By KEVIN WALKER
Michigan Correspondent

LANSING, Mich. — Peter McGhee, a research assistant at Michigan State University, loves his job. That’s because he helps growers obtain a better crop – and both he and they have been seeing results.

For the past few years he’s been working with apple growers in particular to help them defeat a major apple pest, the coddling moth. For his efforts, last year McGhee won the school’s Jack Breslin Distinguished Staff Award.

“I work with a really great team of people here at MSU,” he said.
The specific technique is insect pheromones. According to McGhee, scientists have been aware of pheromones for about 50 years, with the first registered pheromone for controlling crops finding its way into the market about 30 years ago. Scientists have been working with insect pheromones for 20-25 years.

Companies sell insect pheromone dispensers of different types, but they are not necessarily required to conduct thorough, scientific studies that prove the efficacy of their products, since they are organic.

“We showed how well the pheromone really works in apples,” McGhee said. “We were helpful in showing that the companies’ pheromones are effective.”

In 2004 McGhee and his colleagues started a project with eight apple growers, all in the Fruit Ridge part of the state, northwest of Grand Rapids. Originally, the project included about 800 acres of apple orchards. Other growers heard about it and, within three to four years, the total acreage included in the project ballooned to 2,000-3,000, with a total of 21 growers.

“I think it brought the growers together in a regional way to combat the moths,” McGhee said.

The coddling moth causes problems for growers by laying eggs on the fruit. It’s a major apple pest. The eggs hatch and the resulting larvae burrow their way inside the apples, destroying them.

Insect pheromone treatment works by disrupting the mating pattern of the moth in the hopes of cutting down on the moth population. It works like this: At the start of the growing season, the grower puts up dispensers filled with the pheromone. One common dispenser type is a tube-like structure that McGhee said looks like a straw. The pheromone bleeds through the wall of the straw. It takes 300-400 dispensers per acre to do the job.

The big disadvantage of the technique is the hassle of putting them up, he said. It costs about $100-$125 per acre to do this, plus all of the labor. It costs about the same to do this as two chemical sprays, but the treatment more than pays for itself.
“Once you put it up in the spring, it works for you throughout the summer,” McGhee said. “We’ve shown that growers reduce the number of sprays they used to use from six down to one to two per season. Some growers are able to get by with zero to one spraying.”

The dispensers confuse the males because they contain a large amount of insect pheromone, far more than a female coddling moth. Normally, the male finds the female by smelling it, but after it gets a whiff of what’s in the dispenser, it can’t find a female for an entire night.

The team is able to monitor the effectiveness of the treatment by putting up sticky traps with a smaller amount of insect pheromone to try to attract moths. If the treatment is working, there should be few moths on the sticky trap, McGhee said. He said that, before the treatment, thousands of moths might get stuck on a trap. After treatment is under way, there might be only one to five moths that get stuck.

Joe Rasch, an apple grower who participated in the program, agreed the treatment works. He’s been using insect pheromone on his crop for more than 10 years; for the past three years, he’s been using it on 90 percent of his 400 acres of apples.

“It’s brought the pressure right down, along with the insecticide,” Rasch said. “It’s going to make these insecticides last a lot longer. It takes quite a bit of manpower to put the dispenser up. The twin tube deal is a lot easier to put up. The bottom line is clean fruit and yeah, I’m happy.”

Rasch added with this system, moths can sometimes get in at the edge of an orchard, because it’s likely moths will be present in larger numbers outside the treatment area.

“The bigger the orchard, the better it works,” he said.

Both McGhee and Rasch stated another benefit of the pheromone treatment is an effective insecticide will stay effective longer, since there’s less chance for the moths to develop resistance.

Funding for the program ended in 2007, but according to McGhee most of the growers are continuing to use the treatment.

“They like the strategy because they don’t have to worry about moths for the rest of the season,” he said.