MSMA UPDATE FOR TURFGRASS SOD PRODUCTION
By Casey Reynolds, PhD
MSMA is a broad-spectrum organic arsenical herbicide that has been registered for use in the United States since 1964. (MSMA is an acronym for MonoSodium Methane Arsonate.) MSMA has been used for many years in commercial and residential lawn care; parks and athletic fields; golf courses; bluegrass, fescue and ryegrass grown for seed; as well as cotton; non-bearing fruit and nuts; citrus, bearing and non-bearing; forestry; drainage ditch banks; railroad, pipeline and utility rights-of-way; fence rows; storage yards; and similar non-crop areas. MSMA is a Group 17 post-emergent herbicide that is labeled for control of many annual and perennial weed species such as crabgrass, dallisgrass, foxtails, johnsongrass, goosegrass, nutsedge, and others. It has been sold under many different trade names and until 2009 was labeled for all the above-mentioned uses.
In 1983, the registrants of MSMA formed the Methane Arsonic Acid Research Task Force (Task Force) to conduct scientific studies in response to requests for information from the U.S. Environmental Protection Agency (EPA). Despite the fact that those studies indicated no concern for risk to human health or the environment from MSMA use, in 2006, the EPA proposed the cancellation of all the uses of MSMA. Te proposed ban was based on their concern that the use of MSMA may result in an increase of inorganic arsenic in soil.
Te EPA first announced its decision to terminate uses of organic arsenicals on July 8, 2006. In 2009, after three years of negotiations, the Task Force reached an agreement with EPA for the continued registration of several uses of MSMA and the cancellation of the other organic arsenical products. Te agreement retained the permanent registration for MSMA use on cotton. Tree turfgrass uses were conditionally registered—turfgrass production, golf courses, and highway rights-of-way (ROW). All other uses were canceled. Florida also was deleted from the label for turfgrass uses.
Te condition of the registration for the turfgrass uses was the submission of additional scientific data by the Task Force demonstrating the safety of the product, as well as no concern from inorganic arsenic resulting from the use of MSMA. Te 2009 agreement also stipulated that EPA would conduct a review of the submitted scientific data. Note: In 2009, the Task Force changed its name to the Organic Arsenical Products Task Force (OAPTF).
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Te required information was submitted to EPA in 2012. However, ten years after the agreement was signed, EPA has not completed the agreed upon review of the accumulating scientific data that would enable a realistic assessment of whether there is a potential risk to human health or the environment from the use of MSMA.
Te lack of broad spectrum, economically acceptable, alternative products, combined with the emergence of several new problem-weed species and an increase in resistance of weeds to other herbicides, makes a broader availability of MSMA of increasing importance.
In response to those needs and requests from users, the Task Force is planning to submit an application to the EPA in the coming months under the Pesticide Registration Improvement Act (PRIA). Tis application would seek to make the current turfgrass production uses of MSMA permanent, to restore uses canceled in 2009 (e.g., athletic fields, parks, lawn care by licensed applicators), and to amend the application restrictions for some of the current uses. In response to requests from users, the Task Force will potentially seek to add Florida back to the label for golf courses and turfgrass production. Te PRIA application is also intended to prompt EPA to conduct the risk assessment of MSMA called for in the 2009 agreement.
An important element in making the case to EPA will be continued support from users to demonstrate the critical need for MSMA. TPI is working with the Task Force (OAPTF) to construct comments for submission. TPI also met with the EPA in Washington, D.C., on May 16, 2019, to discuss with them how important this product is in turfgrass sod production. Our speaking points during that meeting included the following:
TPI Turf News July/August 2019
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