As the growing season winds down and planning begins for next year, turf managers often look back on the challenges that caused the most frustration. While attention naturally turns to the diseases you will likely face again next season, don't overlook the importance of evaluating how they were managed this year.
Declining performance in trusted chemistries is not always the result of application timing or environmental conditions. In some cases, it may be an early warning sign of fungicide resistance. Before EOP closes, it is worth making sure you've covered all your bases when it comes to fungicide rotation and resistance management in your program.
Recognizing Signs of Resistance
Resistance rarely appears overnight. It develops as a gradual decline in fungicide performance. A product that once delivered three weeks of control may now provide only two. Disease outbreaks occur earlier than anticipated, and products that were once highly reliable no longer perform at the same level.
When this happens, the temptation is to shorten intervals, increase rates, or make additional applications. While those adjustments may provide short-term relief, they can further increase selection pressure if the same mode of action is used repeatedly. When a small portion of the pathogen population survives a fungicide's mode of action, repeated exposure can gradually shift the population toward reduced sensitivity.
Several important turfgrass pathogens have documented fungicide-resistant populations, including Clarireedia spp. (dollar spot), Pythium aphanidermatum (Pythium blight), and Colletotrichum cereale (anthracnose). The presence of resistant pathogen populations highlights the need for fungicide stewardship to maintain long-term effectiveness of these chemistries.
Keep Your Tools Sharp
Each fungicide is a valuable tool, but overreliance on the same chemistry can gradually dull its effectiveness. Responsible resistance management helps preserve the performance of the products you depend on, ensuring they remain reliable when needed most.
Key principles of responsible resistance management include:
Long-term success comes from combining multiple strategies that reduce reliance on any one mode of action. By building diversity into your program, you can protect the performance and longevity of each fungicide in your toolbox.
New Chemistry Creates Opportunity
One of the most effective ways to strengthen resistance management is by incorporating different modes of action. New modes of action add flexibility to rotation plans, helping diversify disease management strategies and reduce dependence on a limited number of chemistries.
Expanding the number of available fungicides creates more flexibility in rotation plans, allowing turf managers to vary modes of action while reducing the risk of over-reliance on a limited set of products.
Final Thoughts
The goal of a fungicide program isn't just to control disease today. It should also preserve effective disease management options for the future.
Before finalizing next year's program, evaluate whether your rotation strategy, modes of action, and resistance management practices are working together to protect the chemistries you rely on most. Small adjustments made during the planning process can help reduce resistance risk and maintain consistent performance throughout the season.
Resistance management starts long before resistance becomes visible. The decisions you make today can help ensure your most valuable fungicides remain effective for years to come.
