Spotting and Treating Summer Lawn Fungal Diseases

Rising temperatures, combined with humidity create the perfect conditions for summer lawn fungal diseases to emerge. While some are cosmetically unappealing, but harmless, other summer lawn fungal diseases are more serious and require treatment. Spotting and treating summer lawn fungal diseases often requires a professional’s eye and guidance for proper treatment. Here is a primer on spotting and treating summer lawn fungal diseases.

Harmless, but Unsightly Lawn Fungal Diseases

All three of these will not kill the turf. Fungicides should only be used in severe cases. A good shot of fertilizer will help to grow out the disease.

Severe Lawn Fungal Diseases

Pythium Blight

Pythium blight tends to hit perennial ryegrass the hardest. It first appears as small, sunken, circular patches. Affected leaves will be matted down and look orange or dark gray, and greasy. This disease pops up when there is excess moisture on the grass and night temperatures exceed 65 degrees. Excess fertilization will also favor the growth of Pythium Blight. This disease must be treated with a fungicide immediately, and watering needs to be adjusted or shut off until it’s under control. Affected turf will have to grow the disease out, and if caught early, could recover. If caught too late, then the lawn will need to be re-seeded.

Brown Patch

Brown patch tends to affect fescue the hardest. It appears with small, round, bleached to straw colored spots. It’s important to avoid excess fertilization after Memorial Day, because nitrogen contributes to the spread of the fungus and can actually kill a lawn with active Brown Patch disease . Fungicides should be applied immediately, and watering adjusted or shut off.

Leaf Spot

 Leaf spot tends to affect bluegrass the hardest. Small, round lesions will appear on the leaf surface. If not treated early enough with fungicide, the grass blades will go through a process called “melting out”, and the roots and crown of the grass will rot and die. Leaf spot can be prevented by ensuring you don’t mow the lawn too short. It’s also important to keep mower blades sharp, as dull blades can tear the leaf tip and leave it susceptible to infection. Like patch disease, applying nitrogen to an active leaf spot outbreak will kill the turf, as the fungus will attack any lush, new growth.

Is it Fungus or Insects?

To the untrained eye, whether you are facing a fungal disease or an insect issue can be difficult discern. One way to distinguish is to identify whether the damage is spotty or contiguous. Fungus tends to “hop” from spot to spot, while insect damage is generally contiguous. Also, in the morning, you might notice some white, wispy, spider-web looking material on the grass during the morning. This is mycelium, and it’s how fungus moves around. It will burn off in the late morning and won’t be visible past then. Infected turf leaves will have small lesions on the blades at the outer edge of the infected area. And of course, the best way to tell if whether you have an insect issue is if you spot the critters on your turf.

How to Prevent Fungal Diseases

The best way to fight fungal outbreaks is to minimize the conditions that favor them.

Watering: Do not water your lawn before 4am or past 5pm during summer. The reason behind this practice is that it is important to let lawns dry out before night. This encourages good air flow, which is critical to reducing fungal outbreaks. For established lawns, our experts recommend 1” of water per week, either in one session or split between a ½” session twice a week.

Mowing: Lawns that are shorter than 3 ½” are more at risk of developing fungal disease. During summer, especially the hotter months, our team recommends mowing between 3 ½” and 4”.

Pro Tip! American Landscape Lawn Maintenance clients can request our new moisture manager, which is a great option to keep turf hydrated while reducing the amount of water needed. The moisture manager binds water into the root zone, keeping the leaf surface drier for longer.

Our lawn care experts also recommend keeping mower blades sharp to avoid unnecessary turf injury. If your lawn has an active fungal disease, you may need to disinfect mower wheels and blades to avoid spreading fungal spores throughout your lawn.

Fungal Disease Treatment

If, despite your best efforts, your lawn falls victim to a fungal disease, we recommend the use of fungicides. It’s important to remember that these products do not cure turf disease, they simply arrest its development. Fungicides buy you time. Infected turf should be sprayed and given time to grow the disease out. And of course, different diseases require different fungicides to treat.  We highly recommend engaging professional lawn care experts to treat your lawn.

American Landscape’s lawn care professionals have years of experience in spotting and treating lawn fungal diseases. Get in touch today to learn about our maintenance program options or for a consultation on your lawn care needs. (262)252-4260