Why a Particular Herbicide Is or Is Not Recommended in Your Area

— Written By Carol Hicks

Eric P. Prostko with University of Georgia explains behind-the-scene details about herbicide weed recommendations. Read the article below or visit Southeast Farm Press.

This is the time of year when you likely have a little more time to read up on new products. You might wonder why a particular herbicide is or is not recommended in your area.

Manufacturers spend a lot of money on colorful advertisements proclaiming the virtues of their products. These ads might lead you to believe that you are missing out on something. That’s where university weed scientists like me come into play.

It has been my experience over the last 28 years that growers are always on the lookout for the next Silver Bullet or Holy Grail for weed control. By that, I mean an herbicide or system that is cheap, environmentally friendly, controls lots of weeds, has a low potential for the evolution of resistance and causes minimal crop damage; that’s more like finding a needle in the haystack.

Before any herbicide can be “officially” recommended by a land-grant university, it must undergo extensive field testing. Crop safety, weed control, and carryover are typically our biggest concerns. I will not put any new product in our UGA recommendations unless data has been collected for at least 2-3 years, maybe more.

For example, I currently have data from more than 40 studies on the potential use of Zidua (pyroxasulfone) in peanut with the goal of getting a registration sometime in the very near future. By the time the label is obtained, I should know very well how to advise peanut growers on its best use.

Many of you out there may have farmer-friends in other parts of the country that use herbicides that are not routinely recommended in the Southeast. You have got to remember that areas such as the Mid-West are blessed with higher organic matter soils that contain greater amounts of clay/silt and a much lower percentage of sand. Consequently, growers in that region can use herbicides that might cause unacceptable crop damage in our sandy and lower OM soils.

Another point to consider when evaluating any new herbicide is will it be better than what you are already using? Better meaning improved weed control/crop safety and more desirable crop rotation restrictions. I have been screening herbicides since the late 1980’s and have seen some good ones and some bad ones. The bad ones never make it to the farm gate. Thus, most herbicides on the market today will provide sufficient weed control when used according to the labeled instructions without major differences. However, I will be the first to admit that some herbicides are better than others on particular weed species. For example, Southeastern peanut growers should know by now that bristly starbur/goathead/Texas sandspur is extremely sensitive to Strongarm (diclosulam).

Lastly, many herbicides are initially developed for use in the major field corn, soybean, and wheat growing regions of the U.S. These crops were planted on more than 226 million acres in 2015! Peanuts and cotton are not typically grown in those states so herbicide label rotation restrictions for these specific crops are often very prohibitive due to a lack of knowledge and adequate field testing.

A significant amount of resources (i.e. time, money, and sweat) go into the development of “official” university weed control recommendations. Don’t take the chance on using products that have not been properly tested in your state. If a Holy Grail or Silver Bullet is available for your area, I am sure that you will be made aware of it. But remember, Holy Grails and Silver Bullets have been few and far between in my career.