Fungicide & Spray Decision Database

You choose the crop and the disease, and the tool filters the registry to the products labelled for that exact crop–disease pairing. It then ranks them by their land-grant efficacy rating on the 0–4 scale (4 = very good/excellent), breaking ties first by avoiding a repeat of your last FRAC mode of action and then by the shortest pre-harvest interval. The top of the list is the highest-efficacy, rotation-friendly, earliest-to-harvest option.

FRAC is the Fungicide Resistance Action Committee, which assigns every fungicide a numeric code by its mode of action — for example QoI strobilurins are FRAC 11, SDHIs are FRAC 7, DMI triazoles are FRAC 3. Fungi develop resistance to a single mode of action fast if it is used repeatedly, so the rule is to rotate FRAC groups between sprays. The tool flags when your top pick repeats the FRAC group you sprayed last.

The PHI is the minimum number of days that must pass between the last fungicide application and harvest, set on the product label so residues fall to legal limits. It varies widely — chlorothalonil on tomato can be 0 days while a strobilurin on wheat may be 40 days. The tool shows each product's PHI and reports the earliest harvest date the top pick allows.

In this database the highest-rated wheat stripe-rust option is a prothioconazole + tebuconazole premix (FRAC 3, DMI triazoles) at about 4.0–5.7 fl oz/acre, efficacy 4/4, with a 30-day PHI. A pyraclostrobin strobilurin (FRAC 11) rates 3/4. Rotate the triazole and strobilurin modes of action across sprays rather than repeating either.

Late blight is an oomycete, not a true fungus, so CAA chemistry like mandipropamid (FRAC 40, efficacy 4/4) is the strongest rated option — about 5.5–8 fl oz/acre on tomato with a 4-day PHI. Anchor or alternate it with a multi-site protectant such as chlorothalonil (FRAC M05) or mancozeb (FRAC M03), which carry very low resistance risk.

Single-site fungicides (FRAC 3, 7, 11 and similar) hit one target in the pathogen, so they are powerful but at high or medium resistance risk — they must be rotated. Multi-site protectants such as mancozeb (M03), chlorothalonil (M05) and copper (M01) attack many sites at once, are at very low resistance risk, and are ideal anchors or tank-mix partners to protect the single-site products.

Land-grant universities publish consensus efficacy tables using a 0–4 scale: 0 means not effective or not labelled, 1 poor, 2 fair, 3 good, and 4 very good to excellent. The ratings reflect field-trial performance against each specific disease, which is why the same active ingredient can rate 4 on one disease and 2 on another. This tool uses those ratings to order the options.

No — that is the fastest way to lose the product. Repeated use of one mode of action selects for resistant strains of the pathogen, and high-risk groups like QoI (11) and SDHI (7) have already failed on several diseases where they were over-used. Rotate FRAC groups every spray and keep a multi-site protectant in the program; the tool's rotation light warns when your pick repeats your last group.

Within the labelled range a higher rate can lengthen protection on heavy disease pressure, but exceeding the label is illegal and does not overcome resistance — a resistant population is unaffected by more of the same chemistry. The right move under pressure is the correct labelled rate of an effective mode of action, applied with good coverage and timing, then rotated. Use the rate range shown as your legal envelope.

No. The label is the legal authority for crop registration, rate, PHI, re-entry interval and use restrictions, and it can differ by region and formulation. This database gives efficacy-based selection guidance from FRAC codes and land-grant tables to help you choose, but you must confirm every figure against the actual label you hold before spraying.

Set the FRAC group you sprayed last in the input. The tool then marks each product with a coloured light: green means a different mode of action (safe to rotate to), amber means the same chemical family, and red means it repeats your last FRAC group. If the top pick lights red, choose the best green-lit option below it instead — that is the rotation working in your favour.