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Hometown U: The case of the twisted potato plants

Kathleen McCoy

Ellie Henke is a Talkeetna gardener with a problem in her beds. A weed scientist with the UAF Cooperative Extension Service and a UAA environmental chemist are working together on a solution.

Gardeners around the state might want to pay attention.

Henke's story goes like this. For four years she enjoyed robust vegetables from soils she'd enhanced with composted manure, lime, blood meal and other typical soil additions. But in 2012, as she wrote to weed scientist Dr. Steven Seefeldt, "disaster struck."

Last year's growing season began well enough, with healthy sprouts taking off indoors in commercial potting soil. But when she transplanted her fledgling flowers and vegetables into outdoor beds, something went wrong.

Her marigolds didn't flower; instead, they grew odd-shaped leaves and thick stems that looked blistered. After transplanting, her tomatoes got spindly and their leaves didn't develop. The same thing happened to her potatoes. Almost none of her peas and bush beans germinated. Carrots and beets grew slowly and failed to thrive.

Frustrated, Henke showed her crop to a fellow gardener, who recognized the cupped leaves and fiddle-necked stems as the same nightmare she'd experienced a year earlier. After researching her problem on the Internet, she had come to an hypothesis that Seefeldt says looks about right: her soil was contaminated with an herbicide used to tamp down weeds in pastures and hay fields.

 

THE SUSPECTS

The likely culprits, aminopyralid or clopyralid (sold under the brand names of Milestone and Transline), knock out broad-leaf weeds like docks and thistles without hurting hay and grasses. When domestic animals eat the grasses, herbicide residue concentrates in their manure. The manure gets sold or shared with growers, and the aminopyralid ends up in places it was never intended, like Henke's vegetable garden.

Henke and her friend had both used yak manure from a Talkeetna neighbor, who later remembered buying hay from a commercial seller in Point MacKenzie.

Seefeldt had heard this sad tale already. He'd just finished working with a Delta potato farmer who'd sprayed for noxious weeds in an area where he didn't grow any crops. Two years later, he put in potatoes, but reported that his plants grew funny. The potatoes he saved and planted the next year also had problems.

Seefeldt kicked off a study that documented the damage, proving that potatoes are susceptible to aminopyralid.

Next comes the environmental chemist's job. This summer, Dr. Patrick Tomco will test soils to determine how long aminopyralid can persist in our colder northern soils.

Aminopyralid is approved for use in Alaska by the Department of Environmental Conservation, based on studies done in temperate climates. But what works in test soils in California, Florida or Illinois may not apply in chilly Alaska, Tomco says.

The speed with which the herbicide can travel through Alaska's food chain concerns Seefeldt, Tomco and others, including Bret Burroughs of the Anchorage Soil and Water Conservation District. Despite appropriate instructions advising users to restrict use and not sell or share manure from animals that have ingested treated grasses, aminopyralid is popping up in the wrong places.

Right now aminopyralid is expensive, but once its patent expires, it will be cheap. Tomco worries that its use will only spread.

Farmers, parks managers and invasive weed specialists all say aminopyralid is effective against troublesome invaders like orange hawkweed and Canadian thistle. If used correctly, it can help protect native plants, an important environmental concern.

Tomco got seed moneyfrom UAA to prep some plots in Delta Junction and Palmer, which he'll spray this summer with aminopyralid, and then sample the soil to measure the compound's degradation. Sunlight and microbes are thought to degrade it; he hopes to determine which of the two processes causes the most degradation.

Another question is how far aminopyralid contamination has spread. Tomco's goal is to patent a method for measuring residue in soil, water or manure. An ideal solution would be a simple dipstick that farmers and citizen scientists could jab into soil and quickly determine the level of herbicide.

His bigger goal is to use data from these early studies to persuade large national funders to finance a look at Alaska's cold climate and how it may inhibit the degradation of chemical compounds like aminopyralid.

 

RESEARCH UNDERWAY

Palmer-born Tomco returned to Alaska two years ago after earning his doctorate in environmental chemistry from the University of California at Davis. He teaches organic chemistry at UAA and looks for ways to develop research.

In Alaska, he hasn't had to look far. Already he's talking to the city about testing herbicides on Elodea, an invasive aquarium plant that seems to be taking over Sand Lake. He's growing vats of it in the lab, getting ready to test herbicidal applications. The concern with Elodea is that floatplanes could easily spread noxious mats of it to lakes throughout Alaska.

And, of course, there are invasive northern pike that threaten to decimate salmon populations.

"I'll be talking to fish and game about rotenone, a piscicide for the pike," Tomco said.

 

Kathleen McCoy is an electronic media specialist at UAA, where she highlights campus life through social and online media.

 


Kathleen McCoy
Hometown U