Now that many growers are finishing up with field corn harvest, I have been getting lots of questions about the potential effects of late-season applications of glyphosate on the production of weed seed. Very glad to see that growers/agents are thinking about this issue. Preventing weed seed-rain back into a field is a great long-term strategy for improving future weed control programs.
Bottom line on this issue is that late-season applications of glyphosate can be very helpful in reducing weed seed production BUT ONLY IF APPLIED AT THE RIGHT TIME!
Check out Figures 1 & 2. You will note that glyphosate applications only reduced weed seed production when applied early. Generally, glyphosate applications made to plants with maturing seed were not as effective and would likely be a waste of time and money.
Many weeds in Georgia fields after corn harvest might already have maturing or mature seed. Thus, growers (with the help of their local county extension agent) should look very closely before blindly applying glyphosate with the sole hope of reducing weed-seed rain.