21: 05: 2026
Regulatory pressure on long-standing multisite fungicides is reshaping the landscape of plant disease control and resistance management. As products such as chlorothalonil and mancozeb face tightening restrictions, growers are being forced to rethink disease-management programs that have relied on these foundational chemistries for decades.
Regulatory Shifts Challenge Resistance Management
Effective resistance management in plant disease control has traditionally depended on multisite fungicides, which offer broad-spectrum protection and lower resistance risk when used in rotation or mixtures with single-site modes of action. However, regulatory uncertainty surrounding key protectants such as chlorothalonil and mancozeb is narrowing the toolbox available to growers.
According to the National Potato Council (2024), restrictions on chlorothalonil could significantly disrupt potato production systems. In feedback to the U.S. Environmental Protection Agency (EPA), some growers warned that production costs could rise by as much as 300% under proposed scenarios. Others indicated that they would only be able to sustain meaningful resistance management efforts if mancozeb use limits remain unchanged.
As of September 2024, the EPA proposed canceling mancozeb use in grape production because of potential post-application worker health hazards, according to the National Grape Research Alliance. This proposal has fueled broader concern that mancozeb’s future availability in other agricultural sectors may also come under scrutiny.
Meanwhile, the Interim Decision on chlorothalonil, which took effect in December 2024, identified maximum annual rate reductions across multiple crops and agricultural use sites. The EPA is currently reviewing label amendments that will formally reduce chlorothalonil seasonal use limits to 6.5 lb/acre, to be implemented no later than 12 months after the revised labels are stamped and approved.
Although no official phase-out date has been announced, some industry observers believe that 2027 could be the final season in which chlorothalonil is used under current labelling.
Rethinking Programs Under High Disease Pressure
In regions with high disease pressure, growers need dependable tools that enable them to suppress disease without accelerating resistance development. The impending label changes for chlorothalonil and ongoing scrutiny of mancozeb mean that disease-control programs built around these products will require adjustment.
With new use-rate restrictions rapidly approaching, growers are encouraged to plan fungicide programs that reduce reliance on chlorothalonil and mancozeb, while still preserving multisite activity within their resistance-management strategies.
Innovation in Focus: Curezin® from VM Agritech
One notable R&D response to these pressures is Curezin®, a new broad-spectrum fungicide/bactericide from VM Agritech, which received EPA registration in August 2025 and is now available in 47 U.S. states.
Curezin is a patented liquid copper and phosphorous acid technology that delivers broad-spectrum disease suppression through combined multisite modes of action (FRAC M01 and P07). This dual mechanism is designed to integrate smoothly into modern fungicide programs that must balance efficacy, resistance management, and evolving regulatory requirements.
In addition to its disease-control properties, Curezin contains zinc micronutrients, making it a 2-in-1 solution that supports both plant nutrition and disease management. When integrated into rotation, tank mixtures, or preventative programs dominated by single-site fungicides, Curezin has demonstrated strong performance in reducing pathogen populations and enhancing overall program robustness.
Field Data: A Potential 1:1 Replacement
In a 2025 potato early blight trial in North Dakota, a grower-standard program incorporating both chlorothalonil and mancozeb was compared with two alternative programs:
1. A program in which chlorothalonil was replaced by Curezin, and
2. A program in which mancozeb was replaced by Curezin.
All three programs delivered equivalent levels of disease suppression, indicating that Curezin can function as a 1:1 replacement for these multisite fungicides within a structured program.
Beyond disease control, multiple trials and commercial demonstrations have reported substantial yield gains, particularly where Curezin is applied in-furrow. These results position the product as a strong candidate not only for resistance management, but also for improving economic returns under real-world production conditions.
Ongoing R&D and Future Outlook
The VM Agritech R&D team is extending its work into the 2026 season, focusing on refining recommendations that balance cost effectiveness, program efficiency, and long-term resistance stewardship. This includes defining optimal timings, rates, and integration strategies with existing fungicide portfolios.
As regulatory pressures continue to reshape fungicide availability, technologies like Curezin represent a new generation of multisite tools that can help:
• Restore resilience to disease-management programs,
• Support sustainable fungicide stewardship, and
• Provide growers with more flexibility in the face of evolving label constraints.
In an era where traditional multisite standards are increasingly under pressure, ongoing innovation from R&D pipelines will be critical to maintaining effective, sustainable, and economically viable disease-management strategies for growers worldwide.