A weed control strategy in sorghum is important to help maximize yield potential but can be difficult and requires some planning.
Grass and broadleaf pressure can reduce yield and can make harvest challenging (Figure 1). Crop rotation, a comprehensive herbicide program, and planting sorghum into a weed-free field are key components for a weed management plan in grain sorghum.
A successful herbicide program depends on the weeds that are present in the field. Preemergence- and postemergence-applied herbicides can help to control broadleaf weeds. In fields with pigweed species, it is important to include a soil residual in the burndown program. This helps to minimize Palmer amaranth and waterhemp emergence in April and May. One of the weaknesses of any soil-applied program is the need for rain or irrigation for activation. Without activation, poor weed control can be expected. Postemergence applications should be targeted to address broadleaf weeds that are 2 to 4 inches tall rather than 6 to 8 inches.
Grass control in sorghum is very difficult. If a field has severe pressure from shattercane, Johnsongrass or sandbur, planting grain sorghum is not recommended. All grass species need to be controlled with a preemergence herbicide because there are currently no herbicides labeled for postemergence control in conventional grain sorghum.
Concep® III, a seed safener, enables the use of certain preemergence herbicides to be applied in grain sorghum. Remember to always follow the label when applying any herbicide and be diligent on following label rates and application restrictions to avoid early damage to the crop.
Thompson, C. 2016. Weed control strategies in grain sorghum. Update. K-State Research and Extension. Kansas State University. https://webapp.agron.ksu.edu/.
Web source verified 10/14/2020
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