Beware of Late Fall Fungus in Warm Season Lawns

Beware of Late Fall Fungus in Warm Season Lawns

Late Fall Fungus

Beware of Late Fall Fungus in Warm Season Lawns

In the early spring, warm season grass begins to come out of winter dormancy and return to its vibrant green color. A common question and concern we receive during this time is, “Why are some parts of my lawn not greening up?”

There are many possible reasons for this problem such as inconsistent watering, insect damage, and pet urine, etc., but one often overlooked possibility is the damage caused by fungus that covertly took hold in the fall before your lawn even entered dormancy.

Late Fall Fungus

This is a photo of  large patch fungus in zoysiagrass taken on December 10th in Charleston, S.C. Left untreated, this fungus will not go away during winter dormancy. The fungus and the damage it causes will reappear in the spring and will continue to spread and cause further damage.

Fungus Can Take Hold in the Fall

It is true that fungus is more prevalent in the early summer months when southern lawns experience the combination of warm temperatures, consistently wet conditions, and high humidity. What a lot of homeowners overlook is that many of the same fungus-friendly conditions also exist in late fall, which can lead to the onset of fungus just as southern lawns begin to enter dormancy. The problem with this timing is that the damage can go unnoticed until the spring when the lawn greens up with visible circular patches of damage.

Late Fall Fungus Patch

This is a photo of fungus in centipede grass taken on April 12th in Charleston, S.C. The parts of the lawn damaged by fungus the previous fall have failed to green up. 

What to Do

If you see signs of fungus in the late fall–early winter, immediately apply a systemic fungicide. This should be done before your lawn enters dormancy. Also, cut back on watering and manage the buildup of fallen leaves on your lawn (read more). Next spring when your lawn begins to green up, reapply a systemic fungicide before you fertilize your lawn for the first time. Also, consider a more lawn-friendly and environment-friendly fertilizer program that delivers nutrients to your lawn in a manner that is less likely to cause fungus outbreaks.

Feed Your Lawn with Lawnifi

Generally speaking, most big box fertilization programs prescribe too much nitrogen, which can lead to fungus outbreaks. There are two problems with this strategy:

  1. Lawns need nitrogen—but not in copious amounts. Slow-release nitrogen fertilizers keep too much nitrogen from entering your soil and plants at once. They’ll also feed your lawn over an extended amount of time so that you don’t have to apply fertilizer repetitively.
  2. It is better to feed your lawn incrementally throughout the growing season (March—November); not just two times a year.

Sod Solutions recommends the Lawnifi Fertilization Program. Lawnifi gives your lawn what it needs in the form of nano-sized nutrients, exactly when it needs it in the form of easy-to-apply monthly applications from March to November. For these reasons, Lawnifi is less likely to cause fungus outbreaks.

It is important to note that even with the use of an improved fertilizer program, the timely applications of fungicide is still necessary for overall lawn health. If you fertilize your lawn with nitrogen before applying a fungicide and presently have a fungus, that fungus will expand exponentially, which can be disastrous for your lawn.

For more information on Lawnifi, check out this blog or visit To read more on general disease control, click here. Lastly, be sure to check out our Fall Lawn Maintenance Tips blog for more information in regards to other regular maintenance practices that should take place during the fall season

If your lawn is showing signs of fungus damage and has not gone completely dormant, it is not too late to apply a systematic fungicide. Be advised that you will also need to treat your lawn in the early spring when it begins to green up. Below are some suggested fungicides to consider.

  • Coverage: One bottle covers 2,500 sq. ft.
  • Active Ingredient(s): Propiconazole 1.45% and Lamda-cyhalothrin 0.08%.
  • Ease of Use: Hooks up to your garden hose for an even spray application.
  • Best Used On/For: Outdoor topical/contact fungus and general insect control.

  • Coverage: 10 lbs. covers between 2,500–5,000 sq. ft.
  • Active Ingredient(s): Azoxystrobin 0.31%.
  • Ease of Use: Requires a drop or broadcast spreader for application.
  • Best Used On/For: Systemic strobilurin fungicide used to control certain turfgrass diseases.

  • Coverage: One gallon covers between 36,000–128,000 sq. ft.
  • Active Ingredient(s): Azoxystrobin 8.8%.
  • Ease of Use: Requires tank mixing and spray application.
  • Best Used On/For: Tough turfgrass diseases in lawns, landscapes, sports fields and golf courses.

  • Coverage: 2 lbs. covers between 21,000–53,000 sq. ft.
  • Active Ingredient(s): Trifloxystrobin 8.33%, Tradimefon 41.67%
  • Ease of Use: Requires tank mixing and spray application.
  • Best Used On/For: Preventative disease control.

  • Coverage: One gallon covers between 12,800–25,600 sq. ft.
  • Active Ingredient(s): Mono- and di-potassium salts of phosphorus acid 45.8%.
  • Ease of Use: Requires tank mixing for spray application.
  • Best Used On/For: Turfgrass disease.

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Want to learn more about achieving a great lawn? Check out our other Sod University tips here.

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