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Serving: Central

One-shot rice weed control?

We are finally getting a break from the rain and a lot will be happening. I have had quite a few calls from folks wanting a “one-shot herbicide program.”

Some of the fields that have been too wet to do much to for so long are suddenly ready to clean up, fertilize and flood. I usually try to stay away from one-shot applications if possible.

Where there is a broad spectrum weed problem and those weeds range in size from just emerging to too big, it is often hard to come up a single recommendation that will do everything. My normal plan is to pick the most important weed species, hit them hard, and then wait a few days and see what is left. That approach usually gives a better overall result and also spreads the risk by not having all the eggs in one basket.

With that said, I have also recommended quite a bit of Ricestar HT plus Facet plus Permit where someone wants a broad spectrum approach.

This year there will be rice going to flood and rice being planted at the same time. With the adversity the early-planted rice has been through, there will be situations with big grass.

Prior to flooding, some of the “big grass” treatments I consider are Regiment (where the problem is primarily barnyardgrass) and Ricestar HT plus Facet (where the grasses include sprangletop and broadleaf signalgrass). Where sprangletop is not present, Regiment plus Facet can work well.

I have also been asked about mixing Ricestar HT and Regiment. I have found it to be a good treatment if you include Dynapak or equivalent recommended surfactant for the Regiment, and if the weed spectrum does not include tighthead sprangletop.

In Clearfield rice, big grass treatments can include Clearpath or a Newpath plus Facet mix, Newpath plus Ricestar HT, and in some cases Newpath plus Regiment. As before, if tighthead sprangletop is in the mix, I prefer the Ricestar HT and Newpath be applied separately.

Take some caution against the Newpath plus Regiment recommendation, because you are mixing two ALS-inhibiting herbicides. While I agree in principle that mixing two ALS-inhibitors is a bad resistance management approach, the first priority is to kill the grass if you are in a runaway situation.

Whichever treatment you choose, do not skimp on the rates. Hit the grass as hard as you can. It should be noted that Regiment should not be used on Bengal variety.

While I always recommend having nothing out there but rice and soil when the flood is applied, it does not always work out that way. After flooding, if the grass is only barnyardgrass, I recommend mostly Regiment. If it is only sprangletop, Ricestar HT or Clincher is the only choice.

Where the grass problem includes one or both of the above with broadleaf signalgrass, I often recommend Clincher plus Facet. I have a lot more confidence in the mixture than Clincher alone in a runaway situation.

In some situations where only barnyardgrass and/or broadleaf signalgrass are present, a half pound of Facet and crop oil can still be a good treatment if resistance is not an issue.

Some of these treatments can be very expensive, but leaving the grass can be much more expensive.

We will have a lot of late-planted rice. One would think that with warm temperatures and good moisture weed control would be easier in the later-planted rice. I hope last year’s experience by some was a fluke. However, some of the worst messes I saw last year were in late-planted rice and quite a bit of it was Clearfield. This difficulty caught me and a lot of consultants by surprise.

Hopefully, we will not experience the same this year. However, activate residuals if you need to. This can mean flushing. If you have escapes, you need moisture for good control in hot weather. This can also mean flushing.

Based on what I observed last year, any escaped grass — especially barnyardgrass — must be hit hard by the time it is in the two-leaf stage. Just based upon last years experience in Clearfield rice, I would not depend upon Newpath alone to control escaped barnyardgrass in the late rice.


TAGS: Rice
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