Weed invades northwest Ohio fields

SALEM, Ohio – Implements moving field to field are likely to blame for the spread of a noxious weed in Ohio.

Weed scientists are asking farmers’ help in tracking the weed’s location and density across the state.

First sighting. Apple of Peru, or Nicandra physalodes, also known as shoo-fly, was first encountered a year ago in Seneca and Sandusky counties.

Since then, it’s spread to an estimated 2,000 acres in northwestern Ohio, according to Ohio State Extension weed scientist Joel Felix.

The weed may have have put down roots across the state, but has yet to be identified.

Spreading. When the plant was identified in a Seneca County pepper field a year ago, one portion of the field had density of 12 plants per square yard.

Some of those plants were 6 feet tall, reports said.

Though the weed had previously been found only in vegetable plots, preliminary reports in early August identified a weed may have rooted in a wheat field near Upper Sandusky.

Felix said he had yet to identify the weed.

Origin. Apple of Peru is believed to have spread to Ohio from peanut and vegetable crops in either Georgia or North Carolina, but no transfer method has been determined, Felix said.

Felix also indicated the plant is used for decorative and medicinal purposes, and could have made its way to Ohio through seed trades.

The weed is also a problem in the soybean fields of Brazil and in corn in Australia and Japan.

Waiting to attack. According to Felix, the weed has been lingering in the region for five years.

Scientists believe each plant produces thousands of seeds that lie dormant in the ground for years, Felix said.

“Then it seems to take off one year when the crop isn’t so good,” he said.

Scientists also said the seeds germinate and the plant produces more seeds after herbicide applications are complete, rendering traditional weed-fighters useless.

Getting hold. Scientists are itching to get hold of the weed they initially thought wasn’t a big problem.

Researchers in Wooster have received grants from the North Central Pest Management Center at Michigan State University and from the Ohio Fruit and Vegetable Research and Development Program to test herbicides on apple of Peru.

Cause for alarm. What alarms scientists most is the weed’s herbicide resistance.

Apple of Peru survived and prospered in a field that had been in corn and Roundup Ready soybeans for the previous 10 years.

The pepper crop had been sprayed with Dual Magnum and Command before planting, cultivated three times and hand weeded once. Apple of Peru still showed up.

Controlled tests have shown why the weed survived. In the greenhouse, it was completely tolerant of field rates of Dual Magnum and Command.

It also tolerated several other herbicides including ALS-inhibitors that are used on soybeans and vegetables.

Felix’s research shows Roundup and Syngenta’s Callisto can kill apple of Peru, but herbicides used regularly and safely in vegetable crops aren’t getting the job done.

“About all we can do is pull [the weed] before it sets new seeds. At this stage, there’s nothing we can do chemical-wise to control it,” in vegetables, he said.

Comparison. Scientists are also comparing the weed with other species in the Solanaceae family, such as eastern black nightshade.

Apple of Peru grows faster than nightshade, indicating it will compete with crops and cause significant yield losses.

Scientists are hoping to get rid of this weed as quickly as it’s appeared, but that seems unlikely, according to Felix.

Two of the most serious weed problems in the Midwest today – giant foxtail and velvetleaf – were uncommon plants restricted to waste areas only 30 to 50 years ago.

Because the weeds weren’t dealt with then, they’ve grown to become a widespread pest today.

“My justified fear is that apple of Peru turns out to be more like velvetleaf, giant ragweed and giant foxtail, species that 30 to 40 years ago, many farmers thought were just other weeds,” said Douglas Doohan, an extension weed scientist.

“The apple of Peru infestation may yet be small enough that spread to other areas may be prevented and present infestations eradicated if the industry acts quickly.”

Scout to identify. Scientists are asking farmers to scout fields in August and September, when the plant is most visible, and report any suspected infestations to help plan containment and eradication schemes.

During August, it is easily identified by its light blue flowers and lantern-shaped seed-pods.

Shirt-pocket laminated identification cards are available from Felix by calling 330-202-3591.

(Reporter Andrea Myers welcomes reader feedback by phone at 1-800-837-3419, ext. 22, or by e-mail at amyers@farmanddairy.com.)