Maintain quality without losing tools from the disease toolbox
February 7, 2023
Foliar pathogens can ruin an otherwise marketable crop. In vegetables, Stemphylium, anthracnose, Alternaria, early blight, and gummy stem blight are some of the usual suspects.
Multiple sprays per season are often required to fend off these foliar leaf spot pathogens. Integration of multi-site chemistries (such as Bravo® ZN, manzate, and Captan) has been critical to spray programs, providing broad-spectrum control and low resistance risk. In fact, without knowing it, many growers have delayed pathogen resistance to newer, single site products by using multi-site chemistries.
However, recent re-evaluation decisions from the Pest Management Regulatory Agency (PMRA) have left fewer broad-spectrum multi-site crop protection applications available for vegetables. Now, careful consideration must be given to a crop protection program to grow a successful crop and keep disease management tools in the toolbox for the long term. This may seem daunting, but a few considerations will go a long way.
What is meant by “know your groups”?
The Fungicide Resistance Action Committee (FRAC) has a great explanation of fungicide classification and modes of action. Watch this short clip on codes and labelling.
For example, on the top of the Miravis® Duo label, you can see that it contains a Group 7 and Group 3 fungicide.
You know the code. Now what?
The best long-term strategy is loss prevention – keeping the tools around for as long as possible. But how?
- Know your groups
- Plan accordingly
- Participate in monitoring programs
Here is another short video from FRAC, this time highlighting the general best practices to help delay fungicide resistance.
Putting it all together: What are the codes, risks, crops and foliar recommendations?
| Switch® | Miravis® Duo | Quadris Top® | Aprovia® | Allegro® |
|---|
| FRAC code | 9 | 12 | 7 | 3 | 11 | 3 | 7 | 29 |
| Resistance risk | Medium | Low to medium | Medium to high | Medium | High | Medium | Medium to high | Low |
| Ginseng | 0.31 to 0.39 kg/acre | 0.4 L/acre | NR** | NR** | 0.485 L/acre |
| Tomato | 0.39 kg/acre | 0.4 L/acre | 0.25 L/acre | 0.2 to 0.3 L/acre | NR** |
| Pepper | 0.31 to 0.39 kg/acre | 0.4 L/acre | 0.25 L/acre | 0.2 to 0.3 L/acre | 0.7 L/acre |
| Brassica | 0.31 to 0.39 kg/acre | 0.31 to 0.4 L/acre | 0.28 to 0.4 L/acre | NR** | NR** |
| Onion | 0.31 to 0.39 kg/acre | 0.4 L/acre | 0.28 to 0.4 L/acre | 0.3 L/acre | 0.46 L/acre |
| Cucurbit | NR** | 0.4 L/acre | 0.28 to 0.4 L/acre | 0.2 to 0.3 L/acre | 0.35 to 0.7 L/acre |
| Guidelines | Group 3: Alternate or mix with an effective fungicide in another group. Group 7: No more than 33% of the total number of fungicide applications per season when applied as a solo fungicide, and no more than 50% of the total number of fungicide applications per season when applied in a mixture (with an effective partner in a different group). Always alternate with a different group when applied as a solo product, and make no more than two consecutive applications when applied in a mixture Group 9: Total applications per season should not be more than 50% of the total; see FRAC guidelines for specific recommendations on Botrytis. Group 11: Applications in mixtures are strongly preferred and total applications in a mixture (with an effective partner in a different group) per season should not be more than 50% of the total; see FRAC website for specific guidelines for cucurbit and tomato crops. Group 12: Total applications per season should not be more than 50% of the total, up to two consecutive applications when applied in a mixture (with an effective partner in a different group); see FRAC guidelines for specific recommendations on Botrytis. Group 29: Alternate or mix with an effective fungicide in another group; for high-risk pathogens, total applications per season should not be more than 50%. Applications in a mixture are preferred but if applied solo, alternate with a different mode of action. |
*Review label for full understanding of rate required for crop-pathogen combination.
**NR: The product is not registered in the crop listed. For resistance management, planning means considering the general guidelines from FRAC for resistance management for each group. These indicate specific practices like how many applications can be made each year, if those should be in alternation or in a mixture, and what proportion of the total planned sprays can include a specific group. Note that for some crops, pathogens, or crop-pathogen combinations that are considered high-risk, there are specific guidelines that should be followed to delay resistance. Plus, remember to consider pre-harvest intervals, restricted entry intervals, maximum applications per season on the product label, and other label restrictions, which vary crop by crop.
Does this seem overwhelming? Reach out to your Syngenta rep or retail partner if you’d like advice on building a crop protection program with resistance management top of mind.
Please check with your exporter when using any Syngenta product on ginseng destined for use outside of Canada. At time of print, Maximum Residue Limits (MRLs) had been established for the active ingredients cyprodinil, fluazinam, and pydiflumetofen for export markets in the United States and fludioxonil for export markets in the United States and Codex. Please see the Bryant Christie Inc. Global MRL database at https://www.globalmrl.com/db#query for a complete list of MRLs. Should you need additional information on export market MRLs, please consult with Syngenta to receive the most up-to-date information.
Always read and follow label directions. Aprovia®, Bravo®, Miravis®, Quadris Top®, Switch®, Inspire Super® and the Syngenta logo are trademarks of a Syngenta Group Company. Allegro® is a trademark of ISK Biosciences Corporation.
