Still getting a few calls about post-harvest weed control. Here are a few questions and answers for you regarding post-harvest weed management:
1) What's the best option to control volunteer corn (up to 12" tall)?
Select Max 0.97EC @ 6 oz/A or Select 2EC (clethodim) @ 4 oz/A (or generic equivalents) + COC @ 1% v/v. I have never had much success controlling volunteer corn with either Liberty (glufosinate) or Gramoxone (paraquat). Don't forget that many of the corn hybrids grown in Georgia today are RR+LL. The plant-back restriction for wheat after clethodim is 30 days. A hard freeze also works well with no plant-back restrictions.
2) Can you control Benghal dayflower/tropical spiderwort with 1 herbicide application?
NO! 2 applications (14 days apart) of either Gramoxone, Aim (carfentrazone), or 2,4-D will be required. Dicamba is NOT recommended for the control of this weed.
3) What is the plant back restriction for wheat after an application of dicamba?
All depends upon the application rate (0.25 lb ae/A = 15 days; 0.50 lb ae/A = 30 days).
4) What is your favorite post-harvest treatment?
I have had good success controlling many post-harvest weeds in my field corn plots, including volunteer corn, with the combination of Gramoxone + Tricor (metribuzin). But, small grains are not a viable rotational crop option after this one. Gramoxone + Tricor is much more effective on volunteer corn than Gramoxone alone. Check out the link and picture below:
https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/TriCor_4F_2EE1.pdf
5) Will late-season applications of glyphosate have an influence on weed seed viability/germination next year?
Generally, glyphosate will only affect weed seed viability/germination if applied around flowering or initial seed set. Later applications will have little effect on weed seed viability/germination for next season.
6) Any additional info in 2022 UGA Pest Control Handbook about this topic?
Yes, more specific information can be found on pages 74 (tropical spiderwort) and 86 (Palmer amaranth).
