Using a Section 18 label granted in selected states for use from April until August 2012, Clemson University Researcher Mike Marshall used Brake as an effective herbicide against Palmer amaranth in cotton, providing a potential new tool for growers in the their ongoing battles against pigweed.

Over-use of PPO inhibitor herbicides in areas with high levels of glyphosate resistant cotton is a big concern for cotton growers in some parts of the Upper Southeast.

In many areas of the Southeast these popular herbicides are widely used in other crops that are grown in rotation with cotton.

The growing number of herbicide resistant Palmer Amaranth (pigweed) populations, combined with the fear that resistance problems may occur with over-use of glufosinate and other herbicide families without resistance problems, leaves growers with few herbicide options for over-all weed protection in cotton.

This scenario further accentuates the need for new herbicides with different modes of action, especially for control of Palmer amaranth.

“The big advantage for Brake is that it could be a really good rotational material for Reflex and Valor, two PPO inhibitors that are widely used for weed control in cotton,” Marshall says.

Brake, a product of SePRO Corporation, Carmel, Ind., was given a Section 18 label for use in 11 South Carolina counties in 2012, but the label came with some specific restrictions. The label states, “Brake may persist in the soil past the cotton growing season. To avoid difficulties in establishing rotational crops, the following precautions must be followed:”

• Do not make more than two consecutive applications of Brake. After the second application, use an alternative herbicide effective in controlling the weeds of concern.

Consult your agricultural dealer, consultant, applicator, and/or appropriate state agricultural Extension service representative for specific alternative cultural practices or herbicide recommendations available in your area.

• Apply prior to planting or prior to emergence of cotton;

• Only apply in fields where cotton will be planted both in the year of application, and in the year following application, and not rotated with another crop, unless the following crop rotational restrictions are followed for 18 months — Do not plant grain sorghum, sugar beet, tomatoes and other Solanaceae family of crops for at least 18 months after the last Brake application;

In the Clemson studies, done at the Edisto Agricultural Research and Extension Center in Blackville, S.C., Phytogen 499 was used primarily because it has built in tolerance to both glufosinate and glyphosate, Marshall explains.