What is in this article?:
- Early-season weed scenarios and observations
- Compared to same period in 2013, early-season weed control this growing season "more problematic."
- Palmer amaranth becoming tolerant to Gramoxone?
It’s early June and planting in Tennessee is winding down.
What a difference a year makes! This time, last year, we were trying to finish corn planting, just getting into cotton planting and had hardly turned the tap on soybean planting. The results of that late planting was mixed as the soybeans yielded well, the corn also yielded well --though it took forever to get it to dry -- and the cotton, in many cases, ran out of growing season.
As in 2013, we will have another relatively large soybean crop due in part to excessive winter kill of wheat on later sowed fields and a wet late March and April that had some planting intentions move from corn to mainly soybean.
From a weed control perspective we saw more pre-emergence herbicide injury in soybean and cotton back 2013 than we did this spring. That is not to say we had no injury this year. We did, particularly for cotton and soybean just trying to emerge the week of May 22 in very cold and wet soil conditions.
We were going to have some struggling cotton and soybean stands with that weather even with no herbicide present. Young seedlings emerging with activated herbicides through cold and wet soil conditions magnified the problem. However, the soybean and cotton that emerged early or later than that week established stands in good order.
The jury is still out on the weed control effectiveness we are experiencing this year compared to 2013. Weed control has started out to be more problematic than what we experienced last spring. Most of May, it was often too windy to spray which resulted in late burndown on large Palmer amaranth in some cases. In other situations cotton and soybean planters were running without the sprayer backing them up with a pre-applied herbicide.
Those late burndown applications often resulted in inconsistent burndown of large Palmer amaranth with Gramoxone. This occurred even at high rates and in some cases mixed with a PSII inhibitor like metribuzin or Caparol.