In response to concerns raised by potato growers, the Michigan Department of Agriculture and Rural Development (MDARD) is proposing a permit process and is seeking feedback to ensure the long-term growth and sustainability of the potato industry while addressing how the pathogen responsible for late blight on potato, Phytophthora infestans (P. infestans), is handled in Michigan.
Potatoes are an important commodity in Michigan. The state ranks eighth in the nation for potato production with more than 80 potato growers and is the largest producer of chipping potatoes in the country. Late blight, with the ability to defoliate plants, is a significant disease for the potato industry, leading to low yields. MDARD recognizes the importance of keeping growers informed about this pathogen, and applauds researchers’ work monitoring genetic resistance and exploring means of management.
Based on the concerns raised by growers in Michigan, MDARD is seeking a solution to ensure the intentional movement of this pathogen, including in research trials, is conducted in a way that prevents any risk of unintentional spread of P. infestans spores.
Two main concerns have been identified:
• Spores can travel on the the wind and sporulate quickly on nearby hosts, resulting in the ability to travel long distances in a short timeframe. Artificially introducing inoculum while potato plants are young may result in an increased risk of infection in production fields early enough to impact yield.
• An increase in genetic variation of P. infestans in Michigan, should a different strain or mating type than those predominantly identified be introduced, could cause this devastating pest to be an even greater challenge to control.
Under Act 189 of 1931, The Insect Pest and Disease Act, Section 18(b), MDARD has the authority to require a permit for the movement of any insect or disease-causing organisms into or within the state. MDARD proposes utilizing such permits to attach conditions for any individual seeking to move P. infestans within the state. Any organization or individual must apply annually and be approved for a permit prior to any movement of P. infestans spores.
Permit conditions would include:
• A requirement that any release of spores must be delayed until a specified date that aligns with an assessment of the best time of introduction to reduce risk of substantial spread (approximately mid-August) which can be adjusted annually according to changing climate conditions.
• Limited strains and mating types—only those known to occur in Michigan will be approved.
• Limited locations where releases can occur—only those at least 30 miles away from known potato production fields will be approved.
• Required best practices for disinfection and sanitation to reduce the potential for disease transmission.
Please note any interstate movement of an insect or disease-causing organism requires a USDA-PPQ 526 permit. The USDA works alongside MDARD to ensure that 526 permits align with state regulations. If an individual or organization holds a valid 526 permit, an additional state-level permit is not required, but the above conditions will be applied via the PPQ-526 permit conditions. Intrastate movement does not currently require any permit, but this proposed process would introduce a state-level permit requirement for movement within Michigan, therefore if an individual or organization does not hold a valid PPQ-526 permit, they must apply via MDARD’s permit application.
We acknowledge that the ability to continue to conduct inoculated late blight field trials in Michigan is critical to the long-term success of the potato industry in Michigan. We welcome your feedback on this proposed change to the regulation to ensure it aligns with our shared goal of protecting and sustaining the potato industry. Your input is vital, and we encourage you to share your thoughts and insights to help shape this effort via the link provided in this email and on our website. The deadline for response is February 28, 2025. Please note: All comments received will be considered and a lack of responses will result in moving forward with the permit process as proposed here with the conditions in the attached document.
• Phytophthora infestans - Late Blight - Conditions of Permit.pdf
• MDARD Application for movement of plant pests and biological control.pdf