Hogs Benefit Organic Apple Orchards

LANSING - Dec 5/07 - SNS -- Organic apple orchards can net significant reductions in plum curculio infestations if hogs are allowed to graze on dropped apples.

"Plum curculio comes into an orchard in the spring and lays eggs in the fruit, and the resulting worms, or larvae, develop in the apples, causing many to drop off the tree in mid-June or July," said David Epstein, tree fruit specialist with the Michigan State University (MSU) Integrated Pest Management Program. "The larvae exit the apple and tunnel into the soil before emerging as adults to start a summer generation.

"What the hogs do is interrupt that cycle," he continued. "If timed properly, they eat those dropped apples before the larvae have a chance to go into the soil and develop into adults."

Jim Koan, owner of AlMar Orchards in Flushing, brought three 150-pound Berkshire hogs (two sows, one boar) into the orchard. Of 30 piglets farrowed, 27 survived.

For three weeks in June, scientists counted the apples that fell to the orchard floor. Then the pigs were kept in part of the orchard to feed for two to three days. The apples then were counted again to see how many the pigs left behind. The hogs were very thorough -- the researchers found very few apples.

"Eighty to 90% of their food was apples, supplemented with organic corn," Koan said. "They loved the June drops -- the piglets liked them best. The hogs would lie around while the piglets would scurry from tree to tree as one group to feed."

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The area of the orchard that wasn't part of the hogs' buffet had five times the curculio damage as the grazed areas. The hogs' rooting around the apple trees also saved Koan from having to rototill around each tree to suppress weeds in the grazed organic orchard. The pigs will be grazed through the orchard once again this winter.

Dale Rozeboom, associate professor of animal science, monitored the hogs' reproduction, health and nutrition for the project. One of the major challenges with an apple diet is making sure the animals get enough protein.

"The pigs born last spring are not up to market weight yet, likely a result of plenty of exercise. Otherwise they seem to be very healthy," Rozeboom said. "We’ve only observed light numbers of parasites in collected fecal samples."

In a controlled experiment conducted at MSU, Rozeboom fed plum curculio larvae to 3-month-old pigs and collected and washed all feces to confirm that ingestion by pigs was lethal to the larvae. Of more than 250 larvae fed over a six-day period, no live plum curculio and only the remains of one dead larva were found.

"This was an encouraging first year for the project," Epstein said. "One of the issues we want to look at further is the optimal number of pigs needed per acre to control plum curculio."

As the project continues, Rozeboom will be looking at pork production-related factors, such as the types of supplements necessary for adequate weight gain and pork quality. The research is funded through a grant by the USDA Integrated Organic Program.