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Get most from herbicides: Three keys to controlling rice weeds

The telephone calls have settled back into the normal range for this time of year. Hopefully this means everybody has a plan, whether it is the plan you really wanted or not. Let's get the rice crop in the ground and move forward. This too shall pass.

For a change, I'll focus on the task at hand when it comes to weed control. The keys to effective rice weed control at the lowest cost are: proper use of residual herbicides, herbicide/moisture relationships, and application timing.

The first line residual herbicide for most growers is Command. I recommend Command in both conventional and Clearfield weed control programs.

There are a lot of ways Command can be effectively used. If we are in a period of predictable showers during the planting season or if you are willing to flush, my recommendation is to use some rate of Command as a pre-emergence treatment. I like having it on the fresh seedbed, getting it activated, and controlling as much grass as possible before it ever emerges.

In the Clearfield system, Newpath and Beyond are both good grass herbicides. However, there is a huge advantage to getting most of the grass under control with Command so you mainly have to deal with red rice with the Newpath and Beyond. In addition, Command is much more effective on sprangletop than is Newpath.

If we are not in a predictable rainfall period or if you are not willing to flush, it may be wise to sit back and wait either for a good rain forecast or until you have to flush anyway. Then, apply the Command postemergence just ahead of the moisture event.

Tank mix it with a postemergence herbicide if weeds have emerged. In conventional rice, it can be tank mixed with Facet, Quinstar, Ricestar HT, Duet or Super Wham or Clincher. In Clearfield rice, it can be tank mixed with the first application of Newpath if necessary.

The programs I like best in conventional rice are those that use a combination of Command pre-emergence followed by additional Command, Facet or Quinstar or a combination applied in front of showers.

Getting residual herbicides out before weed emergence, getting them activated and then spotting in some additional residual to extend the control period is the first big key.

The second key is tying the herbicide applications to moisture. The residual herbicides require moisture shortly after application in order to work. With a herbicide like Command, you do not have anything until it is activated. With a herbicide like Newpath or Facet/Quinstar, you may get some postemergence activity, but the residual component is wasted without activation. Therefore, time the residuals right in front of moisture when at all possible.

Moisture also plays a huge role in postemergence herbicide activity. With postemergence treatments, make every effort to time them right behind moisture.

My wish for the year is one of timely showers. However, if you as much as suspect a dry period, get a postemergence treatment out to kill everything up (but the rice) before the weeds have any chance to become drought-stressed. I challenge you to keep the moisture keys in mind and you will be surprised how easy weed control will be.

The third key is application timing of postemergence herbicides. Waiting too late was the number one cause for failure when I started in 1974 and it still is. I guess that shows how effective I have (not) been.

You will never mess up applying a postemergence herbicide too early. Shoot for two-leaf grass because you will have some three- and even four-leaf grass by the time you get the treatment out. It doesn't matter what the treatment is, two-leaf grass and good soil moisture will make it hard to mess up. Add a residual component to it and get it activated and things will really be easy.

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