Informed use of manure as a garden fertilizer

Livestock manure is a natural garden fertilizer and soil conditioner, yet depending upon the source it can contain contaminants that include weed seeds, metals, salts, microorganisms and herbicide residues. Herbicide residue in manure can harm sensitive plants, such as potatoes or beans in gardens. Appropriate user directions and precautions have been included on labels where this potential exists for that herbicide manufactured by Dow AgroSciences. This website was created to provide information that will help gardeners and others be better informed about the use of manure or compost to fertilize gardens.

There have been some reports of herbicide damage to sensitive crops, such as potatoes and beans in gardens following use of manure as a garden fertilizer. While this could be due to a number of herbicide products, the information on this website addresses manure from farm animals or horses fed on pastures or hay treated with aminopyralid herbicides.

What is aminopyralid?

Aminopyralid is an important active ingredient in herbicides used in the pasture, rangeland, small grains and vegetation management market segments. Aminopyralid was accepted for review by the U.S. Environmental Protection Agency (EPA) under its Reduced Risk Pesticide Initiative  and met all requirements for the registration of an herbicide in the United States.

The herbicide is important for several reasons. It controls numerous noxious, poisonous and invasive weeds at significantly lower use rates in comparison with commonly used herbicides. It provides superior control of a number of difficult-to-control broadleaf weeds and woody weeds. And it has an excellent health, worker safety and environmental profile.

Herbicides or Noxious and Invasive Weeds?

Aminopyralid-based herbicides were developed to help farmers and ranchers control and eliminate a number of troublesome and potentially dangerous perennial broadleaf weeds in fields and pastures, and to help vegetation managers control difficult-to-control weeds, invasive plants and some woody weeds along and under utility lines, along roadsides and similar sites. Aminopyralid is especially effective against difficult-to-control weeds, such as Canada thistle, musk thistle, tropical soda apple, spotted knapweed, diffuse knapweed, yellow star thistle and Russian knapweed.

Although some people may question the use of herbicides, there is no question that the weeds they eliminate are a concern. Aminopyralid herbicides control broadleaf noxious, poisonous and invasive broadleaf weeds and some woody weeds without damaging grasses. By controlling such problem vegetation, aminopyralid helps re-establish and preserve natural areas and wildlife habitat. It also can improve grassland and small grains productivity, enhance roadside visibility and safety, ensure uninterrupted electrical power and natural gas utilities, reduce mechanical maintenance needs and reduce fire hazard.

What is the chance that manure contains aminopyralid?

Reports of alleged garden or landscape plant damage due to aminopyralid have been rare in the United States. It is possible that manure from cattle or horses may contain aminopyralid, but only if aminopyralid was used to control weeds on pastures where the animals grazed or in hay taken from such pastures, and aminopyralid label directions regarding management of manure were not followed.

Manure from hogs should not contain aminopyralid as they do not feed on grasses or hay.

When it is used properly, is aminopyralid dangerous?

No. Aminopyralid has an excellent environmental profile, and the U.S. EPA, along with regulatory agencies in other countries, has determined that it does not pose an unreasonable risk to human or animal health or the environment when used in accordance with label directions.

What is Dow AgroSciences doing?

Dow AgroSciences is focusing on education because understanding and adhering to label directions will prevent aminopyralid from getting into garden manure, compost or mulch. The ongoing Dow AgroSciences product stewardship program is educating customers — distributors, retailers, custom applicators, end-users and key centers of influence, such as state Departments of Transportation, university extension specialists and others — to abide by all label directions and precautions. And because risk of damage to non-target vegetation varies due to market considerations, product stewardship addresses the specific needs of the crop, rangeland and pasture, and vegetation management markets as necessary. The goal is to prevent damage to gardens by increasing awareness and understanding of label directions, and proper manure and hay management practices.