There have been a number of calls recently enquiring about the herbicide Brake which is being used on some limited cotton acres for Palmer amaranth control in South Carolina. Reports from cotton growers in that state indicate that Brake applied pre plant has provided very good residual Palmer amaranth control this spring. This would concur with the research we conducted at Jackson this year. So what is Brake and where do we go from here with it?
The common herbicide name for Brake is fluridone. Brake is in the same herbicide family as Zorial and, in fact, was heavily investigated as a potential herbicide in cotton a few years after Zorial was introduced in the late 1970s. Research was conducted on its’ viability as a herbicide in cotton at Jackson by Dr. McCutchen, Dr. Hayes, and others from 1976 to 1978. At that time, it was not found to be very effective on large-seeded broadleaf weeds like cocklebur and sicklepod and on top of that, it is very expensive to make so it was not pursued further in cotton. It was commercialized for aquatic weeds under the trade name Sonar. However, some researchers in the southeast remembered that it did have good small-seeded broadleaf residual control and pretty much as a region we have been evaluating it over the past two years for pigweed control in cotton. The research has really defined this herbicide’s strengths and drawbacks.
The strength of Brake herbicide can be summed up as good cotton safety and potentially impressive residual Palmer amaranth control. Our research as well as others has found that the cotton safety is very good. The injury to cotton is comparable to Cotoran or Caparol and way ahead of Reflex. In fact over the last two years, the most injury we have seen is some minor bleaching of the cotyledons with no check-up in growth. The other big plus is the longevity of Palmer amaranth residual control. Once it is activated, we have seen a good 4 to 8 weeks residual control of Palmer, depending upon rate.
So what are the potential drawbacks with this herbicide? The first concern is that it takes a good bit of precipitation to become active. My best estimate from the last two years is that it takes 0.75” to 1” of rainfall to activate Brake. During the dry 2012 spring when all we received was a few tenths of an inch of rain after application, our standards like Cotoran and Caparol were activated and the Brake never was. As you would imagine, the Brake plots were grown up messes. This is why we do research as we can stand grown up messy plots and you can’t. However this spring the standards like Cotoran lasted about 10 days before they broke while the Brake was providing residual Palmer control for a good 6 weeks after activation.
Another consideration is the time required to plant back to other crops. The rotation back to wheat and soybean is 10 months and the rotation back to corn is 12 months. In our work, particularly at high Brake rates, bleaching of wheat 5 months after application and corn 11 months after application could clearly be seen. The other concern is cost with a 0.10 lb/A rate running $25.00. Research from the 1970s showed that the rate needed to be at least 0.4 lbs to provide even partial control of cocklebur.
The research this year has also been designed to see if we could work around the drawbacks in order to access the herbicides strengths. We have been doing this by looking at much lower rates than they used back in the 1970s to help get the price down and minimize re-crop issues all the while trying to maintain good residual pigweed control. We have also looked at tankmixes with our traditional pre applied herbicides that do not need as much water to activate to get around the need for well over a 0.5” of rain for Brake to become activated. The results have been encouraging and we are looking at applying for a section 18 label for Tennessee where we might try this on a limited commercial scale in 2014. Stay tuned….. Attached is a post Stanley Culpepper had on this herbicide back in early March before we had this year’s results.
