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No answer for pigweed

I believe this is the latest soybean crop Arkansas has seen in at least the last 10 years. I am getting calls on pre-emerge treatments, as well as on flowering beans that are about to canopy.

We got off to a very rough start this year with missed burn-down opportunities and have had to battle glyphosate-resistant horseweed in-season. About the only treatment that has worked for me in my trials has been 0.3 ounce per acre of FirstRate herbicide in each post shot of Roundup. This will not completely control big horseweed, but will make a bean crop. Thankfully the horseweed calls have started to dwindle down now. It is a good thing because supplies of FirstRate are about gone.

We have seen an incredible increase in the use of residual herbicides for soybeans in 2009. I do not know the numbers, but based on my phone calls, sales of Dual, Prefix, Authority MTZ and the various forms and mixtures of Valor have to be up this year.

For the most part, earlier-planted beans got rain to activate these pre treatments. We have a glyphosate-resistant pigweed demonstration plot near Keo, Ark. When my crew finished spraying the pre treatments, which included Dual, Envive, Prefix and Authority MTZ, they were basically chased out of the field by 0.6 inch of rain on moist soil. The pre treatments were activated and look real good. You can definitely see the benefits of having residuals where pigweed is a problem.

Unfortunately, not everyone was able to get residual treatments out or get them activated. For about the past 10 days I have averaged two to three calls per day on pigweed failures with glyphosate across the state. Some of the fields were known to have a pigweed problem and others have caught producers and consultants totally off guard. But one thing is for sure, the problem is here, it is all over the state and it must be addressed.

The bad news is that by the time I get a call it is usually too late. There has already been a failure of glyphosate to control the pigweeds and now they are over a foot tall. No herbicides currently available will kill a foot-tall pigweed in soybean. FlexStar at a full rate, at least 1.25 pints per acre is about the best you can do, and it will not kill them.

Even if the field is in LibertyLink soybeans, Ignite will not completely control very large pigweeds. In LibertyLink soybeans, the first Ignite application should go out on 2- to 3-inch weeds and grass.

I have written a lot about LibertyLink soybeans this year and last fall. I am told that even with only around 150,000 acres available for the initial launch this year, they did not sell out. I am not sure why this is, especially considering the calls I am getting on pigweed failures. One reason in Arkansas is that the varieties were not in the University testing program until this year.

I do not blame a grower for not wanting to take a risk on unproven technology.

Another reason is that Ignite will kill non- LibertyLink soybean. This means that you must clean out booms, watch drift, and watch what field you are in carefully. All these are valid concerns.

I have seen numerous fields of Ignite drift this year and am aware of one field of Roundup Ready soybeans that was accidentally sprayed with Ignite. However, I think the need for pigweed control is going to force many to consider this alternative to Roundup Ready.

One final note, as new weed problems emerge, the need for old chemistry to be in stock and for new chemistry to be readily available when farmers need it are crucial for everyone’s success. I worked for two different ag chemical companies in my previous life and understand the cost of inventory; however, there is also a cost associated with not having product at the point of purchase to meet demand.

I already mentioned the shortage of FirstRate. This was announced back in April and now I am hearing that many growers are having trouble finding enough Ignite to spray the LibertyLink soybeans. This is probably due to high demand for Ignite as a burn-down product this year.

I just hope the weeds do not get too big while applicators search for material.

Just a note to manufactures for next year, we will have a bunch of horseweed and pigweed so stock up!

TAGS: Soybean
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