December 2014

VM Views: Research Supports Aquatic Label Addition For Milestone® And Capstone®

Vegetation managers would like to be able to control weeds in sensitive aquatic sites by using the effective control that Milestone® and Capstone® specialty herbicides provide. That may be possible soon.

Milestone and Capstone are both used for control of unwanted weeds, including noxious and invasive species, vines and brush. The current labels for these products allow treatment of weeds, brush and vines growing on a wide variety of use sites, including those near water, such as nonirrigation ditch banks, seasonally dry wetlands (flood plains, deltas, marshes, swamps or bogs), and transitional areas between upland and lowland sites. The labels also specify that they can be used to the water’s edge but precautions should be made to minimize spray drift into water.

An aquatic registration would allow for the additional flexibility of using Milestone and Capstone to control invasive or other weedy plants along shorelines and on banks of ponds or moving water sites, including many emerged species that grow directly in the water.

Supportive Research at a Glance
Dow AgroSciences, which developed Milestone and Capstone, funded studies to support this label addition. Field research trials were initiated in ponds and flowing water systems, and research was designed to establish edible food tolerances for fish, shellfish and crustaceans, as well as further define herbicide dissipation in water and sediment over time.

To study dissipation in ponds at test sites in Texas and Indiana, Milestone was applied at 7 fluid ounces per acre (fl. oz./A) on pond banks, with intentional overspray into adjacent water. Caged organisms, including catfish, bluegill, sunfish and freshwater clams, were collected prior to and following application. Tissue analysis provided data on the amount of Milestone® specialty herbicide in the aquatic organisms and whether residues were at levels that would harm animals consuming the organisms.

In short, results indicated that there was rapid dissipation of Milestone in all environments and provided data to establish tolerances for aquatic organisms in the study.

To study dissipation in a flowing water environment at test sites in Oregon and Florida, Milestone was applied at 7 fl. oz./A along the stream bank with intentional overspray into adjacent water.

In short, results showed that dissipation went to nonquantifiable levels or was nondetectable within the treated plots and downstream in just a few hours following application.

This data was collected and submitted to the U.S. Environmental Protection Agency for review in November 2012 to support listing aquatic uses on the labels for Milestone and Capstone. The cost of these studies — more than $500,000 — represents Dow AgroSciences’ commitment to providing vegetation management professionals with the solutions they need.

Registration will support use of these products for invasive or other weedy plant control on shorelines and on stream or river banks with a label expansion. Following approval, labels are not expected to have restrictions on swimming, fishing or livestock use of water after applications. Use will not be permitted on the inside banks of irrigation ditches or for submersed aquatic plant control. Precautions and restrictions on use of water treated with Milestone or Capstone for irrigation likely will be included on the new label. Registration is anticipated for the 2015 use season.