What Causes Fungus in Grass?

There are several causes of lawn fungus, most of which are just a result of poor lawn care practices.

Below I provide more details on each cause, with my experience treating the fungus for each scenario.

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1. Excessive heat and humidity

To reiterate, fungus appears when your lawn is under stress, such as if you overwater it (even with excessive rain) or if you underwater it and/or during times of drought.

Heavy irrigation and prolonged periods of rain leave water on the surface of grass leaves. Mycelia (root-like structures of a fungus) use this accumulated water as a pathway to travel from leaf to leaf, spreading the fungus along the way.

Using your lawn mower or even walking on your lawn when you are fighting fungus can help spread the fungus throughout your lawn.

2. Malnutrition

As a homeowner, you probably already know proper fertilization practices, but many of us still make the big mistake of over- or under-fertilizing, resulting in brown edges and/or fairy ring disease.

A general rule is to apply nutrient-rich fertilizer 4 times a year to the lawn. However, it is important to perform a soil test to Determine the proper amounts of nitrogen fertilizer or other types of nutrients for your lawn. But be sure to perform a soil test first before applying any fertilizer. fertilizer for your lawn.

And remember, fertilizer isn’t the only source of nutrients for your lawn. There’s also rainwater or water from sprinklers that helps the grass absorb essential nutrients like nitrogen that’s already present in the soil.

The faster nitrogen is used up when it rains or when you water it, the faster it will need to be replenished or you will develop fungus on your lawn.

3. High night temperatures

If nighttime temperatures are as high as daytime temperatures in your area, this could encourage the development and proliferation of fungi in your lawn.

While there is not much you can do in this situation and I cannot advise you to water your lawn at night as this can provide the right conditions for fungus to grow, you should keep in mind that this could be a possible reason for fungus growth on your lawn.

4. Poor airflow

Lawns with poor or restricted airflow are more likely to develop fungus. Good airflow reduces moisture levels much faster than stagnant air.

Poor air circulation can be caused by nearby privacy fences, buildings and dense trees and can increase fungal activity on lawns, surrounding garden sheds, above ground pools and outdoor furniture.

5. Compacted soil

Compacted soil affects the flow of water that penetrates the roots, which can cause root diseases, including fungal growth.

In addition to an infected lawn, soil compaction can also result in a weak, thin lawn that is prone to weeds and pests.

There are many issues that can cause soil compaction, including poor soil structure. Sometimes soils can become compacted due to an inherited problem and will need to be addressed a little differently.

How do lawn fungi spread?

Lawn fungi spread easily and quickly through a variety of means, including rain, wind, grass clippings, and even lawn mowers.

This is perhaps one of the main reasons why lawn care professionals avoid mowing fungus-infected grass without treating it, as the fungus can spread to neighboring lawns.

To prevent the spread of lawn fungus, many homeowners wait out the infestation in hopes of getting rid of it on their own. But not taking steps against lawn fungus, such as applying fungicides or improving nitrogen levels, can be detrimental to the health of the lawn in the short and long term.

Before you leave…

I have written a detailed article on the most common types of lawn fungus and their remedies, and the list includes fairy ring fungus, dollar fungus, powdery mildew, snow mold, and red thread.

Also, check out my article on the best lawn fungus treatment. I offer more details on how to get rid of fungus with herbicides or using natural methods.

Hi, I’m Alex Kuritz. As a child, I remember my family had one of the best gardens in the neighborhood. Very green and lush. As I grew up, I took care of and paid a lot of attention to not only my family’s garden, but also my neighbors’. I can say that I have years of experience and I’m here to share it with you.