The hidden side effects of using
chemical weed killers

Andy Crossland
Adams County Master Gardener

A few days ago I got a call from someone wanted to know about a weed killer that he had read about in newspaper.

Before I tell you the name I have to tell you that my mentioning the chemical, or the web search engine that I used to research it are only the opinions of this old dirt digger and do not represent any official Penn State University recommendation or condemnation of anything. Though you will see that Penn State is one of the first scientific bodies that had occasion to find the problem.

The caller said that the chemical was called clopyralid. I told him that I wasn't familiar with it, but would look it up and see what I could find out for him. He said that he would mail me a copy of the article. After dinner I turned on the Internet and went to " ". I typed in clopyralid. Looked like I would not have to wait for the snail mail arrival of the article, because in less than 5 seconds I had links to 4700 articles that were on the web. I started to browse the articles. One of the first was from Penn State. It seems that they started a compost program and at first used their resulting brown gold only in the ornamental beds.

The compost was first tried in the vegetable trial beds on the bell peppers. They were trying to determine the correct amounts of compost to apply. About 4 weeks after the peppers were transplanted from the greenhouse to the trial beds they began to show signs of what looked like 2,4,D herbicide contamination. To save space look up the results of this investigation on line and see why once it was determined that the compost did it, they are still putting it on the trial beds. I found a 30 some page paper from the manufacturer that broke down all the tests and results and made the stuff seem as safe as rain.

Then I came to the " The Journal of Pesticide Reform " page. It said a lot of contradictory things. These people (the Manufacturer and the detractors) all talk about half-life of the chemical. Half-life? I thought that referred to nuclear degradation. Chemical degradation also, it seems is expressed in this manner. The findings from this organization were very different than that of the people who make it. Fetal skeletal deformities in ducks, rats, mice. Water solubility was another area where the opinions differed.

The chemical comes in three formulations. Two of the bases seem to cause very bad and sometimes permanent vision problems in humans. The compost counsel said that the occurrence of clopyralid in compost could not be controlled by the commercial compost operation. They took the stand that there could be contamination in compost for 14 months or more. The revised labeling on one of the brand names of clopyralid said that compost containing treated materials should not be used in the same year as the treatment was applied. This is not feasible. Some compost facilities make the transition from waste to compost in a row method and this takes from 2 to 6 months. There are faster ways.

Tumbler composters make this miracle happen in a whole lot less time than that. The main homeowner use of clopyralid is the elimination of broadleaf weeds in turf grass. If you compost at home do your grass clippings go into your compost? If one homeowner sends treated grass clippings to the commercial compost plant will that be enough to make the whole batch lethal to the garden plants it is put on.

Penn State's peppers were affected not by composted grass as a main course for the composters, but by the incidental grass that was sucked up when the leaves were vacuumed up. As most weed killer is applied in the spring, and most leaves are vacuumed in the fall this make me wonder about that half-live. Would you not like to roll in the grass, walk down a power line, or have your pet frolic in the beautiful, weed-free front yard of your home, with your children. What is used on the parks and ball fields in our area? How about where we travel? I know that all sides of a question slant issues at times, and that to have any adverse effects you would probably have to dive into a bath tub full of the stuff, or would you? What are you to do?

As a home composter, you can control what you put into your own version of brown gold. Read labels. Become an informed consumer. Research is so easy now that we have the Internet. No computer you say, go to the Adams County Library. They will help you find the pages you need. Ask a Master Gardener. We exist to educate the people of our home counties. Find out which weeds are edible and throw a dinner party. Learn to pull weeds and if the scale of your operation makes that impractical read, understand and follow the application rates and listed uses on the package label. More is not better.

I do not know who is right and who is wrong in this debate. No matter what the truth is, higher prices or chemical poisoning will mean that the ultimate loser is us.

We come from the Earth. We return to the Earth. In between, we garden. You meet the nicest people in the garden. See you in the garden.

Read other articles on ecological gardening & native plants

Read other articles on lawn care & weed control

Read other articles by Andy Crossland