We are a USDA certified Organic ornamental nursery grower and landscaper. As far as we know, the first and only landscaper/grower in the US to qualify. (Lot's of hoops.) So we practice what we preach. Kevin my comments were not aimed at you, just a question about the thread. Sorry if I offended.
OMRI= Organic Materials Review Institute is the only USDA approved list of Organic products and is the standard for whether or not a product is considered and approved for organic use. Here's the link to the list:
My source on the longer than rated effects of Roundup and similar products is the research published by Beyond Pesticides.org a non-profit consortium of environmental scientists. Their database is at this link:
As I understand it, Roundup in ideal circumstances and applied at minimum necessary rates, has a 10-14 day lifespan when exposed to the sun and not washed off by rain, dew or irrigation. If however it does wash off or is covered up by landscape fabric or mulch (often used to kill vegetation before mulch is installed) and even on debris or tools,clothes, toys that was sprayed and not exposed to UV radiation the active ingredient glyphosate can stay active for months. This is the direct cause of problems with Learning Behavior (Porter), Non-Hodgkin’s Lymphoma and Pesticides allergies, (American Cancer Society).
I visit several hundred wholesale nurseries a year as a buyer looking for pesticide free liner and specimen stock and unfortunately at the majority of Nursery operations I visit, the chemical usage violates OMRI and EPA standards. The user/applicators (often migrants) are poorly trained, if trained at all, and there is little if any documentation of what or how much get's sprayed where or when. It get's even worse when you visit large farm operations and see how they handle chemicals. (we have a 500+ acre conventional farm in Va.) If you confront the management of most of these operations or discuss the problems with the MFG's reps they talk the talk but fail to follow through. The result is that over 90% of the rural water supplies of the US are contaminated with varying degrees of chemicals like Roundup or Atrazine which are being used in the tens of thousands of tons. I talked a few weeks ago with a VP of Asplundh Tree Experts and he described their (hopefully) former national practice of saving the used motor oil from their trucks and mixing it with Arsenal, Roundup and other brush weed/killers and spraying power line rights-of-way all over the US through private properties, over water, anywhere the Power lines ran with no worker protections or public warning or knowledge of this toxic soup they were hired to spray by AEP, TVA and other major Power companies. It's a wonder they haven't been sued!
As more lawn, landscape and Arborist professionals make the connection and the commitment to be Organic and educate their customers as to the value of best Organic practices we can change our industry and the country. The result of Roundup use is not just a longterm chemical risk. It has unintended habitat consequences!
Dr. Paula Shrewsberry at the University of Maryland is currently conducting trials on the best ways to grow ornamental landscapes using Organic methods. One of her early findings (as reported last year at a UK sponsored IEP Seminar on Pesticide Practices in Shelbyville KY) was that if Roundup is used in field growing, the unintended consequence was that the host habitat for good bugs was reduced or eliminated, leaving the bad bugs a field day on the landscape stock. In Lake Tree Farms field and landscape trials on our own farms and customer's jobs, we have found that their is little or no need of Roundup with good management, careful landscape planning, and some good old fashioned weed pulling. No we don't solve every problem (wire grass still confounds us) but with time, alternative non-toxic natural solutions will be found if we all share our experience for the benefit of the public and the environment we all live in.