The landscape relative to rice is beginning to look more normal in many areas of Arkansas, even though much of the crop is late. It could prove to be an interesting weed control year.
Weeds respond differently to different environments. Do not be surprised to see weeds you do not normally see in any given field. It has been a cool wet spring and that can trigger earlier germination of weeds such as eclipta or sprangletop, for example. In addition, a lot of fields have been flooded by bayous and rivers or have been under water backed up from ditches or other fields.
That can change the weed spectrum. I have seen more fall panicum than normal for this time of year. Scout carefully and do not be surprised if you find something new.
A lot of the earlier-planted rice has had one or more pre-emergence treatments activated and may be in excellent shape from a grass control standpoint.
However, I am getting a lot of calls on broadleaf and sedge weeds. Farmers, consultants and weed scientists (including this one) alike often struggle with broadleaf weed control. If you make just a few right decisions, grass control can be relatively simple. With broadleaf weeds, most of the available herbicides simply do not have the spectrum of control needed.
When several species of broadleaf weeds are present, any given herbicide may be outstanding on one or two of the weeds and very weak on the others. In addition, the ability to control certain broadleaf weeds changes very quickly with time. For example, groundcherry, pigweed and smartweed are very easy to control when they are very small and almost impossible when they get larger — the breakpoint can be as early as 3 to 4 inches tall.
Therefore, in some fields where grass control is good but are being covered by broadleaf and sedge weeds, use my grass control philosophy of “hit them quick and hit them hard.”
There is no way to give you an ideal treatment here, because there are so many situations. I recommend a lot of mixtures of products. Aim and Permit or Permit and Grandstand are two.
Regiment can be an excellent broadleaf choice in some situations and Strada can fit, especially in Clearfield rice. Some things are easy to lose sight of, however. Facet and Quinstar can provide both postemergence and residual suppression of weeds such as groundcherry, coffeebean or indigo. Therefore, when something like Aim is used for groundcherry, for example, I often recommend some quinclorac in that mix.
Another thing I often recommend in a broadleaf mix that may not normally include propanil is substituting a quart of EC propanil such as Stam for the crop oil that may be called for. The solvent in the EC will act as crop oil and can often provide some nice “heat 'em up” as well. Some have forgotten just how good a gallon of propanil alone can be on broadleaf weeds. It still has a place — especially in mixtures.
Another old herbicide that has been pushed aside is Storm. While I may not recommend a lot of propanil plus Storm, I still fall back to it in some of the broadleaf weed situations where you need something hot. When the situation arises that you need something broad spectrum and hot, 2 to 4 quarts of propanil and 1 to 1.5 pints of Storm can fit the bill if you have the nerve.
Stick up a “no smoking” sign up at the field and don't go back and look at it for a week!
The weed response ratings in the University of Arkansas MP44 are a good way to help pick the herbicides that are best on any given weed. From there you often have to pick mixtures of two or three broadleaf herbicides that fit what you have.
You also have to factor in things like susceptibility of adjacent crops and any potential for antagonism between the chosen herbicides.
Broadleaf weed control used to be simple, but not anymore. The weed spectrum has changed, and we have to change with it.
Several people have asked me if I am still consulting for Riceland Foods members. I sure am. My Riceland cell phone is (870) 674-7297 and my personal number is (501) 681-3413.