Fungicide resistance or reduced efficacy is a concern when managing peanut diseases, especially the foliar diseases early and late leaf spot. Managing these concerns requires an integrated approach with constant monitoring of the product’s efficacy and application programs to avoid resistance selection.
Two common resistance management strategies are alternating (or rotating) and mixing fungicide product modes of action (MOA). It has been indicated that MOA mixtures are a more sustainable strategy for resistance management than alternating, but they may be costlier as they tend to increase the spray program’s number of fungicides.
So, it is important to understand the value of these two strategies especially when using products that have a moderate to high risk for resistance selection.
Identifying the pathogen population present is a key component when assessing these two strategies. Location populations varied with late leaf spot being the primary pathogen in Marianna, and early leaf spot in Citra (Fig. 2). It is also important to note that significant pressure was also present from late leaf spot and rust in Citra as well.
Mixing fungicide MOA appears to be the optimal strategy for disease control, yield savings and managing fungicide resistance. However, alternating MOA is also a successful strategy, but its efficacy appears to be highly dependent on the pathogen populations present. Regardless of the strategy chosen, disease control and yield savings were improved with these strategies compared to the untreated plots.
AgFax Weed Solutions
Both strategies will help sustain the efficacy of a fungicide product, and if cost is an issue then alternating modes of action in a program is better than repeated applications of a product alone. It should be noted that when using generic products like these, the average cost only varied by approximately $2.50 per acre.
The cost of mixtures will depend largely on the mixing partners used, and with some planning these costs can be minimized.
Fungicide resistance management should be an important component of any peanut disease management program. More information about fungicide resistance and its management can be found in this UF/IFAS publication, Fungicide Resistance Action Committee’s (FRAC) Classification Scheme of Fungicides According to Mode of Action, or by contacting your local extension office.