Resistant pigweed in Roundup Ready soybeans
Oct 20, 2009 2:25 PM, By Ford L. Baldwin, Practical Weed Consultants, LLC.
I have written several articles on pigweed control in conventional soybeans. My next couple of articles will deal with Palmer pigweed control in Roundup Ready soybeans.
First, consider where we have come from. I want to give the conventional system every benefit of the doubt I possibly can. However, prior to the introduction of Roundup Ready soybeans, we could not consistently control Palmer pigweed in our research plots and growers could not do it in the field.
When Roundup Ready came along, you sprayed them and they actually died instead of getting mad and re-growing like they did with most conventional treatments.
If you missed the timing and they got too big, you just raised the rate and they still died.
I remember when a friend, who had fought pigweeds and failed for years got his first Roundup Ready seed. I had told him he would likely have to make two applications given the pressure he had. He was bragging that fall how clean his crop was. I asked him if he had to use the two applications. His reply was, “No, I had to use three and loved every minute of it because I was getting to watch them die!”
One grower recently commented during one of my presentations that when Roundup Ready came along he was still able to control his weeds conventionally but “Roundup Ready sure made things a helluva lot easier.”
I thought about that a minute and realized that it was Roundup Ready soybeans that made a rice weed scientist out of me. The reason was that after about the second year of production there was no more need for a soybean weed scientist, so I had to find something else to do to keep a job.
I could go on about how the technology has made weed control too easy, changed the way we farm, allowed more conservation tillage, allowed for much better efficiency, energy conservation, etc.
The problem is that glyphosate is not working any more on several weed species and the worst of those is Palmer pigweed. A lot of folks are having a hard time accepting that fact and a harder time accepting the fact that weed control has suddenly become more complicated.
Some are asking, “Why are you even writing about pigweed control in Roundup Ready soybeans if glyphosate won’t control them?”
A lot more farmers are asking me, “Why should I have to pay a technology fee if I have to use a conventional weed control program in my Roundup Ready soybeans?” I recently received a one line e-mail from a reader asking, “Why in the hell did he pay the technology fee” in response to a comment in a recent article about a grower’s residual treatment working so well that he did not need any glyphosate.
While I can sympathize and even have an opinion about that issue, I can not do anything about it. The technology has not suddenly become useless even though weed resistance to glyphosate is increasing.
In hindsight, we should have been in a program approach with the Roundup Ready technology for years; now the weeds are catching up. There is a place for more conventional soybeans in the right situations, and I believe the LibertyLink technology is going to be excellent and will increase as seed availability allows.
For 2010, however, seed supply alone will dictate that the majority of the acres will be planted to Roundup Ready.
As I stated in the last article, if you are going to plant Roundup Ready soybeans where you have a known pigweed resistance problem, you must treat them just like they were conventional soybeans. That means you will need at least one residual herbicide treatment and more than one will be better.
It also means you will need something like Flexstar in the first glyphosate application and that application must be timed for the Flexstar — not the glyphosate. Some say 2-inch pigweeds or less. I say 0.5-inch pigweeds or less.
I will summarize next week.
e-mail: ford@weedconsultants.com
