Best Management Practices for Pioneer® brand sunflower hybrids with the ExpressSun® herbicide tolerant trait.

Why should I use ExpressSun® herbicide tolerant technology?

Corteva Agriscience is pleased to offer our customers herbicide tolerant technology in our sunflower hybrids. The technology combines high-yielding Pioneer® brand sunflower hybrids tailored to your regional conditions with a full package of agronomic traits and tolerance to broad-spectrum herbicides, delivering efficient, season-long weed control, crop quality, and global market acceptance.

Pioneer® brand sunflowers with the ExpressSun® trait are tolerant to Express® herbicide. The hybrids have been bred using traditional breeding techniques to provide tolerance to specific herbicides.

·         The Express® herbicide system provides improved weed control over non-herbicide tolerant sunflower hybrids with traditional herbicides and gives farmers the flexibility to spray herbicides after crop emergence.

·         Express® herbicides contain actives from the Group B[1] herbicides. However, the herbicides are not interchangeable with other Group B herbicides; the correct herbicide must be used with the corresponding hybrid.

·         Express® herbicides will damage any non-herbicide tolerant sunflower hybrid.

It is imperative that good agricultural practices, the herbicide label instructions, local laws and the guidelines below are followed to preserve the efficacy of the technology and comply with all stewardship recommendations.

Management of Volunteer Sunflowers with Herbicide Tolerant Technology

As with all sunflower crops, good volunteer management is essential to avoid competitive weeds in the following crops and the build-up and spread of major diseases.

Volunteers with the herbicide tolerance traits can be controlled in crops other than sunflowers by tillage and/or any non-Group B herbicide currently registered for sunflowers. Please contact your local herbicide retailer / distributor to determine the best herbicide options available.

·         Plan at least a year ahead when planting Pioneer® brand sunflower hybrids with the ExpressSun® trait to include a diverse weed management plan and crop rotation that optimizes volunteer control in the next crop.

·         Always employ good field hygiene in and around the fields of Pioneer® brand sunflower hybrids with herbicide tolerant technology. Control volunteers in neighbouring areas and avoid field-to-field movement of seed with planting, cultivation, and harvesting equipment.

·         Prior to planting Pioneer® brand sunflower hybrids with herbicide tolerant technology, scout for volunteers and wild sunflowers in neighbouring areas. Control these by using tillage, mowing and or non- Group B herbicides alone or in a tank mix, prior to seed set.

Management of herbicide resistance in weeds

Management of herbicide resistance in weeds

The potential for weeds to develop herbicide resistance to herbicides must be considered when planning herbicide use. Herbicide resistance in weeds can develop and spread when a resistant plant reproduces and multiplies with repeated use of the same herbicide mode of action.

·         Always grow Pioneer® brand sunflower hybrids with herbicide tolerant technology in rotation with other non-herbicide tolerant crops. Use at least a 3-year crop rotation, this allows the use of alternate weed control methods, prevents build-up of volunteers, and also reduces pressure from common sunflower insect pests, diseases and Orobanche. As an additional good practice, avoid planting Pioneer® brand sunflower hybrids with herbicide tolerant technology in areas with a history of heavy infestations by wild sunflower.

·         Do not rely on Group B herbicides for weed control across the crop rotation, alternate modes of action at least 2 out of every 4 years on your fields. Using more than one mode of action herbicide in a mixture is a proven practice to delay the development of resistant weeds. To be effective in preventing the build-up of resistance, an herbicide mixture must contain active ingredients which give high levels of control of the target weed and are from different mode of action groups. Please refer to the Express® herbicide information label for more details.

·         Maintain detailed field records so that cropping and herbicide history is known.

·         Scout fields after herbicide application to detect weed escapes or shifts. If a potentially resistant weed or weed population has been detected, use available control methods to avoid seed dispersion in the field.

·         Clean equipment before moving between fields and after harvest to minimize the dispersion of weed and volunteer sunflower seed.

If you suspect a weed control failure is caused by weed resistance to an herbicide you should first contact your local Corteva Agriscience representative.



Corteva Agriscience (or its chemical company partners) shall have no liability whatsoever for any losses or damages resulting from, related to, or in connection with, (a) the use of incorrect herbicides applied to sunflower hybrids that contain the herbicide tolerant traits or (b) non-compliance with any of the other instructions set forth above, and all such liability is hereby expressly disclaimed by Corteva Agriscience and waived by you. If you have any questions on anything outlined in this document or would like additional information, please contact your local Corteva Agriscience representative.

Click here to see this translated into your language

[1]Group B herbicides, i.e. ALS inhibitors, are products based on the following chemical families: imidazolinones, pyrimidines, sulfonamides, sulfonylureas, triazolopyrimidines. For specific Group B herbicides registered for control of volunteer herbicide tolerant sunflower, please visit For more information on herbicide groups, please follow this link:



TM ® SM Trademarks and service marks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. © 2019 Corteva.