Pre-emerge success keeps weed costs down

In several recent articles I commented about $100-per-acre rice weed control programs in situations where excellent initial control is not achieved. I arrived at the figure because it is a nice round number and one that would pretty quickly add up when you have to use multiple applications of multiple herbicides.

In recent conversations with Bob Scott, weed scientist, and Chuck Wilson, rice agronomist, both with the University of Arkansas, the rice verification program came up. In the rice fields enrolled in the verification program, very detailed records are kept.

They informed me there were essentially two types of weed control programs in the 2008 verification fields — those with herbicide costs in the $30 to 50 per acre range and those around $100 per acre.

The $100-per-acre figure I have thrown around in not a figment of my imagination. The interesting thing, however, was the difference in the $30- to $50-per-acre programs and the $100-per-acre programs.

The difference was essentially whether or not a pre-emergence herbicide was activated before weed emergence. If the pre-emergence treatment was activated timely with a rainfall or flushing, weed control was relatively simple and inexpensive.

The lowest herbicide cost in the program was $30 per acre. In that field, the grower used Prowl plus Facet delayed pre-emergence, flushed it in, and did not have to do anything else for weed control. I have also seen this happen with Command pre-emergence.

These programs will be the exception rather than the rule. However, a properly activated pre-emergence treatment will usually set the field up so that one postemergence application will put things in good shape.

When the pre-emergence herbicide failed, the same thing that I have written about all winter happened in the verification fields. That is, they made repeated applications of multiple herbicides trying to get things back under control and the cost went through the roof.

Barnyardgrass is simply getting more difficult to control and growers are not going to continue to spend $100 per acre for herbicides. Worse than that, when this situation occurs, the weeds often are not completely controlled after all that money is spent.

There are two take-home messages here.

The first is we are ultimately going to need some new technology or rice is going to rapidly lose ground to crops with better weed control technology. I personally believe new technology will have to be in the form of genetically modified crops. Things are beginning to move forward in some countries and more dialogs are taking place in others. That is a topic for future articles.

The second message is one many farmers do not want to hear and that is the dreaded word “flush.” I have often made the statement “as the Command goes, so goes the weed control program.”

Prowl plus Facet or Quinstar is also an excellent treatment and I would include it in the previous statement. When you commit to these treatments as well as Newpath pre-emergence in Clearfield rice, and if it doesn’t rain before grass emergence, they must be flushed or they fail.

I have heard the figure of $12 per acre thrown around for the cost of flushing. You can put in you own figure. However, it has been obvious the past couple of years (and the verification fields essentially prove) that the success of our current programs depend upon the soil residual herbicides.

The difference in cost is the $12 or whatever you factor in for flushing (I already know you do not want to) versus $50 to $100 per acre in additional weed control costs. Bigger than that, the difference may well be good weed control versus a failure.

Until something better comes along, we simply must make the soil residual herbicides work.

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TAGS: Soybeans
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