Postemergence weed control is an important aspect of wheat production, as weeds can significantly reduce yields and quality of the crop. Effective postemergence weed control involves proper timing and selection of herbicides, as well as good crop management practices.
The timing of postemergence herbicide applications is critical, as wheat is generally most sensitive to herbicide damage during the jointing to boot stage. Pyroxsulam, 2,4-D, dicamba, flumioxazin, MCPA, and tribenuron-methyl are some of the herbicides that can be used during this stage. Herbicides that are applied earlier in the season, like Axial, will target grassy weeds while having no effect on weeds like wild oat.
Herbicide selection should be based on the type and density of weeds in the field. For example, ALS-inhibiting herbicides like Atlantis, are effective against grassy weeds like wild oats and cheatgrass. However, these herbicides may not be effective against broadleaf weeds like sow thistle and kochia. Alternatively, herbicides like fluroxypyr + MCPA can effectively control both grassy and broadleaf weeds but may not be effective for weeds like wild oat or volunteer barley.
In addition to herbicides, there are cultural practices that can help reduce weed pressure in wheat fields. Crop rotation, tillage, and timely planting are a few examples. Crop rotation is highly recommended, as rotating broadleaf crops with wheat can help reduce the weed population.
Another cultural practice that can reduce postemergence weed pressure is maintaining good uniformity of wheat stands. By ensuring that wheat plants are spaced evenly and are of similar height, the crop canopy will close faster, reducing light availability to weeds and limiting the growth and development of weeds.
Overall, postemergence weed control in wheat requires careful consideration of herbicide selection and timing, as well as the use of cultural practices that can contribute to a healthy and productive wheat crop. By following these guidelines, growers can maximize yields and quality while minimizing the negative impact of weeds.