The current supply chain and labor market issues have contributed to shortages of several key pesticide products on the market. Glyphosate is the main herbicide used for pre-plant burndown weed control in corn, cotton, soybean, and peanuts in South Carolina. With that shortage, herbicide costs have skyrocketed in 2022. For growers who cannot obtain enough glyphosate or glufosinate, paraquat is an alternative for pre-plant burndown. Since paraquat is a fast-acting herbicide with no soil residual, applications can go out relatively close to planting.
The key to success with paraquat is to apply to actively growing weeds with abundant sunshine following application. For larger broadleaf weeds, such as primrose and mustard, add 2,4-D at 1.5 to 2.0 pt/A for enhanced control.
If using 2,4-D with paraquat, observe the plant back intervals following 2,4-D application (i.e., 21 to 30 days for 1.5 to 2.0 pt/A).
The following table, provided in the link below, provides potential alternative herbicide combinations for burndown in corn, cotton, peanut, and soybean. The key for 2022 is to use soil residual herbicides throughout the season because of the reduced availability of glyphosate and glufosinate. For the overview programs in the attached PDF, consult the 2022 Pest Management Handbook for rates and waiting intervals between application and planting.