With the frequent rains, we missed proper burndown timing. Now we must totally rely upon pre-emergent herbicide application and now are working on missing the proper timing for post applications. Consider adding a second component to that glyphosate application when you post- spray your corn or soybeans. The idea is to have a second method of attack on those weeds that may be resistant, have grown a little larger than planned or in areas where you have had problems with in the past.
The Ohio & Indiana Weed Control Guide is a great resource for getting management tips on how best to apply glyphosate — see page 13 in the guide. Also see the corn tables starting on page 55 and the soybean tables starting on page 119 to choose a potential partner for post applications. The Guide is sold out for this year but is available free on-line from Mark at https://u.osu.edu/osuweeds/files/2015/11/2016_Weed_Control_Guide-17h5o2i.pdf.
Don’t forget about drift. The spring burndown season was a little scary, and hopefully we will be into post spray season soon, so there is still potential for drift onto sensitive crops. Here from the Weed Control Guide are some tips on how to reduce the chances for drift.
Off-target movement of herbicides
Spray drift is the downwind movement of spray particles from the application site to non-target areas, some with sensitive plant species. The extent of spray drift increases as:
(1) the size of spray droplets decreases,
(2) the height above the ground from which the droplets are released increases, and
(3) wind speed increases.
Drift can be minimized by following these guidelines.
- Spray when wind speed is low.
- Use the maximum nozzle orifice size without distorting spray pattern.
- Reduce spray pressure to the lowest setting without distorting spray pattern.
- Using nozzles that minimize drift, such as Air Induction, Turbo Teejet, or Flat Fan DriftGuard nozzles.
- Use drift control agents when permitted by the label.
- Follow label precautions for drift reduction measures.