Synchronizing pesticide use with pests' vulnerability helps save money

By MITCH LIES
Capital Press

AURORA, Ore. -- Reducing production costs on nurseries can mean the difference between sinking or swimming.

One place growers can look for cost savings is in pest control. In addition to saving on chemical expenses, reducing pesticide use can benefit the environment.

In many cases, growers can reduce pest control costs without lowering plant quality, Oregon State University Extension horticulturist Robin Rosetta said.

Often the key to meeting those goals is improved scouting, or insect monitoring, Rosetta said.

"If you catch things early, you often have more control options, some of which are cheaper," Rosetta said.

Also, early in their life cycles, insects generally are more susceptible to softer materials, such as insecticidal soaps and horticultural oils. Using softer materials allows producers to control problem pests without harming beneficial populations.

And in some cases, catching infestations early can help producers save product.

For example, the shothole borer, a tiny beetle that feeds on bark, sends out signals when it finds a food source. Catching the pest early and removing the infested shade trees can dramatically reduce pest-control costs and save product from damage.

Rosetta encourages producers to use traps, such as pheromone traps or funnel traps, to determine when insects are out and about. Also, learning an insect's life cycle can help producers determine when to treat.

Rosetta said she likes to find that point in an insect's life cycle when it is most susceptible and then target that life stage in her treatments.

In the case of rose midges, for example, Rosetta helped the Portland Parks and Recreation reduce treatments from 12 annually to one at Portland's Rose Test Garden. In addition to cutting costs, the single, well-timed treatment improved the efficacy of the department's pest control.

The work earned her the department's first Partner in Environmental Stewardship Award this spring.

Rosetta discovered the pest was best controlled when it is in the soil before it comes up the rose plants, she said. The early-season control also served to preserve beneficial insects on the roses, which were able to keep down midge populations during the season by feeding on the pests.

Rosetta has used a similar strategy to control the honeylocust pod gall midge.

Both pests can be extremely difficult to control with contact insecticides once they get established, in part because of their feeding patterns.

When spraying pesticides, Heping Zhu, an agricultural engineer for the USDA Agricultural Research Service in Wooster, Ohio, said growers can cut treatment rates dramatically without losing efficacy.

Zhu found that most nursery growers overspray, in part because treatment rates often are based on orchard treatments and because the industry often needs perfect plants to induce sales.

In five years of trials in Ohio, Zhu and his team used half the rate chemical companies recommend on labels and achieved the same effectiveness as full-rate trials.

Zhu found similar results whether using fungicides, insecticides, hard or soft materials.

The benefits of cutting back on rates are multiple, Zhu said. Growers can reduce environmental pollution, save money on product costs and reduce the number of stops for refilling a tank.

One key to achieving the same effectiveness with reduced rates, Zhu said, is application timing.

Staff writer Mitch Lies is based in Salem. E-mail: mlies@capitalpress.com.