The U.S. Department of Agriculture (USDA) Animal and Plant Inspection Service (APHIS) determined Pioneer DP51291 corn is unlikely to pose a plant pest risk after reviewing public comments and prior trait approvals.
As a result, APHIS officially extended deregulation status to a new genetically engineered corn variety developed by Pioneer Hi-Bred International.
Pioneer DP51291 corn, was developed for insect resistance and tolerance to glufosinate-ammonium herbicide. The deregulation extension became effective May 19, 2026, following a federal review process that included a public comment period.
According to APHIS, the agency concluded the new variety is unlikely to pose a greater plant pest risk than a previously deregulated Pioneer corn event known as DP23211.
What the APHIS Deregulation Extension Means for Seed
Rather than conducting a completely new deregulation process, APHIS used what is known as a deregulation extension pathway. This process allows the agency to extend nonregulated status to additional plants that contain traits already reviewed and previously approved under similar circumstances.
In this case, APHIS had already deregulated the insect-resistance and glufosinate-tolerance traits in Pioneer’s DP23211 corn. Pioneer later requested that the agency extend that determination to the DP51291 variety.
As part of the review, APHIS prepared a Plant Pest Risk Similarity Assessment (PPRSA), which evaluated whether the new corn variety presented materially different plant pest risks compared to the already deregulated product. The agency concluded it did not.
APHIS published the assessment, its preliminary determination and Pioneer’s extension request for a 30-day public review and comment period before issuing the final decision.
Gene-Edited and GMO Trait Reviews Continue to Evolve
The decision reflects a broader trend within U.S. agricultural biotechnology regulation toward streamlined reviews for products that contain previously evaluated traits or mechanisms.
For seed companies and technology developers, deregulation extensions can reduce regulatory duplication and potentially shorten timelines for bringing related products to market. At the same time, APHIS continues to require scientific assessments and public transparency measures as part of the process.
The ruling also highlights the continued importance of herbicide tolerance and insect protection traits within the corn seed market, particularly as growers face increasing pressure from resistant pests, weed competition and tighter production margins.
Glufosinate-ammonium tolerance remains an important management tool in many production systems, especially as farmers seek additional herbicide modes of action to complement existing weed-control programs.
Public Comment Period Completed Before Final USDA Decision
APHIS stated it reviewed all submitted public comments before finalizing the deregulation extension.
The agency’s determination applies specifically to plant pest risk authority under the Plant Protection Act. Other regulatory considerations, including food or feed safety evaluations and international approvals, may involve separate agencies or processes depending on market destination and product use.
