Rice herbicide development has been in the golden age for the past 15 to 20 years. Since the development and release of 2,4-D in 1944, we had only seen a handful of herbicides labeled for use in rice through 1999. Many of those herbicides are still around, such as, Stam, Prowl, Facet, Grandstand, Blazer, Basagran, Aim, Command and Bolero. However, some of them are no longer available for use in rice in the United States such as molinate.
Since the turn of the century, nearly 20 new active ingredients and/or prepackaged mixtures have been labeled for use in the U.S. for use in rice production. One would think with this success, development of new herbicides would slow to a snail’s pace; however, that has not happened.
In 2015, my research project evaluated 10 experimental herbicides. Many of these new compounds were in the experimental number stage. Many of these experimental herbicides will eventually make it to the grower in the next few years. I am going to discuss three that will be available in the next couple of years and could have a dramatic impact on weed management programs for Louisiana growers as well as for rice producers across the rice belt.
1. Provisia Rice is a new herbicide and herbicide-resistant technology. The rice and the herbicide will be called Provisia. This is similar to the glyphosate-resistant technology, where the crop and the herbicide have Roundup in the name.
The active ingredient in Provisia is quizalofop. This herbicide is considered an ACCase herbicide, which puts the herbicide in the Group 1 mode of action. The mode of action of ACCase herbicides is to affect fatty acid synthesis, which is a key component of cell membranes.
The ACCase herbicides primarily have activity on grasses. However, these herbicides have little to no activity on sedge or broadleaf weeds. Provisia will be a huge addition to the rice farmer’s herbicide arsenal by providing a new product to control red rice and other hard-to-control grasses that Newpath and Beyond no longer control.
I see this new herbicide-resistant rice along with the herbicide Provisia being an excellent option for growers with resistant red rice or other weedy rice plants. The big issue will be the lack of activity on sedge and broadleaf weeds.
My project has spent a great deal of time over the past three years working on weed management programs that can be used to take full advantage of the Provisia system, while at the same time developing programs that include products to control sedge and broadleaf weeds.
2. The next herbicide is benzobicyclon. This herbicide is being developed by Gowan, and it appears to be a herbicide that can be extremely useful in water- and drill-seeded rice that is flooded early in the growing season. Benzobicyclon is an HPPD inhibitor, placing it in the mode of action Group 27, and this will be a new mode of action in rice.
Anytime a new mode of action is labeled in a crop, it can aid in a herbicide-resistant management strategy. This herbicide has excellent activity on rice flatsedge, Amazon sprangletop and ducksalad. At high rates it also has some activity on grassy arrowhead, creeping burhead and cattail.
I have observed red rice activity in the greenhouse, which adds another twist to this particular product. This herbicide has an excellent fit in rice under flooded conditions; however, it should not be applied to rice prior to permanent flood establishment. Benzobicyclon can struggle with yellow nutsedge, hemp sesbania and Indian jointvetch, and it will probably be sold as a pre-package mixture with Permit.
3. The last herbicide I will discuss is Loyant, currently being developed by Dow AgroSciences. Loyant has very similar activity to 2,4-D; however, it is considered a new mode of action. This is one of those herbicides that may be “too good to be true.” Loyant has activity on grass and broadleaf and sedge weeds.
The major weakness of this herbicide is Texasweed. This herbicide must be applied postemergence and has little to no residual activity when applied on the soil. Loyant will also be more active when a methylated seed oil is used as the adjuvant system.
Preliminary research indicates rice is very tolerant when treated with Loyant at the 1-leaf to tillering stage. Loyant also appears to be safe in a water- and drill-seeded system. I don’t know the exact time of an expected label, but it could be in the next year or two.
In 2016, my project will evaluate approximately 11 experimental herbicides, many of these are different from those evaluated in 2015. I am an optimist; I see the glass as half-full and not half-empty, and this trend of experimental herbicides will continue in my opinion.