Rotating Ornamental Fungicide Premixes for Fun and Profit
August 2, 2021 I am frequently asked for fungicide programs for specific needs, and sometimes as a means to prevent all diseases on all plants. The number of products in general that are available for the ornamental industry increases every year, and deploying them effectively is a very complex problem.
One of the most complex groups is the FRAC 7 and FRAC 11 premixes that are now available in at least four different combinations. There are also older products of other FRAC groups including Junction (SePRO), Concert II (Syngenta), Palladium (Syngenta), and Orvego (BASF). We even have a new premix coming with a FRAC 3/7 blend from Syngenta when EPA gets back into action.
The idea that you can use a premix to prevent resistance development in some pathogens, or broaden your ability to control many pathogens in a single product, make these products very attractive.
For a large range of diseases, each 7/11 premix works very well to excellent, or at least more or less the same, giving none of them an edge. These diseases include Alternaria, anthracnose, black spot, Botrytis, Cylindrocladium, powdery mildew, Sclerotinia, and Rhizoctonia. In other cases, a premix like Junction or Concert II may provide both bacterial and fungal foliar disease control.
Rotation Strategy
Since there are so many 7/11 premixes, you must be careful about choosing a product for an effective rotation. Just because the exact active ingredient is not the same does not mean you can rotate between two FRAC 7/11 premixes. You have to recognize that other FRAC 11 products (like Heritage/Syngenta and Empress Intrinsic/BASF) cannot effectively be rotated with a 7/11. Additionally, you cannot rotate products that are FRAC 7 (like Astun/OHP). For certain pathogens, such as Alternaria leaf spot, powdery mildew, and Botrytis, a rotation of a 7/11 with Palladium (9/12) is very effective.
In some cases, we only have a single representative of a FRAC group, like cyprodinil (FRAC 9) in Palladium. That means alternating with anything except Medallion (the other part of Palladium – FRAC 12). Another example of this type of situation is seen with the premix of dimethomorph (FRAC 40) and ametoctradin (FRAC 45), which are the components of Orvego. This premix is extremely effective for Phytophthora and downy mildew. Any rotation with another downy mildew or Phytophthora fungicide except Micora (Syngenta, another FRAC 40) or Stature (BASF, dimethomorph) will be safe.
Our real difficulty in choosing the right rotation for the very popular 7/11 group (Broadform, Mural, Pageant Intrinsic, and Orkestra Intrinsic) is that they are so effective and so very broad-spectrum that any effective rotation with another premix would avoid any product with a FRAC 7 OR FRAC 11. The table below shows some possible premix fungicides that could be rotated with a 7/11 fungicide.
Considering premixes and stem/root diseases is simpler. There are really only a few that are used, including Banrot. The 7/11 premixes that are registered currently for drenching are Pageant Intrinsic, Orkestra Intrinsic, and Mural. While they are broad-spectrum, we often use other products for root disease control.
Know Your Costs
The examples I give are just examples and not suggestions. You should choose your premixes carefully based on your crops and diseases, what is legal for your use site, and what makes sense financially for your greenhouse.
You can also fall back to the primary way you choose a fungicide: cost. Be sure, however, to check real cost and not container cost. Real cost involves knowing the effectiveness, interval, safety, and use rates. The use rates do differ, and in some key diseases, using the most effective product is the difference between success and failure. Overall, premixes are all very good products for ornamentals.
Fungicide Premix Options
The table below shows some possible premix fungicides that could be rotated with a 7/11 fungicide.| Disease | Best 7/11 for This Disease | Best Premix Rotation | FRAC Groups |
|---|---|---|---|
| Alternaria | Any of them | Concert II (nursery), Palladium | 3/M5, 9/12 |
| Anthracnose | Pageant Intrinsic, Broadform | Concert II (nursery) 3336, OHP6672 | 3/M5, 1 |
| Bacteria | None | Junction, Postiva | M1/M2, 3/7 |
| Botrytis | Broadform, Orkestra Intrinsic | Palladium | 9/12 |
| Downy mildew | Mural | Orvego | 40/45 |
| Fusarium | Orkestra Intrinsic | Terraguard, Medallion | 3, 12 |
| Powdery mildew | Broadform | Palladium, Any FRAC 3 | 9/12, ,3 |
| Rust | Mural | Any FRAC 3 | 3 |
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