FRAC Rotation & MOA Groups & Compliance

Resistance is when a fungal population evolves to survive a fungicide that once controlled it, usually because the same mode of action (MOA) is used repeatedly. FRAC — the Fungicide Resistance Action Committee — groups fungicides by MOA and assigns each a code. Rotating between different FRAC groups, and capping how often any one group is used, slows resistance. This tool checks how many groups your season needs.

From your total sprays and the label cap on consecutive sprays per FRAC group, the tool finds how many distinct mode-of-action groups you must rotate through to cover the season without exceeding any group's limit. So 8 sprays with a cap of 2 per group needs at least 4 different MOA groups. It then flags whether the groups you have on hand are enough to stay compliant.

Because relentless use of one MOA is the fastest route to resistance — survivors multiply until the product simply stops working, sometimes permanently for that whole chemical group. Labels and FRAC guidelines therefore cap consecutive applications and total uses per season, forcing rotation so no single mode of action carries the whole disease-control load.

It is the maximum number of back-to-back applications of the same FRAC group allowed before you must switch to a different mode of action, set by the product label and resistance guidelines. Common caps are one or two consecutive sprays, or a fixed share of total sprays. Entering your cap lets the tool size the rotation and the number of distinct groups required.

Tank-mixing or using a pre-mix of two effective MOAs is a recognised resistance-management tactic and can substitute for some rotation, because the fungus must overcome two modes of action at once. But it does not remove the need to vary chemistry over the season. Treat a mix as one application that draws on its component groups, and still aim to rotate across the program.

If the distinct MOA groups available are fewer than the season needs, you cannot fully comply with the caps — you would have to over-use a group and accelerate resistance. The tool flags this so you can source additional effective modes of action, reduce spray numbers through better timing and forecasting, or add cultural and resistant-variety controls to cut reliance on chemistry.

Every fungicide label and most product databases list its FRAC code or group number, which identifies the mode of action. Build your program by listing the FRAC group of each product you plan to use, then ensure consecutive sprays come from different groups. Products sharing a FRAC code count as the same MOA even if the brand names differ.

Yes — the rotation logic is universal: any spray program, on any crop, against any fungal disease, benefits from rotating modes of action within label caps. Just enter your total planned sprays and the consecutive cap that applies, and the tool tells you the MOA groups needed and whether your plan is compliant.

They are a planning guide to rotation, not a substitute for the label. Real programs must follow each product's specific consecutive-use and total-use limits, pre-harvest intervals and local resistance-management guidelines, which can be stricter than a single cap. Use the output to design the rotation, then confirm every application against the actual labels.