Do you believe in fairy tales?

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Human beings are captivated by stories. Often, stories come with a set of lessons. We especially like to hear of great tales of bravery and magic, referred to as fairy tales. We understand that these fairy tales aren’t actually true, but deep down, we wish they were.

In the world of fungicides, there are also some common “fairy tales,” or assumptions, that lead to fungicide failure.

Here are nine false fungicide assumptions to avoid:

Generic products work equally as well as branded products.

By law, generic products have the same active ingredient as branded product formulations, but are not required to have the same inactive ingredients. Thus, one cannot expect a generic product to perform the same as a brand name product. In other cases, the amount of active ingredient in a generic product may not be the same as the amount in a branded product. Biocontrol products can also be misleading. Products like RootShield Plus or Obtego clearly identify the specific strain of Trichoderma included. Other products that may have Trichoderma species do not identify the exact strain, and sometimes the strains aren’t even alive. This can cause inconsistent results.

All fungicides in a FRAC group are equal and lead to the same results.

Although fungicides that belong to the same FRAC group have a similar mode of action, they can target different pathogens and their spectrum of activity can vary greatly. Some FRAC groups have products that act very differently in the plant. Strobilurins (FRAC 11) are a great example. Some are actively systemic and others are more active on the plant surface. In other FRAC groups, like SDHI’s (FRAC 7), the active ingredients can be a broad spectrum (like fluxapyroxad or fluopyram) or very narrow spectrum (like isofetamid and Botrytis control).

Using products together means you can use lower rates of each.

Even if there are two fungicides targeting the same pathogen (i.e., Subdue + Adorn), they should still be used at the labeled rate. Testing these products alone and in combination has clearly shown that the lowest label rate is necessary to achieve control. They don’t have additive qualities, but may help reduce the chance of resistance if tank-mixed with other products in different FRAC groups.

Rescue treatments are successful — it’s never too late.

Any grower who has dumped plants knows that sometimes it is just too late. The most cost-effective way to manage all plant diseases is prevention. More often than not, plants do not recover from disease unless they are treated in the early stages. In some cases, the diseases are very hard to control even when products are applied preventatively. Diseases like powdery mildew, for example, can be treated effectively in the early stages of growth but are impossible to stop once they reach a certain point.

There is at least one effective product for all diseases.

Certain viruses, bacteria and fungal diseases still do not have a cure or are extremely difficult to control. There is also no single product that works on every disease.

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Diseases can be identified by sight alone.

Symptoms caused by plant pathogens are not easy to diagnose, so we recommend having a diagnostic lab to confirm diseases. Misdiagnosis can lead to application of the wrong pesticides, which will cost you time and money. Some issues, like root rot, can be caused by unrelated fungi and bacteria. In many cases, more than one pathogen is involved and telling them apart by sight isn’t possible. If a plant has both fungi and bacteria, treating only one will not address the other problems.

Increasing the rate of a fungicide will improve its control.

The rate range of a fungicide is researched for years under many different conditions before a product is launched. Trials take place over many years, and they often include very high rates to determine phytotoxicity potential. We have found that some fungicides don’t work as well at higher-than-labeled rates. In some cases, higher application than recommended can harm the plant. The old “more is better” rule is not a reliable one.

Using a fungicide more often than labeled will improve control.

Directions on the label are science-based and, if followed properly, should provide results consistent with claims that are on the label. Trials of many products have shown that sometimes using something too often may make the disease worse. It can cause stress on the plant, making it more susceptible to disease. Simply adding more water to the leaves (sprays) or roots (drenches) could result in conditions that favor the disease. Adding too much fungicide can cause phytotoxicity that results in entry points for certain pathogens.

Alternating highly effective products with less effective products is a good strategy.

You want to choose products that have been proven to be effective and are backed by research-based results. Research really has shown that alternating an effective product with nothing is better for disease management than using something that sort of works.