Photo credit – University of Nebraska (https://cropwatch.unl.edu/2019/post-harvest-weed-control-winter-wheat)
Pre-harvest herbicide applications may be needed in wheat fields that have a lot of weed growth due to the recent wet weather patterns. These herbicide applications address several issues such as harvest difficulties, dockage problems, weed seed production, and soil water depletion. Although it may not be possible to recover lost yield potential due to weed interference, a pre-harvest treatment can go a long way toward reducing weed problems in future years by preventing the production and spread of weed seed.
Herbicides labeled for use as harvest aids in wheat are listed in Table 1. There are differences in how quickly they act to control target weeds, the interval requirement between application and grain harvest, and the level or length of control achieved. All of these herbicide treatments will require thorough spray coverage to be most effective and can be used once wheat reaches the hard dough stage, which is usually defined as 30% grain moisture or lower. If saving wheat grain for seed, be sure to check the germination of the treated seed before using next season.
Consult the Ohio, Indiana, Illinois, and Missouri Weed Control Guide (WS-16) or the herbicide label for more details on herbicide use and weeds controlled.
Table 1. Selected herbicides labeled for use as harvest aid treatments in winter wheat.
| Product and Rate | Weeds Controlled | Application Timing | Pre Harvest Interval | Comments |
| Clarity (8 oz/A) | Broadleaf | Hard dough | 7 days | Do not use treated wheat for seed unless a germination test results in 95% or higher germination. |
| 2,4-D (1 pt of 4 lb gal or 2/3 pt of 6 lb gal) | Broadleaf | Hard dough | 14 days | Weak on kochia and wild buckwheat. |
| Glyphosate (1 qt of 3 lb ae/gal or 22 oz of Pmax) | Grass and broadleaf | Hard dough | 7 days | Consult label for recommended adjuvants. Use of AMS is recommended. Not recommend for wheat being saved for seed. |
| Sharpen (1-2 oz A) | Pigweeds (waterhemp) if not PPO-resistant and wild buckwheat | Hard dough | 3 days | Use with glyphosate. Apply with MSO and AMS. |
