Sorghum Herbicide Rotation Restrictions to Soybeans in Oklahoma
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Effective weed management is crucial for optimizing crop yield and ensuring sustainable agricultural practices. In modern farming, herbicides play a pivotal role in controlling weed populations, enhancing crop productivity and minimizing manual labor. However, the indiscriminate use of herbicides can lead to the development of herbicide-resistant weeds and pose environmental risks, e.g., off-site drift.
One significant aspect of herbicide management is understanding rotational restrictions, especially when transitioning between different crops within a rotation cycle. Sorghum and soybeans are staple crops in many agricultural regions, each with its unique herbicide requirements and constraints. When rotating from sorghum to soybeans, producers must carefully consider herbicide residual effects to prevent potential crop injury and ensure effective weed control.
This publication aims to explore and inform producers of the rotational restrictions associated with herbicide usage when transitioning from sorghum to soybean systems. By examining key herbicides commonly used in sorghum production and their residual impacts on subsequent soybean crops, producers can make informed decisions to mitigate risks, optimize herbicide efficacy and promote sustainable crop production practices.
Understanding the dynamics of herbicide residual activity, soil characteristics, crop sensitivities and regulatory guidelines is essential for successful crop rotation management. Through proper planning and adherence to rotational restrictions, producers can maintain weed control effectively while safeguarding crop health and maximizing yields in sorghum-to-soybean rotation systems.
Soybeans with sulfonylurea tolerance traits (“STS”) are designed to assist soybean plants in managing previously applied sulfonylurea herbicides, typically by reducing the duration of rotational restrictions after application. The BOLT soybean trait offers enhanced tolerance to sulfonylurea herbicides. However, despite the provided tolerance to sulfonylurea herbicides through these traits, adherence to rotational restrictions is essential to minimize the risk of potential crop damage.
The tables provided below offer a concise overview of frequently utilized herbicides in sorghum production in Oklahoma, along with their corresponding rotation restrictions for soybeans. This compilation serves to streamline the accessibility of rotational restrictions. For any inquiries or precise details regarding particular chemical compositions, it is advisable to refer to the respective product labels.
| Herbicide | Component Herbicides | MOA | Soybean Rotational Restrictions | Notes |
|---|---|---|---|---|
| 2,4-D | 2,4-D | Growth Regulator | 7 Days = at 1 pt (0.5 lb ae)/acre 15 Days = at 2.1 pts (1 lb ae)/acre | Do not use on sandy soil, or unacceptable crop injury can occur. Seed furrow must be completely closed. |
| Expert | Atrazine, Metolachlor, Glyphosate | PS II Inhibitor, Amino Acid Synthesis Inhibitor, Shoot Growth Inhibitor | 10-18 Months | May be planted the following cropping season, but injury may occur if calcerous soil surface layers are present. If applied after June 10, rotation with crops other than corn or sorghum the following spring may result in crop injury. |
| Glyphosate | Glyphosate | Amino Acid Synthesis Inhibitor | 0 Months | When utilizing Roundup Ready® soybeans |
| Gramoxone | Paraquat | PS I Inhibitor | 0 Months | Rotational crops may be planted immediately after the last application. |
| Herbicide | Component Herbicides | MOA | Soybean Rotational Restrictions | Notes |
|---|---|---|---|---|
| Atrazine | Atrazine | PS II Inhibitor | 10-18 Months | If planted the following year, risk remains possible for crop injury when broadcast rate was more than 4 pts/acre. |
| Bicep II Magnum | Atrazine, Metolachlor | PS II Inhibitor, Shoot Growth Inhibitor | 10-18 Months | May be planted the following spring after application if average rainfall has occurred. Fields with a calcerous surface layer, or those with Bicep II Magnum applied after June 10, may experience crop injury if soybeans are planted the following year. |
| Dual II Magnum | Metolachlor | Shoot Growth Inhibitor | 0 Months | |
| Guardsman Max | Dimethenamid-P, Atrazine | Shoot Growth Inhibitor, PS II Inhibitor | 10 Months | May be planted the following cropping season, but injury may occur on soils with calcareous surface layer. |
| Linex | Linuron | PS II Inhibitor | 4 Months | See label for specific crop restrictions |
| Outlook | Dimethenamid | Shoot Growth Inhibitor | 0 Months | |
| Paramount | Quinclorac | Growth Regulator | 10 Months | |
| Prowl | Pendimethalin | Rooth Growth Inhibitor | 0 Months | |
| Sequence | Glyphosate, S-metolachlor | Amino Acid Synthesis Inhibitor, Shoot Growth Inhibitor | 0 Months |
| Herbicide | Component Herbicides | MOA | Soybean Rotational Restrictions | Notes |
|---|---|---|---|---|
| 2,4-D | 2,4-D | Growth Regulator | 1 Month | 30 day preharvest interval for sorghum |
| Aim EC | Carfentrazone | PPO Inhibitor | 0 Months | |
| Ally + 2,4-D | Metsulfuron Methyl, 2,4-D | ALS Inhibitor, Growth Regulator | 12 Months for non-STS or BOLT technology soybeans | pH 7.9 or less with average rainfall |
| Banvel, Clarity | Dicamba | Growth Regulator | Banvel = after harvest of treated crop Clarity = 4 Months | |
| Basagran | Bentazon | PS II Inhibitor | 0 Days | |
| Buctril | Bromoxynil | PS II Inhibitor | 1 Month | |
| Marksman | Dicamba, Atrazine | Growth Regulator, PS II Inhibitor | 12 Months | If applied after June 10, rotation with crops other than corn or sorghum the following spring may result in crop injury. Injury may be expected on calcareous soils. |
| Peak | Prosulfuron | ALS Inhibitor | 22 months | |
| Permit | Thifensulfuron, Halosulfuron | Amino Acid Synthesis Inhibitor | 0-9 Months | STS soybean is 0 months. All other soybeans are 9 months unless the pH is less than 7.5, then interval is 5 months. |
| Prowl | Pendimethalin | Root Growth Inhibitor | 0 Months | |
| Weedmaster | Dicamba, 2,4-D | Growth Regulator | 4 Months | |
| Treflan HFP | Trifluralin | Root Growth Inhibitor | 5 Months |