- Golden Harvest® evaluated soybean variety response to herbicides in order to understand the injury risk for a planned weed control program.
- There is potential for soybeans to experience sulfentrazone or metribuzin injury, but not all soybean varieties respond negatively to these active ingredients.
Sulfentrazone Herbicide Injury
Crop injury to sulfentrazone and other PPO herbicides (flumioxazin, saflufenacil, etc.) often occurs when the herbicide is splashed on soybean plant’s hypocotyls, cotyledons and growing points from heavy rainfall during emergence. Cool, wet and cloudy conditions following heavy rainfall will reduce the ability of the plant to metabolize the herbicide and may lead to crop injury or visual injury. Preemergence applications of a PPO herbicide may still cause hypocotyl injury, plant stunting and, if severe, growing point injury or death.
Metribuzin Herbicide Injury
Metribuzin and other triazine herbicides (such as atrazine) can cause soybean plant injury in high pH soils due to triazine herbicides being more available for plant uptake from soil. Soybean response to triazine is exhibited by interveinal yellowing or chlorosis in the lower leaves with dying or necrotic margins. In severe cases, leaves fall off the plant and sometimes result in complete plant death.
Response to Sulfentrazone and Metribuzin Herbicides
Numerous university studies have documented differing levels of soybean sensitivity across varieties from sulfentrazone and metribuzin herbicides used for soybean weed control. Each year, Golden Harvest Agronomy in Action Research screens soybean lines for sulfentrazone and metribuzin tolerance. In the trials, sulfentrazone and metribuzin are applied preemergence at 2x rates using a sandy soil with ample irrigation to amplify herbicide injury. Each variety is evaluated using a 1 to 9 scale, with 1 as most tolerant and 9 as least tolerant. The ratings are categorized into 3 groups:
- Best (ratings 1 to 2) – None to slight visual herbicide injury risk
- Average (ratings 3 to 7) – Slight to moderate visual herbicide injury risk
- Poor (ratings 8 to 9) – Moderate to high visual herbicide injury risk
Herbicide Response Ratings
A rating of Poor signifies that variety will have a higher risk of injury when weed control programs with metribuzin or sulfentrazone herbicides are planned. Injury may not be observed with normal growing conditions and rates. However, when conditions are favorable for injury (cool and wet, intense rainfall during seedling emergence, high pH soil, etc.), there is elevated potential for injury with these specific varieties. Varieties with Average or Best sensitivity ratings can be treated with herbicide safely but may still exhibit crop response levels that are unlikely to impact yield.
To learn more about how soybeans respond to herbicides, contact your local
Golden Harvest Seed Advisor.
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