Last year the phone lit up with calls about dayflower control in both rice and soybeans.
Up to that point I had only a few calls and little data on this weed in either crop. Much work had already been done in the past.
My initial reaction in soybeans was that it might be resistant to glyphosate, as we had never had that many problems with the weed in the past. So we did what weed guys do, we found a couple of the problem fields out in the state and set up some trials.
My goal in these fields was to evaluate tank-mix partners with glyphosate for dayflower. We set up the trials with Roundup WeatherMax as the first treatment, then added about every other soybean herbicide we could think of as a tank-mix partner. We even applied some Ignite, even though these were not LibertyLink soybeans.
The problem is, at both sites, 22 ounces per acre of Roundup controlled 5- to 6-inch dayflower about 99 percent when applied alone. Therefore, all the other treatments were essentially meaningless and we did not learn much for our efforts.
What is worse is that I continue to get calls about failures from the field and we cannot explain why.
The answer in soybeans is not what folks want to hear. Basagran is probably the best tank-mix partner for dayflower; Storm would be second. There is nothing wrong with these products, they just cost more than some other options and can be hard to find, especially later in the year.
I do not get too many dayflower calls in soybeans where residual products are used. I think most of the Valor products, Prefix, Authority MTZ and Boundry, all control or at least suppress dayflower if activated. There are probably other products that have activity on dayflower.
We are working with a couple of county agents to look at some of these products alone this year to hopefully get some useful data. Dayflower is a tricky weed to work with and it can be hard to get it to cooperate in weed control plots — that is, get it to be where it is supposed to.
In rice dayflower seems to be more of a problem in wet years. This probably goes for dayflower in general.
The best residual product for dayflower is Bolero. In fields where this weed is a problem year after year, Bolero or Bolero + Prowl H2O has been a good treatment. The new product RiceBeau (propanil + Bolero) would be good if you can get it out ahead of the dayflower.
In rice (post), the best treatments we have looked at are: Basagran or Basagran + propanil, propanil + Permit, or Regiment. 2,4-D is also good mid-season if you are not in a 2,4-D-restricted zone. I think if you go the Permit route you should use at least 1 ounce per acre; full rates of the other products as well.
Other treatments that I recommend from time to time include: Duet, Grasp, Permit alone, or Grandstand Permit. These treatments are pretty good on dayflower and may be used because they control other key weeds in the field.