By SHELLY STRAUTZ-SPRINGBORN
Michigan Correspondent STANTON, Mich. — Potatoes growing independently in fields of corn, soybeans and other crops, can harbor diseases that could adversely impact the area’s potato crop.
Willie Kirk, extension specialist for potato diseases at Michigan State University, said this year’s crop of “volunteer potatoes” is fairly normal. “When I say fairly normal, I mean it’s really bad. It’s a problem we see every year,” Kirk said.
Montcalm County is Michigan’s largest potato-producing county, growing over 16,000 acres of potatoes primarily for the potato chip market.
The volunteer crop results from potato tubers that survive the winter and eventually begin growing somewhere that a farmer doesn’t intend for them to be.
“The main thing is waste potatoes,” Kirk said. “Potatoes are returned to a field for a couple of reasons. If they’re outside of the range desirable, they may be spread back on a field or if they are too small and they slip through the harvesting equipment.
“When they are returned to the ground, the machinery tends to push the tubers back into the ground. That volunteer tuber has to be in the soil and survive the winter,” he said.
Kirk said there are several factors that play into overwintering of the tubers.
“Insulation can come from being deep enough in the soil and snow cover also acts as an insulator,” he said.
Kirk also said a cover crop planted to reduce soil erosion also could provide enough insulation to protect the tubers.
“If the tubers were left on the surface there’s a fair possibility that they would die over the winter,” he said.
Other factors, Kirk said, are global warming and drought-tolerant potato varieties that are more temperature tolerant. “People don’t like to hear that, but due to global warming it doesn’t necessarily get cold enough to kill the spores” that carry disease, he said.
“Some varieties are bred to be fairly drought tolerant and they’re less sensitive to changes with temperature, too.” The biggest potential problem caused by volunteer potatoes is the risk of harboring diseases that can infect the area’s potato crop.
“Early blight and late blight are the most common,” Kirk said. “But, other diseases also can stay in the soil and continue a reservoir of disease in the fields. The most important thing is that it can initiate an epidemic of disease because these potatoes are usually located in fields not being treated with a fungicide.”
Lisa Ulrich-Johnson, whose family grows primarily corn, soybeans
and potatoes, on about 2,000 acres near Lakeview, said potatoes growing outside of properly managed potato fields are a concern for growers.
“Untreated potatoes give the potato bugs something to feed on. That’s not good because they’re there,” she said.
Other disease issues, such as blight, are cause for concern too. While Johnson said growers already treat their potatoes with fungicides she said that long-term disease issues must be managed.
“Researchers tell us that they can harbor disease. That’s a concern for us.
“But, if there’s blight around to be had, more than likely the fact that there are unprotected potatoes may or may not make it likely that you’re going to get blight,” she said. “If it’s here I’m not sure that it’s going to make our potatoes more susceptible because we spray for it anyway.
But, the Johnsons don’t take any unnecessary chances with their cull potatoes. Instead of dumping them on fields, any waste potatoes they have are used for animal consumption.
“The best way to dispose of them is to feed them to our cattle. That keeps them out of the fields,” she said. This farm news was published in the June 13, 2007 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee. |
