I have looked at a lot of fields lately where I have almost been afraid to recommend what I really thought it was going require to clean it up due to the cost. Weed control budgets in many fields have blown right out the pickup window.
I guess about the only bright side is fuel and nitrogen prices are lower than last year. I have made it clear in many phone calls and field visits that this is not a year to second-guess anything a farmer has been able or not been able to do because of the weather.
A lot of folks had good intentions for getting a pre-emergence herbicide applied, but they were caught by either rain or wind. There is daylight-and-dark difference in the amount of herbicide (and money) being required to clean up the fields that received a pre-emergence herbicide and those that did not.
The weed of the week has been dayflower. I am getting a lot of calls asking where all the dayflower is coming from or why it is so much worse this year.
There are two reasons it is worse this year. First, it is another of the weeds that likes wet conditions and it would be an understatement to say it has been wet. Another factor could be we are not controlling it in soybeans, so the soil seed bank is increasing.
Glyphosate is essentially a zero on dayflower in soybeans. It may get to the point you have to consider an alternative herbicide in soybeans. Basagran and Storm have excellent dayflower activity in soybeans but unfortunately they do not make very good tank-mix partners with glyphosate.
In rice I recommend several herbicides for dayflower control. Perhaps the most common herbicide included in the tank is Permit. With Permit, I do not recommend rates less than 1 ounce per acre when dayflower is present. Permit is actually better on this weed when it is tank-mixed with propanil, but it usually is good enough when mixed with other herbicides such as Newpath or Ricestar HT if the rate is up. Sometimes Permit can also provide some nice residual control in addition to the postemergence activity.
Another herbicide with excellent dayflower activity is Regiment. In conventional rice situations where barnyardgrass, smartweed or ducksalad is also present, this can make a nice treatment.
Perhaps the herbicide with the best dayflower activity is one that tends to be forgotten — Basagran. Since Storm contains Basagran, it is good as well. I actually like tank-mixing these with a quart of EC propanil in place of surfactant or crop oil on this weed.
Comparing numbers in the MP-44 (Recommended Chemicals for Weed and Brush Control in Arkansas), propanil plus Permit, Regiment and Basagran are all rated a “9” on dayflower. At midseason, 2,4-D and propanil plus Grandstand also have “9” ratings.
Some other treatments that can have good activity on small dayflower include Londax, Duet, propanil plus Bolero or RiceBeaux, Permit plus Grandstand and Grasp. These have “8” ratings in the MP-44.
The choice of herbicide for dayflower often comes down to size and the other weeds you are trying to control. On small (one- to two-leaf) dayflower, any of the herbicides listed above will likely provide adequate early suppression or control. If it gets larger than the two-leaf stage, the herbicides with “9” ratings are going to be better choices.
With all of the early treatments, re-infestation may occur and require a midseason treatment. If you are treating at midseason anyway for morningglories or other weeds, you will get the dayflower. Actually in lighter infestations where you will be making a midseason treatment anyway, you may just choose to control it then.
Keep in mind, however, dayflower is a “dockage weed” much like morningglories, so whether you spray it early, late or both, it needs to be controlled regardless of the infestation level.