What Is Fungicide and How Do I Use It?

A fungicide is a type of pesticide designed to prevent, inhibit or control the spread of fungal plant diseases. Once active, many fungal diseases cannot be killed or controlled by fungicides. Fungal plant diseases are best managed through good cultural practices and proactive fungicide treatments. These treatments are typically done when there is evidence of fungal disease or as a preventive measure during specific seasons or weather conditions. 

What is Fungus?

First of all, what exactly is fungus? According to Merriam-Webster Dictionary, fungus is defined as, “any of a kingdom (Fungi) of saprophytic and parasitic spore-producing eukaryotic typically filamentous organisms formerly classified as plants that lack chlorophyll and include molds, rusts, mildews, smuts, mushrooms, and yeasts.” As noted in that definition regarding the lack of chlorophyll, fungi differ from a plant in that they require a host and do not undergo photosynthesis. Instead, fungi actually thrive in dimly lit conditions. Fungi spread through spores and typically thrive in environments with poor airflow, excessive moisture, and low light conditions. This is why after a rainstorm, where clouds are prevalent and grounds are wet, you may notice signs of fungus. According to Graham Simmons, Director of Turf Grass Operations for Woerner Farms, ”Rainy and cloudy weather are prime conditions for fungus.”

Just like bacteria and insects, there are harmful fungi, but there are also beneficial fungi. According to Mr. Simmons, some of the harmful fungi can cause various effects ranging from an unsightly lawn to a lawn decline and potentially death. On the flip side, in conjunction with soil bacteria, they can contribute to organic matter and break down harmful substances in the soil. To protect the beneficial fungi in your soil, Mr. Simmons primarily recomments a holistic approach to rid your lawn of fungal disease. “The best practice is to take a multi-step approach and not rely exclusively on chemicals. If there is a way to prune some bushes to create better airflow or prune a tree to provide more sunlight, do that in conjunction with fungicide treatment.”

What kinds of fungicide treatments are there?

Fungicides are obviously the most common treatments and they come in two kinds: preventative and curative. Preventative fungicides are sprayed before the appearance of fungus to prevent fungus from growing. Curative fungicides are sprayed after the fungus has attacked your lawn and are relatively effective in eliminating fungus.

These treatments come in another two forms: contact and systemic. Contact treatments work on whatever it sticks to once sprayed. Systematic treatments, as Mr. Simmons refers to as the better option, is absorbed by the plant and then translocated throughout the plant. Mr. Simmons cautions against repetitive use of fungicides saying, “When applying fungicides you do not want to spray the same one back to back to back, rotate your mode of action so you do not build up a resistance in the fungus. Just because you applied the product and it cured it, it is not a good thing to spray the same spot.”

The timing of this treatment  can vary depending on the region, climate, and the specific type of fungus you’re dealing with. Here are some general guidelines:

1. Identify the signs of fungal disease: Look for symptoms such as brown patches, yellowing grass, thinning areas, or the presence of fungal growth like mushrooms or powdery substances on the grass blades.

2. Timing for preventive fungicide application: If your lawn is prone to fungal diseases or if you live in an area with a history of fungal problems, you can apply a preventive fungicide in early spring or fall before the disease typically becomes active. Consult with a local gardening expert or extension service to determine the best timing for your specific region.
3. Curative fungicide application: If you notice signs of a fungal disease in your lawn, such as the ones mentioned earlier, it’s important to act promptly. Apply the appropriate fungicide as soon as you identify the problem. Different diseases may require different types of fungicides, so be sure to choose the right one for the specific fungal infection affecting your lawn.

4. Follow the fungicide label instructions: Read and follow the instructions provided by the fungicide manufacturer carefully. It will provide information on the appropriate application rates, timing, and safety precautions. Make sure to wear protective clothing, such as gloves and a mask, when applying fungicides.

5. Consider weather conditions: Fungicides are most effective when applied under favorable weather conditions. Typically, it is best to apply fungicides when the weather is dry and calm, without strong winds or rain in the forecast. Rain immediately after application can wash away the fungicide, reducing its effectiveness.


Soil Health is Key

As previously mentioned, soil health plays a major role in preventing these problems in the first place. Mr. Simmons explains, “Anything that will do damage to your yard is going to have a better chance at doing it if your lawn is unhealthy. By maintaining a healthy soil, your lawn will be less susceptible to disease, and it will be set up better to recover from it. General soil health which equates to plant health means that you should see less chance of disease and a quicker recovery.” Proper lawn care practices, such as regular mowing, adequate watering, proper fertilization, and testing with SoilKit can reduce the risk of fungal diseases. If you’re unsure about the specific type of fungus affecting your lawn or the appropriate fungicide to use, reach out to us at SoilKit through an ASK the Expert consultation.

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