When we first discovered the resistant strains on our farm, it opened our eyes. We began to see that weeds could be resistant to glyphosate, not just harder to control. We had no choice but to be proactive rather than trying to make reactive decisions about weed control. We chose a variety of techniques to stay on top of resistance – scouting, crop rotation, tillage variations and multiple modes of action.
Are there other threats on your farm besides resistant marestail?
Right now we’re watching Palmer pigweed. It is an emerging threat to farmers in the area and throughout the South. Eight to 10 years ago, glypho-sate could take out a Palmer amaranth taller than your head. Today, it is much less effective. To make matters worse, I place Palmer pigweed at the top of the list as far as the amount of damage it can do. We have to prevent this weed from ever growing in the field.
What kind of strategy can you use against either of these troublesome weeds?
The bottom line is that it is difficult to raise a crop without glyphosate. We need to listen to weed scientists, what they are telling us and showing us. There is value in putting other chemistries in the field to maintain yields and preserve technology. We plant 100 percent glyphosate-tolerant cotton and 100 percent glyphosate-tolerant soybeans. That’s why it is important for us to employ residual herbicides and methods like burndown.
Last season we used Reflex herbicide for the first time. We were happy with the level of control. Plus, it also seems to outperform some pre-plant herbicides that we are using because it is not disturbed by the strip-till process. Envoke herbicide has also been used in some of our fields as a more economical alternative.
What about planting corn to deal with the resistance problem?
Corn is not a popular crop here. We don’t have the soil for it. But with higher commodity prices, we can still be profitable with marginal yields. We plan to work corn into our rotation. This year, we will plant glyphosate-tolerant hybrids, but our plan is the same. We will rely on residuals. Glyphosate will be a backup plan in case grasses get out of hand.
What lessons can be learned after several years of battling weed resistance?
Some producers believe that a new chemistry or silver bullet will come along to control resistant weeds. That’s not how I feel. I want to preserve glyphosates. It will be very difficult to replace glyphosate, especially something that can be that cost-effective and broadly used.
When glyphosate-tolerant crops first came out, everybody let weeds grow out, and then they would spray, and in a week’s time they would have a perfect field. Now we know weeds that are too large have an impact on crop yields and become harder to control.
Do you feel that your early efforts paid off in dealing with the problem?
I feel like it has paid off for us even though I still see isolated cases. However, I haven’t seen anything that is widespread right now. From that standpoint, I feel pretty good.
Do other North Carolina producers appreciate the seriousness of the resistance problem?
I’m not sure that our farmers understand the nature of this problem now. A lot of them might take the approach that they’ll wait around and hope that a cure for the resistance problem is discovered. I’m afraid that we won’t see anything like that.
What have you learned in the past eight years on how to deal with pigweed and marestail?
If there is anything that we’ve learned, it is that we better stay alert and not get caught sleeping. When these resistant weeds go unchecked for a couple of years, they can get out of control in a hurry.
Were there other things that gave you an early warning about the problem?
Don’t ever underestimate the value of your consultant. My consultant is Will Connell of Stokes, N.C., and he was very helpful in staying on top of the problem. I also recall that some of my professors at North Carolina State University were talking about this problem about five or six years ago. They were preaching this theme at the front of the classroom. As for how Will helps me, it’s a team effort. He does the scouting, and we work together to put in a program that works. I’d like to think that our work is paying off, and that we’re on the right track.
Gibbs & Soell, which
represents Syngenta, contributed information for this article.