at ARS’ Albany, Calif., Bioproduct Chemistry and Engineering Research Unit, to develop a formulation better suited to orchard needs.

To host nematodes without harming them, the foam needs to be moist—but it also must be stable enough not to collapse. At the same time, it must be inexpensive and biodegradable.

“It’s kind of a tall order,” Glenn says.

Pulp fiber from the paper industry in a water-based slurry is the main ingredient, mixed with stabilizers, sawdust for added substance and an industrial foaming material.

Finding the right applicator turned into another challenge, he says. Too much shear as the material sprays from the nozzle can break the bubble structure.

Cost is critical to attract a wider market, Landolt says.

For organic growers, the cardboard bands now in use are a significant control method, so replacing them with a sprayable foam should produce more cost-effective results.

Adding in organic-friendly nematodes makes it even more attractive, he says.

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