Herbicide Shortages/Supply Chain Issues. Much has been said and written about the potential shortages of glyphosate and glufosinate that are expected in 2022. And because of that fact, I'm not going to try to add too much more to this discussion. After talking about this with growers and retailers around the state and after my (admittedly abbreviated) winter meeting season, I'm also not sure who will have a shortage of these herbicides in 2022, and who won't. I've heard everything from, "we don't have any problem getting glyphosate/glufosinate in this area" to "we will be very limited in this area". So, if you anticipate that you may be unable to source enough glyphosate or glufosinate for your needs this season, my advice is simply this; determine the best way for you to use the herbicide(s) that you do have available for the good of your overall weed management program. This means targeting your worst weeds with the herbicides that give you the best opportunity for success first, and taking every opportunity to make the most out of the herbicide that you intend to spray. In other words, proper herbicide timing will be as important this year as ever (to eliminate the need for any potential re-sprays), as well as correct use of nozzles, adjuvants, GPA, etc.
In corn, we still have a variety of effective post-emergence weed management options and herbicide groups that do not involve glyphosate or glufosinate. These would include the group 4 (2,4-D, dicamba, etc.), group 27 (Callisto, Impact, Laudis, Shieldex, etc.), and group 2 (Resolve, Steadfast, etc.) herbicides. In other words, you can probably "get by" easiest in corn without glyphosate or glufosinate.
In soybean, we must rely on effective residual herbicides pre- and post-emergence as much as possible. Because of our problems with resistant waterhemp and Palmer amaranth, this is really something I hope that our farmers are already familiar with and practicing, regardless of any potential herbicide shortages. Also because of our problems with these resistant weed species, soybean is a crop where a potential shortage of glufosinate might hurt the most. If used correctly, glufosinate is still a herbicide that works on the pigweed species in most Missouri soybean fields. With that in mind, I would save all the glufosinate you have for post-emergence use in Enlist soybean (preferably with Enlist One), or for post-emergence use in Liberty Link, Liberty Link GT27, or XtendFlex soybean.
If you intend to utilize herbicides for termination of your cover crops, our data indicates that glyphosate or glyphosate mixtures are most often the most effective and most consistent option (see figure as well as previous articles on this topic). In my opinion, if I had to "save" glyphosate for use this season, I'd want to try to keep some of it for cover crop termination. But if you cannot find glyphosate and have to switch to another non-selective herbicide, our data indicates that tank mixes that include paraquat (Gramoxone) may be the next best alternative. Another option for the control of grass cover crops would be the application of a group 1 herbicide like clethodim (Select Max, Arrow, etc.) or others, but obviously these herbicides would not provide any control of legume or broadleaf weed species.