A common question I get is: “When do I need to mix another herbicide with Newpath?” I hate to answer a question with a question, but here is my reply. “What is your weed spectrum and which weed(s) do you specifically want to target?” The weeds present in a field will dictate which, if any, additional herbicide will be needed.
Many of the rice herbicides available to producers are compatible with Newpath at some time during the growing season, but there is never a one-size-fits-all weed control program. I do have my favorite programs I will recommend over others, but each program has a viable reason for selecting it. I will take this opportunity to discuss where these mixes may fit in a Clearfield rice production system.
Pre-emergence programs in Clearfield rice are fairly easy. Very little Newpath is applied pre-emergence since the release of the more tolerant rice Cultivars ‘CL 161,’ ‘CL 131’ and the RiceTec hybrids such as ‘CLXL 8. However, I believe fields with less red rice pressure may be a good choice for Newpath applied pre-emergence in order to spread your timings over a wider application window. If you consistently have a problem with sprangle-top and ducksalad, a pre-emergence application of Command is an excellent choice. Prowl, although not labeled pre-emergence, is a good option in drill-seeded Clearfield rice applied delayed pre-emergence or as a mixture herbicide in the first postemergence application of Newpath. Command and Prowl are very economical, control grasses and some broadleaf weeds and work nicely in a Clearfield production system. Command has a little more flexibility because it can be used in water-seeded rice production.
If your field contains more broadleaf weeds such as hemp sesbania and jointvetch, Facet or the new pre-package mixture of Facet plus Newpath - sold under the trade name Clearpath - is a nice option pre-emergence or as the first application in a total postemergence program. When using Clearpath in a total postemergence program you get the best of both worlds. The mixture will provide both pre-emergence and postemergence activity and effectively broaden the spectrum of weed control with one application. The other advantage to Clearpath is that it is more economical than purchasing the products separately and mixing them on your own. Clearpath should be applied at 0.5 pound of product per acre, which is the equivalent of 4 ounces of Newpath and 0.4 pound of Facet. If your target weed is barnyardgrass, a total postemergence program of Newpath may be a better option than pre-emergence programs. However, Clincher, Regiment or Ricestar HT may be needed for late season escapes.
In a total postemergence program there are several viable options for control of a broad spectrum of weeds in Clearfield rice production. The first postemergence application of Newpath should be applied to one- to two-leaf rice. The total postemergence program will provide control of red rice and grass weeds.
The first application of Newpath applied postemergence will also provide some control or suppression of broadleaf weeds through pre-emergence and postemergence activity. It is very important to add a crop oil concentrate at this timing. If a crop oil concentrate is not added at the first postemergence timing, control of emerged weeds will be drastically reduced.
The addition of another herbicide in combination with the first application of Newpath may be needed if the weeds are growing too rapidly to be controlled by the mixture at the second postemergence timing. In research conducted at the LSU AgCenter Rice Research Station, Crowley, La., the addition of propanil with the first Newpath timing provided excellent control of a broad spectrum of weeds. The crop oil concentrate is not needed if an EC formulation of propanil is used.
Another herbicide that can be mixed with Newpath at the early timing is Aim. Aim is economical and can be applied at a reduced rate to control small hemp sesbania and jointvetch. Another possibility is the addition of Clincher for control of grasses such as sprangletop and fall panicum. There is always a chance of antagonism; however, it is generally not a problem with the addition of Clincher when the target grasses are in the three-leaf stage or smaller. Similar results have been observed with Ricestar HT.
In other research, the addition of Permit and Londax, or the products alone, provided excellent control of hemp sesbania and jointvetch and added activity on yellow nutsedge and rice flatsedge. Activity of Permit or Londax applied to large hemp sesbania and jointvetch is reduced when these weeds are treated at the five-leaf stage or larger. Many options are available at the first application of Newpath; however, the second application may be the best time to add another herbicide.
The herbicides that were mentioned as potential mixes in the first Newpath application are also viable options with the second application. Research in Louisiana has shown that Regiment plus Newpath is an excellent combination. Regiment provides control of alligatorweed, dayflower, hemp sesbania, jointvetch, smartweed and large barnyardgrass escapes. This mixture also aids in the suppression of late emerging ducksalad. Newpath plus Regiment has always been one of the most consistent and best performing combinations in our research program.
Our research has shown that Aim, Permit, propanil and Regiment are some of the best products to mix with Newpath. Each product has a fit in a Clearfield production system but none of the products would be considered a one-size-fits-all weed control program.
The best time to control any weed is when it is small and actively growing. The Clearfield rice production system is no exception. Every field should be scouted and evaluated before a weed control program is selected. Always read the herbicide label before applying the product and contact your local extension specialist, consultant or company representative if you have any questions.
Eric Webster is a weed scientist with the LSU AgCenter Agronomy and Environmental Management Department. Contact him at [email protected].