Apr 7, 2007

Emerging Federal Rules Drive Blueberry Growers to Try New Insecticides

Blueberry growers currently are getting pretty good pest control with the pesticides they have available. So why would they be interested in new products, especially ones that cost more and might be more difficult to use?

The answer is government regulation. Guthion and Imidan, two insecticides that work well and fill a key niche in blueberry production, may not be around much longer.

“The EPA is currently evaluating Guthion and will make a decision this fall that determines whether blueberry growers will keep or lose this product,” said Rufus Isaacs, a Michigan State University (MSU) small fruit entomologist.

As blueberry harvest was nearing, he was speaking to growers in a large steel-clad packing shed next to the blueberry fields at Cornerstone Ag, operated by the Bodtke family near Grand Junction, Mich.

Cornerstone Ag is one of six Michigan blueberry farms cooperating with a team of research and Extension personnel from MSU in the blueberry RAMP project. John Wise and Keith Mason are other MSU entomologists working on the project with Isaacs.

“The project’s overall goal is to test new reduced-risk insecticides within an IPM program at commercial blueberry farms and deliver that information to the blueberry industry,” Isaacs said. “We aim to learn about the efficacy of new insecticides on target pests, their activity on natural enemies and pollinators. Whether new pest problems will appear and the economics of transition to insect management programs without organophosphate or carbamate insecticides. This project will help us understand how to best use new insecticides so growers are ready for potential future regulations.”

RAMP stands for Risk Avoidance and Mitigation Program. RAMP was initiated in 2000 in response to the Food Quality and Protection Act of 1996, said Robert Nowierski, RAMP program director with the USDA’s Cooperative States Research, Education and Extension Service. Since then, more than $26 million has been awarded to land grant university researchers working to evaluate alternatives when certain pesticides might be banned in fruit, vegetable and field crop production.

The blueberry project involves research and Extension teams from the primary blueberry-producing states of Michigan, Maine and New Jersey.

“The pest complex and the problems are different among the states,” Isaacs said. “Maine grows low-bush berries under less insect pressure. New Jersey and Michigan grow high-bush berries, but New Jersey has more problems with blueberry maggot and less with Japanese beetles than does Michigan.”

The year 2005 was the third of this four-year project.

In general, results so far show:

1. Some of the alternative insecticides work as well as the current options.

2. They are not as easy to use. Application timing, for example, is sometimes critical.

3. No new pest outbreaks have been detected.

4. Insect control costs more when using some of the newer insecticides.

In the project, growers agree to devote some acreage to a spray program chosen for its lower risk to the environment, workers and consumers and compare that to the programs they use on the rest of their farms.

In 2003, the six Michigan farms spent an average of $68.52 per acre for insect control in the standard program and $180.30 in the RAMP program, a difference of $111.78. The 2004 results were similar, $55.31 compared to $151.11, a difference of $95.80. The number of spray applications was about six in either program, but varied widely by farm.

In a standard program, growers attack cranberry and cherry fruitworms early in the season with Bacillus thuringiensis, which is safe for pollinators at work in the blossoms. After petal fall, they shift to Guthion, Imidan, Lannate or Asana, all of which are toxic to pollinators and other beneficial insects.

By mid-season, the pest complex changes to Japanese beetles, aphids and blueberry maggots, and the standard approach is to spray with Imidan, Sevin, Malathion, Asana or Lannate.

In the early-season RAMP program, growers continue to use Bt’s like DiPel, but also use Confirm, which is highly toxic to moth larvae, Isaacs said. It works by inducing a premature, lethal molt. It is effective against fruitworms, leafrollers and other moths, and is safe for bees.

Since it must be ingested, it requires “really, really good” coverage, Isaacs said ¬– and it costs twice as much as Guthion. Another product, Intrepid, not yet labeled for blueberries, works like Confirm but even better, he said.

In the later season, the RAMP program calls for SpinTor and Provado for control of maggots, leafrollers and Japanese beetles.

Japanese beetles have proven tough to handle. MSU entomologist John Wise said “it drives the control program in June and July.” Last year, the team experimented using Admire to treat sod alleys and perimeters in the blueberry fields and kill the white grubs before they can emerge as beetles.

It worked ¬– that is, it killed 95 percent of the grubs. But because the beetles are so widespread and feed and breed widely outside the blueberry fields, “others just fly in,” he said. The treatment didn’t result in an effective control measure when applied to an individual field.

Another part of the work is focusing on beneficial organisms. When toxic sprays are reduced or removed, you begin to see many beneficial insects working in the plantings. MSU entomologist Keith Mason is monitoring tiny wasps that parasitize aphids, ground beetles that forage on the soil as well as ants that are active throughout the blueberry fields.

“Significantly more lady beetles, ants and spiders were found on bushes in RAMP fields,” he said. “We’re trying to find out what the ants eat. We think they attack leafroller and fruitworm larvae.”

Some of the alternative pesticides in the RAMP program have proven valuable enough for the growers to adopt.

“We like Confirm better than the Bt’s,” said Larry Bodtke, “and we’ve already switched.”

About the program, he said, “I’m glad MSU was able to get the funding. It reflects the realities of what’s happening in Washington. There are some challenges we face using these new materials, like narrower application windows and shorter residuals. We found from this program that we’ll probably have to buy another sprayer because the application window is so narrow we have to spray more acres in a shorter time.”

Cornerstone Ag is a 750-acre blueberry farm in Grand Junction started by Ron and Phyllis Bodtke 35 years ago. Today, it supports four families – Ron and Phyllis, their sons Larry and his wife Leanna and Tom and his wife Arlene, and their daughter Kay and her husband Lupe Trevino and their children. Other western Michigan blueberry growers in the RAMP project are Joe DeGrandchamp, Karlis Galens, Bob Carini, Rick Kiel and Al Ochoa.