Herbicides Where You Didn't Expect Them

New meaning to knowing your shit...........

Gardeners warned about herbicides in manure
By Carrie Ann Knauer, Times Staff Writer	Friday, March 13, 2009
Ken Koons/Staff Photo Diane Brown plants lettuce seeds at the Carroll County Farm Museum in Westminster Thursday morning. Last year, many of the plants at the Farm Museum died, and the cause has been traced to herbicide in composted horse manure. Last year when the pea plants started curling up and withering, gardeners at the Carroll County Farm Museum weren't sure what was causing the problem. They replanted the peas four times, said Pat Brodowski, plant historian for the museum, carefully trying to regrow what is traditionally a part of the museum's heirloom garden exhibiting vegetables grown in different centuries. But the peas kept dying. And the tomatoes. And the peppers. "It was a big mystery," said Betty Francies, a master gardener who helped work in the heirloom garden last year. "You go through the reasons, you call the experts, but you don't know [why it's happening]." The one thing that they did differently last year in the garden beds that were affected was use composted horse manure, Brodowski said. Manure is a common additive to garden beds to help improve the organic matter content in the soil and bring in some nutrients. But this was the first time they had used horse manure, and it made all the difference, Brodowski said. Steve Allgeier and Bryan Butler, of the Maryland Cooperative Extension office in Carroll, looked at the garden and tried to help. Having read about similar problems happening across the country and in the United Kingdom, they arranged for a representative of Dow, one of the world's largest chemical companies, to test the soil to see if one of their herbicides was causing the problem. "Their end result was that it was not their product," Brodowski said, but the gardeners never got a definitive answer on what it was.

Butler said he's done some research of the problem, which has been seen in other gardens in Carroll and across the country that used horse manure as a garden soil additive.

Through reading about cases of garden die-off in the United Kingdom, Butler said he believes the local problems come from two new herbicides with the ingredient aminopyralid, sold under the names ForeFront and Milestone. These products are used in commercial agriculture to kill broad-leaf weeds such as thistle, which are a problem in pasture fields.

These products are remarkable because they can be used on a field and grazing animals can go right back on the field, without any waiting time, Butler said. The products pose no threat to the animals, he said. However, the herbicide is not broken down in the animals' stomachs and remains an active herbicide.

What goes into the horse or cow comes back out, he said, and it remains an active weedkiller, even in manure form.

"They're herbicides, and they're going to act like herbicides," Butler said.

For the most part, this wouldn't be a problem, Butler said, except that horse manure is sometimes passed around from horse owners to gardeners. Even horse owners who buy their hay at an auction wouldn't know whether it is likely to have the herbicide in it, Butler said.

Butler said he believes that in the best-case scenario, composting the horse manure with these herbicides at the perfect conditions should allow the herbicides to break down in about 18 months. Left on its own, however, the herbicides could remain active for up to four years.

"Eventually the manure would be safe again," he said.

Brodowski said the horse manure came from a master gardener from Carroll with a horse farm connection. Several people used it in their gardens, Brodowski said, and all had the same problems with plants dying.

Brodowski said she and the master gardeners have taken samples from different areas of the contaminated garden beds and started growing peas indoors to see what they can expect this year. Fifteen days into the experiment, the peas are showing some curling on the leaves, but it's less damage than she expected, she said.

"We'll wait another week and see if they die," she said.

In the meantime, this year they'll be planting grain crops in the affected beds instead of the vegetable families that they saw affected last year: legumes, tomatoes, peppers and beets. They also had a student do some experiments with it in the fall, and found that even low-maintenance flowers like zinnias and marigolds were affected, Brodowski said.

While there is no evidence that vegetables tainted by the herbicide would be harmful to humans, the Farm Museum doesn't want to take any chances, Brodowski said.

The heirloom tomatoes, which have always been a focal point of the garden and the source for the annual heirloom tomato tasting day, will instead be grown at the homes of master gardeners this year.

Butler said he is warning vegetable gardeners to be cautious about accepting any horse manure this year unless it is from someone who can confirm that these herbicides weren't used on the hay or pasture.

"If it's not properly composted, you're bringing in a problem, and it may be a problem next year, too," Butler said.

Reach staff writer Carrie Ann Knauer at 410-857-7874 or carrie.knauer@carrollcountytimes.com.

More about aminopyralid

Aminopyralid is a reduce- risk herbicide that provides reliable control of a broad spectrum of difficult-to control noxious weeds and invasive plants on rangeland and pastures, rights-of-way and wildlife habitat areas.

Aminopyralid is particularly effective for the control of tropical soda apple, musk thistle, Canada thistle, spotted knapweed, diffuse knapweed, yellow star thistle and Russian knapweed.

Aminopyralid has a favorable human health toxicity profile when compared to the registered alternatives for these use sites and will be applied at a lower rate. Its residual action should alleviate the need for repeat applications, resulting in a reduction in the amount of herbicides applied to the environment for the control of these weeds.

Source: U.S. Environmental Protection Agency Pesticide Fact Sheet

Suspected culprits

- Have no grazing restrictions for any type of livestock, including lactating dairy animals, beef cattle, sheep, goats and horses.

- Are not federally restricted-use pesticides, though some states require an individual to be licensed if involved in the recommendation, handling or application of any pesticide.

Source: www.dowagro.com