Keeping your lawn healthy and lush involves a lot of work, including routine watering and fertilizing, mowing and adding herbicides for weeds. But if you are a South Florida homeowner, you also have to be on the lookout for fungal diseases which can damage your grass or sod. In fact, these diseases can ravage a lawn if not treated properly in a timely manner. Therefore it is important to learn the early warning signs of lawn fungus so you can catch these diseases early and protect your property.

Here are some of the possible warning signs of lawn fungus to look for:
Brown Patch: Brown patch fungus commonly occurs in South Florida heat and humidity. It affects certain species of grass worse than others–namely, Bahia, St. Augustine, and Bermuda grass. Brown patch begins as multiple small, circular areas of yellow-brown foliage that quickly expand and can engulf the entire lawn if not properly treated. Inside each circle, sprouts of grass will often recover from the disease, causing the circular patch to appear as a donut shape. Once the brown patch has begun to spread, you will need to apply a fungicide to eliminate the disease.
Rust: As the name implies, this fungus grows on grass blades and makes them appear yellow-orange, like rust. It begins as small dots but eventually can cover the entire blade. Once mature, the fungus will release reddish-brown spores that coat the lawn and also appear rust-like. As the infection spreads, you may notice your lawn thinning and the grass blades becoming torn and bent. Catch and treat this fungus as quickly as possible, because the tearing of the blades renders your lawn more vulnerable to other diseases as well.
Take-All Root Rot : If you notice patches of your lawn beginning to turn brown unevenly, ranging in diameter from a few inches to a few feet, take-all root rot may be affecting your turf. This fungal disease causes the roots to die, turning them white and making them weak. The grass is then unable to take up water or nutrients, and thus dies as well. Affected grass will be easy to pull up, since the roots are no longer functioning to anchor the turf. Keep an eye out for signs of this disease in spring and early summer, and keep your mow deck a little higher than normal, as this will help guard your lawn from infection. Applying fertilizer with higher rates of potassium can also help deter take-all root rot.
Preventing Lawn Fungus
Fungal disease is much easier to prevent than it is to treat. You can decrease the chances of your lawn becoming infected through a variety of best maintenance practices.
- Water your lawn early in the morning, never at night. This is because fungus spreads quickly so long as there is dew on the grass, especially when there is moisture present for longer than 10 hours–watering in the evening means your lawn will likely be wet for a long time, as opposed to watering in the morning when excess moisture will evaporate as the morning progresses.
- Avoid applying high rates of fast-release nitrogen to your lawn since the fungus targets rapid, lush grass growth. It is better to supply the nitrogen in lower rates over a longer period of time.
- Research the optimal mow height for your grass species, and keep the height of your mower deck within those parameters; shorter or longer growth than recommended renders your grass more susceptible to disease.