Can a Lawn Mower Spread Fungus?

Approx Reading Time: 8 minutes

Fungus can be the bane of your life if you have a lawn.

If you mow different lawns, one of the concerns you will eventually have is about the risks of spreading the fungus. And with how damaging fungus can be to a lawn, potentially completely destroying it, your concerns may be well justified.

To reduce the risks of contamination, we need to find out what can spread the fungus infection. And one of the first things that will pop into anyone’s mind is – your lawn mower.

So, can a lawn mower spread fungus? Yes, lawn mowers can spread fungus. Fungus can attach to the deck, cutting blade(s), and the wheels and quickly spread out and contaminated different parts of the lawn. To reduce the chances of your lawn mower spreading fungus, make sure to clean it properly, and maintain a healthy lawn environment.

However, there are a few more things that are important to understand. Just because you are using a lawn mower doesn’t mean you will 100% introduce fungus to your lawn.

Below I explore all the different caveats and details about lawn mowers and fungal contamination.

How Does Lawn Fungus Spread?

One of the ways to make sure we keep our lawn in the best condition and health possible is by understanding how fungus acts.

There are three basic necessities or conditions that need to be met for the fungus to spread effectively. All three need to be met. Otherwise, fungal contamination is unlikely.

  1. A host – The fungus needs a host which it can attach to. In other words, this is the grass, weeds, leaves, etc.;
  2. Means of spreading – These are the fungal spores, which need to get in contact with the host plant;
  3. A proper environment – The right environment in which the fungus can grow and spread;

Now, consider for a moment what we are facing here. The first two – plants and the spores – are a fact of nature.

The plants will be there all the time, and fungal spores are often found in the soil itself. You cannot avoid them nor eliminate either of them.

The last element – the environment – is something that we can actually control. And this is the key here. But what about your lawn mower?

How a Lawn Mower Can Spread Fungus

There are numerous ways fungus spores can spread to new locations.

The microscopic fungal spores can easily attach themselves to the undercarriage of your lawn mower, the blades, the wheels, and even to your boots and clothes.

From there, it doesn’t take much effort for the fungal spores to contaminate other lawns that you mow with the same lawn mower (even just walking over the grass can contaminate it in some cases).

Things don’t stop here.

Before blaming your boots or your lawn mower, let me tell you that fungal spores can also be airborne, meaning they can spread through the air or wind.

This last point really goes to show how important it is to maintain a healthy environment that does not allow the fungus to grow and thrive.

This can be the difference between one lawn having no sign of any fungus even though the neighboring lawn has brown patches.

As a matter of fact, lawn mowers can even spread weeds as well – I wrote an article on this very topic recently, you can check it out here. And this is why we need to be very thorough with the cleaning of our mowers.

What Are the Most Common Fungi That Can Be Spread by a Lawn Mower?

There are a lot of different kinds of fungi that a lawn mower can spread.

  • Brown Patch
  • Pythium
  • Leaf Spot
  • Dollar Spot;

The different types of grass are susceptible to different kinds of fungal diseases, so which one you have can also depend on the type of your lawn.

How to Tell if Your Lawn Has Been Infected by Fungus

There are a few sure-fire ways to find out if your lawn mower is spreading fungus.

The most common signs of fungal disease are:

  • Discolored patches of grass;
  • Brown, yellow, or white rings that increase in size;
  • Orange, black or grey spots found on the blades of grass;
  • Slimy looking areas of the grass;
  • Small web-like parts on the grass; and
  • Orange, yellow, or rust-like powder on the grass.

How Exactly Can Mowing Spread Fungus?

Even if you have the cleanest, most sanitized and disinfected lawn mower in the world, the fact is, you can still introduce fungus to your lawn just by mowing it.

This can happen in a few ways. But usually, it is connected with weakening the grass.

When you are mowing the grass, you are cutting parts of it. This creates stress. If you cut large pieces of the grass in one go, this will weaken it and make it more susceptible to fungal disease.

This is why people often recommend cutting no more than one-third of the length of the grass at a time, then waiting a few days before cutting it again.

Another way mowing can be highly stressful to the grass is if you are using dull blades or mowing the grass while it is still wet – I even have an article about the possible dangers of mowing wet grass, you can check it out here.

This can result in rough cuts that are not clean, pulling the grass out of the soil and damaging it enough so that fungus can take over.

Do You Have to Sanitize Your Lawn Mower?

Of course, one of the ways to keep fungus from spreading to your lawn is by sanitizing your lawn mower. If things are definitely getting out of control, this may be a necessary action you need to take each time you are going to mow a different lawn.

However, let me point your focus back to the three main conditions fungus needs to spread.

Maintaining a healthy environment is vital in order to maintain a fungus-free lawn. In which case, your lawn mower may not necessarily need to be sanitized or disinfected.

How to Lower the Chances of Your Lawn Mower Spreading Fungus

There are a few things you can do that can greatly reduce the chance of fungal infection. These are:

Taking Care of the Environment

It is always better to treat a problem at its roots.

This is why the best course of action here is to start by making sure you are taking good care of your lawn at all times.

Sometimes unfavorable weather conditions can throw a spanner in the works, but we need to be mindful and prepared for that.

To make the lawn less susceptible to fungal disease, we need to ensure proper watering and fertilizing, and also, the mowing process needs to be timed right.

  1. Water the grass in the morning. Avoid doing it at noon or late in the evening;
  2. Make sure to use fertilizer which is approved for your type of grass; and
  3. Don’t cut too much of the grass in one go.

A great many people use their lawn mowers for mulching as well. Much can also be a good place for the fungus to grow. The main reason it happens is because of mulching wet grass.

Some fungal pathogens actually prefer living in the mulch. The good thing is that mulch fungus, although not very pretty to look at, is usually not dangerous.

Properly Cleaning Your Lawn Mower

Cleaning your lawn mower is vital for the future prevention of disease.

It is best to clean the undercarriage after mowing; otherwise, the clippings can dry and form a crust that may be challenging to remove.

Some mowers have washout ports, which make the whole cleaning process a breeze. Alternatively, you can do the following:

  • Empty the fuel tank or run it empty;
  • Disconnect the spark plug;
  • Tilt the lawn mower on its side;
  • Use a garden hose to spray the undercarriage and scrub off the gunk and the grass clippings using a file or scraper; and
  • Scrape off and rinse any grass clippings and dirt from the top of the mower too.

Make sure to keep the part of the mower where the carburetor and the fuel tank are up, in order to avoid any fuel spillage if you are going to try and clean it while the tank is full. Although not recommended, it can be done.

Before cleaning your lawn mower, make sure to follow the cleaning recommendations in your user’s guide that came with the mower. Some mowers may have model-specific cleaning instructions that need to be followed.

Using Fungicide Products

Fungicides can be a valuable ally in the fight with fungal disease.

It can take some time for the grass to fully recover.

Some may recommend not to treat the lawn, but this is not a good idea because the brown spots and patches will remain like that. In most cases, the chances are the fungus will not go away on its own.

Bagging the Clippings

Last but not least, while you are mowing your grass, make sure always to bag all the grass clippings.

You want to remove the contaminated clippings from the grass as much as possible and not use them as mulch or anything like that.

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!