As part of a research experiment believed to be among the first of its kind, Koan is using pigs to help protect his fruit from the plum curculio, a tiny insect that is among the most destructive apple pests.
More than two dozen porkers patrol his orchard, gobbling down fallen, immature apples containing the beetle's larvae. After a successful trial run late last spring, he and some researchers at Michigan State University are preparing for year two of the experiment at AlMar Orchards and Cidery in eastern Michigan.
They hope their work will someday help fruit growers throughout the world reduce the use of pesticides while diversifying their agricultural operations, as he is doing. He plans to periodically sell off the offspring of his four original hogs, keeping only those he needs.
"I'm not ready to say that everybody should run out and do this but I'll tell you, after the first year, I'm a whole lot more optimistic and excited by the possibilities," said Dave Epstein, a tree fruit pest-management specialist at the university and the project's lead researcher.
The quarter-inch-long plum curculio is particularly difficult for growers like Koan to control because no good organic controls have been developed for them. The beetle can be controlled conventionally, often with the pesticide azinphos-methyl. But the U.S. Environmental Protection Agency is phasing out the powerful pesticide, marketed under the trade name Guthion, because of the risks it poses to farm workers and to the environment.
Adult female curculios cut crescent-shaped flaps in the skin of newly formed apples and lay their eggs inside, where they hatch. The beetle larvae burrow into the center of the young fruit, making it drop prematurely in late June or early July.
After spending about two weeks inside, the larvae migrate from the fallen fruit into the soil, where they pupate for 10 to 12 days before emerging as adults to attack the remaining fruit and start the cycle all over again.
Koan decided to try to find an animal that would eat the fallen apples as they lay beneath the trees, before the bugs became adults, but he had a few misses before he settled on pigs.
First, he tried using some chickens.
"All they did all summer long was lay around under the trees when it was hot and just sunbathe, you know, kind of like on the beach," he said.
Then a neighbor's dogs got to the birds. "So that was a bad idea."
He next tried guinea fowl, an energetic wild chicken. They did a "fantastic job" _ until some birds of prey discovered them at the orchard.
Then Koan remembered how his grandfather would drive his pigs into his orchard so they could feed on fallen apples.
So Koan obtained some Berkshire pigs, with the idea of breeding them not only so they would eat the fallen apples and kill the beetle larvae but also for slaughter as organically raised meat. He bought a boar and three sows, and now has 27 pigs.
When the infested apples fell in June, the pigs were released into three one-acre sections of the orchard. The researchers compared those three plots with three other one-acre plots where the swine didn't go, and found that the pigs did even better than expected.
Left in the orchard for three days, the pigs gobbled down 98 percent of the fallen apples. Tests showed virtually all the larvae were digested.
"The little guys moved through like a pack of Hoover vacuums," Epstein said.
The researchers found that in the plots where no pigs were allowed, five times as many plum curculios were counted.
Epstein got a one-year grant from the U.S. Department of Agriculture to study the effect of the pigs on the orchard last year and has applied for a four-year grant.
Koan, 60, took over the farm in Clayton Township, near Flint, from his parents. In the past 15 years or so, while trying to diversify his business, he has moved into organic production, phasing out most chemicals to fight off the pests, weeds and diseases that could harm his fruit.
"I think if my granddad was alive today and he saw how excited I am about doing this and this information that we're gaining on this," said Koan, "he would just look at me and say, 'Jeez, you're stupid. You didn't know that?'"