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Scout rice to determine need for midseason herbicides

Scout your rice fields carefully to determine if a midseason herbicide application is needed.

Two types of calls are difficult to handle. One is when herbicides are needed and the weeds are drought-stressed. The other is about fields that need a midseason herbicide application but the rice joints are beyond 0.5 inch.

The question is always, “How much injury should I expect from Grandstand or 2,4-D if rice joints are an inch or 2 inches or 3 inches?”

There is just really no good answer for that one. We know that the injury risk starts increasing at around 0.5 inch internode and continues through heading. Therefore when I get those calls I try to consider how bad the weed problem is, how far the joint has moved, what percentage of the rice plants are at this stage, etc.

I never feel really good when I hang up after one of those calls. By far the best way to avoid this question is to scout the fields carefully enough after flooding to be sure you do not let any hidden weeds surprise you at the back side of the application window.

Even when you find the problem and get the application scheduled, it can be several days before the conditions are right for your applicator to apply it. You do your applicator a big favor by giving him as much advanced notice as possible.

I have been to one field and was called about several others where 2,4-D was applied in the burn-down herbicide and the rice was planted back too soon. The result from this can be very severe injury.

Apparently, some think that because 2,4-D is registered for rice that tolerance should not be an issue.

Perhaps some also feel 2,4-D has no soil activity. In the early years, it actually had some pre-emergence uses on certain tolerant crops. Rice is not a tolerant crop and soil activity from this herbicide can be devastating.

The most conservative rule of thumb for plant-back on 2,4-D is 28 days. In most cases rice can be safely planted back in 14 days.

Sometimes it can be planted back even sooner.

It is quite common for a farmer who planted back in three days and has hammered rice to say, “I have been doing this for several years and have never had a problem.” Keep in mind that 2,4-D is broken down by microbial degradation. How active the microbes are depends upon a lot of factors that you have no control over.

If you need 2,4-D in the burn-down (I often recommend it), get it out a month before planting and then you don't have to guess whether it still may be there or not.

If you are using Grandstand as the midseason herbicide, make sure the rice crown is covered with water at the time of application and maintain the flood. This will reduce the injury risk with this herbicide.

In Clearfield rice, scout carefully for escapes. Wait as long as you can for as much of the red as possible to emerge from the canopy, but stay within the cutoff of 14 days after green ring. It would be nice if the cutoff was later, because the red usually does not emerge from the canopy until later.

I am still asking BASF for a federal label for Beyond that would allow the use of Beyond or Newpath in most situations. Where residual activity is needed, Newpath is the best choice.

In most postemergence applications, especially the preflood treatment, Beyond is actually a better choice, because it has better postemergence activity than Newpath. Right now it is not labeled for use until two Newpath applications have been made. This is a hindrance for those of us in the field.

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