Just a few things to follow up on after our recent weed science training on December 2:
1) If you are looking for something to help you better understand herbicide modes of action (MOA), check out the Herbicide Resistance Action Committee's (HRAC) 2020 MOA Classification Chart. A good one for your pickup truck library.
https://hracglobal.com/files/HRAC_Revised_MOA_Classification_Herbicides_Poster.pdf
2) We had some discussion about the potential residual effects of glyphosate on crops and some of the research that we are conducting. It's a very complicated issue influenced by many factors (soil type, OM, pH, other soil cations, application rate, timing, species sensitivity). However, I am not really worried about the residual effects of glyphosate on most major row crops grown in Georgia.
I was asked specifically about the effects of soil pH on the adsorption of glyphosate. In general, as soil pH increases, soil adsorption of glyphosate decreases (Figure 1). This also happens with herbicides in other families such as the triazines (atrazine) and sulfonylureas (chlorimuron). But, just because glyphosate adsorption is decreased as soil pH increases, it does not automatically mean it will cause excessive crop injury.
