Now that the rains are here, we are expecting a rise in fungal infections. Without proper management, there is a likelihood of resistance growing. But of course that won’t happen because you are going to be proactive, right? Like we said before, for disease to actually happen three factors actually need to be present. The disease causing organism, the environment to enable it and the actual plant that is susceptible to the microorganism. Of the three factors, you can be proactive with the last two which is the environment an the plant itself. If a specific fungus cause’s havoc year after year, Fungi thrives where there is moisture and humidity. With the rains, it is impossible to avoid the foliage being wet; however you can take measures to reduce humidity by proper spacing etc. You can read more about it here:
But the whole purpose of this article is to know how to effectively treat fungal infections, and avoid a resistance forming, which will take your cost of production over the roof if you are not careful.
- Select and use fungicides correctly.
For this you want to make sure that you choose a fungicide with an active ingredient that has been proven useful against the fungus. If you are not too sure or you think you may be suffering from more than one fungus, you could mix fungicides that have different modes of working just so you make sure you are completely covered. This can be done through premixes. Pre-mixes are combinations of two or more fungicides applied as a single mixture. Tank-mixing allows for adjusting of the ratio of fungicides to fit local conditions. The combination, if composed of a high-risk (single-site) fungicide with a low-risk (multisite) fungicide will contribute to resistance avoidance. The different fungicides in the mixture must be active against the target fungi.
- Rotate fungicides with different mechanisms of action, not just different label names.
Rotating fungicides involves alternating products so that you avoid back-to-back treatments with any one single-site fungicide or fungicides with a medium to high risk of resistance.
Note: read fungicide labels to determine if any fungicides cannot be mixed or rotated together. There are often limits on the total amount to be applied, the number of allowable applications per season, and restrictions on back-to-back applications.
- Apply the correct rates with proper coverage of the foliage to produce good disease control. For some fungal infections, you may need to also spray the bottom side of your leaves for the coverage to be enough.
- If appropriate, use a seed or soil fungicide treatment. For crops like potatoes you can inoculate your seeds which ‘provides immunity’ against pathogen while simultaneously reducing risk of resistance.
After application, monitor the field to determine how well the fungicide worked and for signs of any failure. This will inform your decision of whether you need to incorporate a different type of fungicide while the fungus is still suppressed as opposed to letting the infection become full blown again.