Archive for the ‘Herbicides’ Category

European agency does not classify glyphosate as a carcinogen

The European Chemicals Agency’s Committee for Risk Assessment has agreed to maintain the current harmonised classification of glyphosate as a substance causing serious eye damage and being toxic to aquatic life with long-lasting effects.

But it concluded that the available scientific evidence did not meet the criteria to classify glyphosate as a carcinogen, as a mutagen or as toxic for reproduction.

The committee said it has assessed all the scientific data, including any scientifically relevant information received during the public consultation in summer 2016.

Its  classification is based solely on the hazardous properties of the substance. It does not take into account the likelihood of exposure to the substance and therefore does not address the risks of exposure.

The Science Media Centre has posted two expert opinions from Britain (HERE) on the ruling.

Prof Jan Hengstler, Head of the Department of Toxicology / Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADO), TU Dortmund, Dortmund, comments:

“The European Chemicals Agency (ECHA) Committee on Risk Assessment (RAC) has concluded that the substance glyphosate does not meet the criteria to be classified as a carcinogen, as a mutagen or as toxic for reproduction. This conclusion is scientifically justified. Both the available long-term studies in rats and mice as well as epidemiological data do not justify the conclusion that glyphosate is carcinogenic or mutagenic. Under current conditions of use of glyphosate there is no increased cancer risk for humans. Compared to other herbicides, a relatively large number of studies is available on the substance glyphosate, so that a comparatively good assessment with regard to the carcinogenic risk is possible. The conclusion of the ECHA is not surprising, since no new studies were available compared to earlier evaluations.”

Prof Alan Boobis, Professor of Biochemical Pharmacology, Imperial College London, comments:

“ECHA are to be congratulated on their critical evaluation of a large and complex dataset on glyphosate. They have concluded that the totality of the evidence is that glyphosate should not be considered a human carcinogen. It is important that such objective, independent and comprehensive assessments are available to help policy makers in reaching evidence-based decisions”

Application to extend use of herbicide Callisto approved

The Environmental Protection Authority has approved an application from Syngenta Crop Protection to extend the use of the herbicide Callisto. This is a previously approved herbicide, which contains the active ingredient mesotrione.

The application sought to change the application rate and frequency of Callisto to allow it to be effective when used on turf. This has been approved with controls. There is no change to the application method.

The application was open for public submissions and three submissions were received. No hearing was held for this application.

Applications and Assessment General Manager Sarah Gardner said the EPA decision-making committee assessed the benefits, risks and costs associated with the herbicide during the various stages of its life cycle.

Controls are conditions or rules imposed on the approval that restrict the use of the substance to ensure people and the environment are protected properly when it is used, for example controls might require users to wear protective masks or gloves when spraying.

In this case the revised controls include the wearing of personal protective equipment, setting of a maximum application rate and minimum re-application interval, the type of spray nozzle that must be used and imposition of buffer zones downwind of water bodies and non-target plants. These controls must be set out on the product label.

 

Let us spray – but the time of day is important for a greater impact

Some herbicides are more effective when applied at noon compared to early morning or late evening applications, according to data from the University of Tennessee Institute of Agriculture.

The study evaluated three protoporphyrinogen oxidase (PPO) herbicides applied to glyphosate-resistant Palmer amaranth in soybean plots at sunrise, noon and sunset. After 14 days, the noon applications on average performed 15 to 20 per cent better than the sunrise applications. The noon applications outperformed the sunset applications by an average of approximately 10 per cent.

“We’re definitely getting better control when these herbicides are applied in the middle part of the day,” says Garret Montgomery, lead author and doctoral student with UT’s Department of Plant Sciences.

PPO herbicides work by inhibiting an enzyme involved in chlorophyll production. Researchers explain that this family of herbicides is significant to agricultural producers as it’s the only post-emergence mode of action available for controlling glyphosate-resistant weeds in glyphosate-tolerant soybeans. Soybeans are Tennessee’s top crop.

The study’s findings were consistent with earlier research performed by UTIA and other universities on herbicides with different modes of action, like glufosinate. In these earlier studies, tested herbicides were also most effective when applied at midday.

“Being able to determine the optimal time of day to apply herbicides is important for several reasons,” says Larry Steckel, row crop weed specialist with UTIA. “Perhaps most significantly, it can reduce the number of times farmers must apply these herbicides as they work to produce a crop. Weeds that are injured but not killed from a previous application will only get more difficult and expensive to remove.”

“Using our herbicides as efficiently as possible could actually reduce the rate at which weeds evolve herbicide resistance,” Steckel continues. “So this study has long-term implications for weed management.”

The study was conducted at the West Tennessee AgResearch and Education Center in Jackson, Tennessee, as well as the Delta Research and Extension Center in Stoneville, Mississippi.

Montgomery presented the study last month at the Weed Science Society of America and Southern Weed Science Society annual meeting in San Juan, Puerto Rico.

The paper is titled “Environmental Influences and Time of Day Effects on PPO-Inhibiting Herbicides.” Additional co-authors were Steckel along with B.H. Lawrence, H.M. Edwards and J.A. Bond of Mississippi State University. The study was supported by Cotton Incorporated, the United Soybean Board and the National Association of Conservation Districts.

See visual representation of study through time lapse photography here​.

 

Submissions sought on modified reassessment for herbicide

The Environmental Protection Authority is calling for submissions on a modified reassessment of the herbicide Callisto. This is an already approved herbicide, which contains the active ingredient mesotrine.

The current approval for Callisto has restrictions on the rate at which the product is applied and the number of applications. The applicant, Syngenta Crop Protection, is seeking to increase the application rate and frequency, and extend the use of the substance to include turf. There would be no change to the application method.

If approved, the substance would be marketed as Tenacity Turf Herbicide.

The application is being notified due to application changes.

The submission period for this application started on 28 April and will close at 5pm on 10 June.

Further information on submissions and the hearing process can be found here.

The EPA’s role is to decide on applications under the Hazardous Substances and New Organisms Act to import and manufacture hazardous substances. It puts controls in place to manage the risks of hazardous substances to safeguard people and the environment.