The Woodland Trust, the UK's largest tree planting charity, claims to have conservation and biodiversity aims but is using chemical weed-killers. Such weed killers can result in "superweeds" that are resistant to current herbicides, which will require stronger doses or more toxic compounds in the future to control them.

The Trust admits using MCPA and Glyphosate.

This is what the experts say:

  1. Glyphosate treatment has reduced populations of beneficial insects, birds, and small mammals by destroying vegetation on which they depend for food and shelter. In laboratory tests, glyphosate increased plants' susceptibility to disease and reduced the growth of nitrogen-fixing bacteria.
    Source: Caroline Cox, Scientist, Nortwest Coalition for Alternatives to Pesticides. www.pesticide.org/glyphosate.pdf
  2. The University of Nebraska at Lincoln (UNL) announced their weed scientists had confirmed the presence of the first glyphosate-resistant weed in the Good Life State. They said it reinforced the need for farmers to implement integrated weed resistant management (IRWM) strategies.

    According to a UNL press release, it took a year of testing to determine marestail in Nebraska, also known as horseweed, is resistant to glyphosate. The release said it's the first glyphosate-resistant weed to be confirmed in the state.

    Steven Knezevic, integrated weed management specialist at UNL's Haskell Agricultural Laboratory said widespread use of glyphosate herbicide, developed by Monsanto Company under the Roundup Ready brand, has resulted in selection pressure on weed populations since its launch a decade ago.

    "Prior to the introduction of glyphosate-tolerant crops only a few weed species, ryegrass and goosegrass, had developed resistance worldwide," Knezevic said in the release. "However, the number of glyphosate-resistant weeds tripled in just over eight years of repeated glyphosate use due to the introduction of Roundup Ready crops."
  3. While marked changes in populations of birds and small mammals have been documented following glyphosate application, these changes are attributed to alterations in habitat, vegetation cover, and food supply resulting from the herbicide's intended effects.
    Source: World Health Organisation.
    http://www.who.int/dsa/cat98/ch emtox8.htm#Glyphosate (now only available to view on archive.org due to site changes at who.int)
  4. Birds: Glyphosate is moderately toxic to birds. In addition to direct effects, it may have indirect effects because it kills plants, therefore it may cause dramatic changes in the structure of the plant community, with a detrimental impact on birds, because they depend on the plants for food, protection, and nesting. This has been documented in studies of the populations exposed. Small mammals: In field studies, populations of small mammals have also been affected by glyphosate, by death of the vegetation that they or their prey use for food or protection.
    Source: Dr Elsa Nivia
    http://www.usfumigation.org/Nov PressConfSpeakers/ElsaNivia/ElsaNivia.htm (now only available to view on archive.org due to site changes at usfumigation.org)