We have already had a lot of residual herbicides applied in February and March that went two to four weeks without a rain for activation. The way you have to compensate for that inconsistency is to make multiple applications — stacking or overlapping.
Take a worst-case scenario where you know you have major pigweed issues and you are going to plant Roundup Ready soybeans. Perhaps you have been in LibertyLink a couple of years and want to rotate out or you just like the Roundup Ready system. In this scenario, you definitely need to stack or overlap residuals.
I just returned from the national meeting for weed scientists. It was a great meeting with a lot of excellent presentations. While a major emphasis at the meeting was on herbicide-resistant weeds, I was disappointed by the lack of emphasis on proactive resistance management.
In the next five years we will be using several non-chemical weed control methods to keep our herbicide programs viable. It will not be because you want to do these things, but rather you will have to in order to survive.
We must have a viable aerial application industry in Arkansas. Those guys have a highly visible industry. Not many of us would want the sort of visibility in our business they have on a daily basis. Their industry has risks involved that not many of us would be willing to take.
The first rope wick applicators for Roundup herbicide in Mid-South weed control simply used some nylon rope, 4-inch or so PVC pipe, some rubber grommets and a way to mount it on the tractor or other means to push it. You could buy them or make them yourself.
One colleague who has attempted to keep me straight through the years recently e-mailed a comment along the lines that “I do not see how weed species shifts are any different from herbicide resistance, although you seem to think so.”
When I began my career as a weed scientist in 1974, we had propanil (Stam), Ordram and the phenoxy herbicides in rice, which would seem like a very limited arsenal now. However, we got along quite well with them at the time.