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Pest-Free Apples…Naturally!

Orchardist Dale Secher speaks for many Wisconsin fruit growers when he says that he cares about his customers as much as his bottom line.

Most Wisconsin fruit growers sell their produce locally, either through grocery stores or direct sales to customers. They have a strong interest in safeguarding the health of their customers, who may literally live next door.

“I put the environment and consumer health ahead of my own personal health, if necessary,” said Secher, who practices integrated pest management, or IPM, at his orchard near Oregon. IPM relies on careful management, monitoring, and biological interventions, such as beneficial insects, to minimize the use of chemical sprays. This reduces production costs by lowering input expenses.

Other apple growers, such as Bob Johnson of Gays Mills, have taken integrated pest management one step further. Johnson manages his certified organic orchard without any synthetic chemicals or fertilizers. Premium prices for his organic crop more than compensate for reduced yields resulting from pests and diseases.

The Center for Integrated Agricultural Systems at the University of Wisconsin-Madison builds partnerships between world-class fruit researchers and innovative farmers such as Secher and Johnson to research pest control strategies that reduce production costs, improve the environment, and protect consumer and farmer health.

Researching alternatives to traditional pesticides
Thirty-five miles from the nearest stoplight, Johnson”s Turkey Ridge Organic Orchard sits atop a rolling ridge in Wisconsin”s Kickapoo River valley. Despite its remote location, customers travel from as far as Chicago and Milwaukee to purchase his apples. With more than 140 acres planted to 15,000 trees and 22 varieties, Turkey Ridge is the largest commercial organic apple orchard in the Midwest.

Apples and other orchard crops can be extremely challenging to manage organically. Most organic farmers rely on crop rotations to break pest and disease cycles. Because rotation is not an option in orchards, organic farmers such as Johnson depend on disease-resistant varieties, alternative sprays that are acceptable under organic certification, and a healthy ecosystem to produce a quality crop.

Turkey Ridge is planted entirely to scab-resistant apple varieties such as Liberty, JonaFree, Priscilla, and Freedom. Late-summer fungal diseases such as sooty blotch and flyspeck, however, are especially troublesome in organic orchards. In warm, wet summers, these diseases can cause severe losses. Johnson is working with researchers at the UW-Madison”s College of Agricultural and Life Sciences to find alternative controls for these diseases.

Plant pathologists Patricia McManus and John Andrews and research specialist Jessica O”Mara tested several alternative fungicides in Johnson”s orchard. They found that potassium bicarbonate or a mixture of an amino acid (methionine) and a vitamin (riboflavin) reduced sooty blotch and flyspeck on three scab-resistant apple varieties-JonaFree, Prima, and Freedom. All of these substances are allowed on certified organic farms.

Although McManus is still analyzing the results and repeating experiments, she is optimistic about these alternative sprays. “With these treatments, we saw a 50 to 90 percent improvement in sooty blotch and flyspeck control,” she said. The variability might be explained by differences in weather and the orchard environment during the two-year trial.

Managing primary insect pests that do not have effective natural predators is a big challenge for organic apple growers. Plum curculio is Johnson”s biggest problem. Plum curculio overwinters in brush piles, so Johnson manages it by piling brush in his orchard and burning it in winter. He controls coddling moth by disrupting its mating with pheromones. He diverts the apple maggot fly from his crop with bright-red sticky traps that resemble apples.

Fifty to 60 kinds of insects damage Wisconsin”s apple crop. Many are secondary pests that can be controlled by their natural predators. Johnson controls aphids, mites, leafrollers, leafminers, and other secondary pests by encouraging beneficial insect populations in his orchard. He worked with CALS entomologist Dan Mahr to develop an orchard environment that attracts and supports insects that prey on apple pests.

A few years ago, Mahr”s graduate student, Paul Whitaker, planted thousands of row feet of perennial flowers such as Echinacea that harbor these predators between the rows of trees in Johnson”s orchard. Mahr and Whitaker selected hardy, non-invasive plants that won”t compete with the apple trees. The plants bloom throughout the season, providing food and shelter for ladybugs, lacewings, and parasitic wasps from early spring until late fall. Broad-spectrum pesticides could destroy these native predators.

“Broad spectrum organophosphates and carbamates can have a stronger impact on beneficial insects than on apple pests,” said Mahr. “When farmers control primary pest species with broad spectrum pesticides, they sometimes destroy the populations of predator insects that can control their secondary pests.”

Although Mahr and Whitaker are still analyzing their results, preliminary findings show that beneficial insect populations increased where the flowers were planted. “We were able to show an increase in the numbers of natural enemies of aphids in particular, and probably also leafrollers,” said Mahr. “It was more difficult to measure our impact on leafminers, as there were already adequate parasites in the orchard to keep the leafminers under control.”

For Johnson, building a diverse ecosystem lies at the heart of his organic orchard management. “It took us ten years to build the ecosystem that we have, and it is still fragile,” he said. “You think you have it figured out, but a lot of times you don”t.”

Reducing pesticide use through IPM
Organic apple production is not for everyone, particularly if an orchard is already planted to varieties such as Macintosh, Delicious, and Cortland that are susceptible to scab.

Secher and many other Wisconsin apple growers use IPM to minimize pesticide use and eliminate spraying fruit near harvest time. Secher has reduced pesticide applications through encouraging beneficial insects, monitoring pest populations and disease conditions, and using common sense.

“We don”t eliminate the option of using chemicals,” said Secher, “but we”re very, very careful how we use them, and when we use them. We”re trying very hard to cut back.”

Secher has not used a miticide in his orchard for 15 years. Instead of spraying for mites, he simply lets grass grow between his orchard rows. The grass provides a habitat for beneficial mites that prey on damaging mites such as the European red mite. In addition, Secher tries to use pesticides that won”t harm his beneficial mite population.

Generally, apple growers keep their orchard floors clean because grass can harbor mice and compete with the trees. Secher uses guards around the trees to protect them from mouse damage, and his yields have not suffered from letting the grass grow.

Secher subscribes to an online information service for up-to-date disease and insect monitoring information. With the cooperation of several Wisconsin apple growers, specialists with the Wisconsin Department of Agriculture, Trade and Consumer Protection monitor pest levels and weather conditions around the state. The data are reported and interpreted on an Extension Web site. By using this service and monitoring his orchard for insect and disease problems, Secher sprays only when absolutely necessary.

“Most good Wisconsin growers use monitoring and IPM practices to cut back on sprays,” he said. “The amounts of pesticides being used now are much less than 10 or 15 years ago.” Still, some apple growers spray according to a set preventative schedule regardless of the actual threat of pest and disease infestations.

Like most apple growers, Secher uses fungicides to control scab. He tries to control this disease before the trees bloom, however, to avoid exposing the fruit to the fungicides. By spraying early, he controls later outbreaks by eliminating infections that go on to produce spores and more disease.

“We do everything culturally possible to eliminate the environment required for scab and other fungal diseases,” said Secher. “We keep our rows narrow, and we planted our orchard to take advantage of the prevailing winds. Fungi like wet conditions, so we do everything possible to keep our trees dry. This really cuts down on the scab problem.”

Secher, who also raises strawberries, raspberries, and vegetables, generally tries to avoid using any pesticides on his plants after they bear fruit. Because the apple maggot and coddling moth can leave him with wormy fruit, however, he sprays his orchard after the fruit is set. He discontinues all pesticide applications on his apples 30 days before harvest. As a result, his yields can suffer slightly from late summer diseases such as sooty blotch and flyspeck.

Secher was able to reduce much of the risk of switching to IPM practices by switching gradually, trying out one practice at a time. His yield losses declined as he gained experience with the new management strategies.

As far as Secher is concerned, however, any yield losses he may suffer from his IPM program are less important than the health of his customers and the environment. “If I”d stuck by the textbook and put on every chemical that was indicated in the preventative way, then I probably would have had higher yields,” he said. “But I don”t think that is the responsible thing to do.”

Food Quality Protection Act
Secher and Johnson have adopted management strategies that reduce their need for pesticides for a number of reasons-customers” health concerns, environmental quality, personal safety, and reduced input costs. As the Environmental Protection Agency (EPA) implements the Food Quality Protection Act, however, more farmers may soon have a reason to consider IPM.

The act creates a single, health-based safety standard for pesticide residues in food and the environment. The EPA is developing this standard after examining all possible ways that people are exposed to chemicals. For example, organophosphates are used for household extermination and yard pest control as well as in agriculture. The EPA is basing its standard for organophosphates on all of these possible exposures.

To protect infants and children, the EPA is setting lower pesticide residue tolerances for foods they eat frequently. Because infants and children eat lots of apples, the Food Quality Protection Act may strongly affect how apple growers manage their pests.

The EPA has identified eight insecticides and five fungicides used in Wisconsin”s apple orchards as high-risk to human health. Many of the organophosphates and fungicides used on apples are reproductive toxins, and some pose thyroid risks. Organophosphates can disrupt neurological function, causing dizziness, nausea, and confusion. Although these health risks clearly affect farmers and farm workers, it is uncertain whether chemical residues on apples impact consumer health.

Many apple growers worry that they will lose money if commonly used pesticides such as Guthion, Imidan, Benlate, Captan, and Mancozeb are further restricted in their orchards. The EPA has set tougher standards for worker protection with Guthion, and will strengthen worker protection standards for Imidan in the next year.

Although implementing the Food Quality Protection Act will be a long process with an uncertain outcome, Mahr doesn”t believe it will cause extreme economic hardship for apple growers. “The few decisions made by the EPA so far have had a minimal impact,” he said. “Future decisions may not have much of an impact, and we have the tools to compensate.

“There is a whole bucketful of new insecticides on the market that will have less of an impact on beneficial insects and the environment,” he continued. Switching may help farmers control secondary pests, as the new products may not kill the beneficial insects that can control these pests.

Both Secher and Mahr see some drawbacks to these more targeted pesticides. Pests can develop resistance to these products, which means that they may be ineffective in a few years. Growers may need to apply several pesticides, rather than just one broad-spectrum product. Secher wants more research on how these chemicals will interact, and the health impacts they may have when used in combination.

These new pesticides cost more than traditional products, which could pose a problem for growers. According to Secher, the apple industry survives on extremely tight margins. Apples are a permanent crop, and growers can”t plant something different for a year or two because input costs are too high. If they don”t receive a higher price to compensate for increased input costs, many may go out of business.

“The consumer will have to pay the price if less expensive, more effective materials go off of the market,” said Secher, who sees hope for farmers who manage their operations carefully and develop new enterprises to increase their profits. “The better managers will find new markets and develop value-added products. Most Wisconsin orchards deal directly with the public. Having a little bakery or restaurant on the side can save a lot of orchardists.”

McManus believes that Wisconsin consumers will pay more for locally grown apples. “Given the choice, in the fall people will choose a locally grown apple over a Washington apple, and they will probably be willing to spend more for it. Washington apples and Wisconsin apples are almost two different products.”

Apple growers can ease the transition to new pest management practices by mentoring one another and working with CALS researchers. Secher says that he is willing to share his management strategies with any grower who is serious about making the switch. By sharing information with other growers, his business benefits from overall improvements in the quality and reputation of Wisconsin apples.

McManus said that researchers learn a lot from working with farmer partners. “From our perspective, the growers think of things that we miss,” she said. “They can think of the whole orchard as a system better than we do.”

Secher feels that switching to IPM will not only benefit consumers, it will also keep Wisconsin agriculture sustainable over the long haul. “I think that”s what we need to do in agriculture, to maintain as much sustainability as possible,” he said. “I think that IPM allows you to do that.”