Residuals in Beans, Not Just For No-Tillers

In our neck of the woods in SE Wisconsin, we don't have Roundup resistant weeds yet.  We have a few populations in our area that I would say have tolerance to traditional levels of in crop applications of glyphosate.  Reistance and tolerance are two totally different things, resistance means no rate of glyphosate will bring down the weed, tolerance can mean that no labeled in crop application will bring down the weed.  When a 44oz rate of branded Roundup won't bring down 12" giant ragweed it's a major cause for concern.  A lot of people see a yellow giant ragweed plant and think it's dead, but we are noticing a lot of these plants are only having the main growing point killed and are refocusing their growth to their axillary buds, or secondary growing points resulting in bushes not tall plants.  For us, residuals in corn has been a no brainer and in soybeans it's an afterthought.  For the last 17 years we have been using Roundup post in soybeans with good to excellent control, but those years are coming to a close.  With every year we use only one mode of action and spray weeds once as late as possible to get by with one pass we are selecting for weeds that will develop tolerance to Roundup.  Tank mixing with glyphosate is an option, but the reason we loved glyphosate is that those older herbicides weren't the greatest control in the first place.  Many were ALS herbicides that quickly developed resistance.  In soybeans, your best option for good control of weeds is to see little to no weeds coming up in the first place, hence residual herbicides.  I realize when you work the ground ahead of the drill it takes care of the initial flush of weeds, but they will grow back just as fast as your soybeans. 

I wouldn't say that Roundup is a tool that we have lost, we haven't yet in our area.  It's a tool that we need to manage, take a step back and re-evaluate how we are using it.  I have seen fields back home in Indiana with tolerant and resistant marestail, and now they are getting palmer amaranth from using only glyphosate at cut rates to kill weeds.  That's a mess we don't need or want here.