By Greg LaBarge, Ohio State University Extension Agronomy Field Specialist
The first question in that statement is: are herbicides available for fall burndowns? We hear there are shortages. Fall herbicides do work and can be an excellent start to your marestail management program. This year we let our marestail get too big in many areas and we still had a few out there at harvest.
We are just compiling the Extension fall soybean weed surveys; it is not quite so bad as last year but we still see waterhemp, giant ragweed, and marestail. The number of clean fields has gone up it looks like, likely due to earlier planting and then better timing on that first post application.
I spoke with Tony Dobbels recently (on Mark Loux’s team) and discussed preliminary results of the fall survey. His response was that we have good technology for dealing with all of these weeds – RRExtend, LibertyLink and now Enlist3. But timing is critical again this year as always. So speak now with your seed supplier, and your herbicide supplier. Plan to use a different program than you used last year. Add pre-emergent herbicides at planting or with that burndown 7 to 14 days before planting. And in waterhemp areas (there are lots of those) add an additional pre-emergent herbicide at post application timing to extend your residual program. Good products are Zidua, Warrant, even Dual.