By Scout Nelson
The Environmental Protection Agency (EPA) has granted special approval for the use of malathion in South Dakota to control red sunflower seed weevils. This approval is effective every year from July 15 to August 31 until 2030, unless revoked earlier. Outside this time frame, malathion cannot be legally used for sunflower weevil control.
This decision comes in response to rising weevil populations in South Dakota that no longer respond to commonly used pyrethroid insecticides. Testing has shown resistance to active ingredients such as lambda-cyhalothrin, esfenvalerate, and others. Also, chlorpyrifos, once used for this pest, is no longer approved for use on sunflowers.
The approved malathion products for use include:
- Malathion 5
- Fyfanon Malathion Insecticide
- Malathion 57 EC
- Malathion 5 EC
It’s important to note that this special label only applies within South Dakota. North Dakota has not reported similar resistance issues.
The South Dakota Department of Agriculture and Natural Resources worked closely with the National Sunflower Association to obtain this temporary approval.
Malathion is an organophosphate insecticide that works by stopping a key enzyme in insects. It has been used in South Dakota for other pest issues for years.
Farmers planning to use malathion must follow several key steps:
- Only apply during approved dates
- Ensure sunflowers are at least 10% in bloom
- Follow the red sunflower seed weevil threshold
- Avoid harming bees—apply only between 12 a.m.–9 a.m. or 6 p.m.–12 a.m.
- Respect buffer zones in select counties to protect endangered butterflies
By following these guidelines, farmers can protect sunflower crops while staying within safety and legal limits.
Photo Credit: sunflowers-no%20source
Categories: South Dakota, Education, General, Rural Lifestyle