Dangers of too much nitrogen
Nitrogen is important in feeding a healthy lawn, but be careful not to overfeed it! Too much will cause excess growth, resulting in overly succulent leaves and shoots. This can lead to your lawn attracting insects, mites, and other pests. This may also lead to the development of a very thick thatch layer and even fungal diseases. An out-of-control lawn is difficult to restore, so it’s better to prevent it altogether by getting the nitrogen right.
How much nitrogen is the right amount?
On Bermuda grass, it’s important to use around seven pounds per thousand square feet yearly. Overall, Bermuda can take a lot more nitrogen than Zoysia.
As For Zoysia, the sweet spot is only about two pounds per thousand square feet yearly. Zoysia doesn’t ever need more than your typical starter fertilizer. It’s important to not overdo your nitrogen if you have a Zoysia lawn.
Zoysia grass grows a lot slower than Bermuda, so it consumes far less nitrogen.
Zoysia and Bermuda may look similar, but you really can’t treat them the same at all. Importantly, make sure to split your yearly nitrogen across several applications, not all at once.
Types of fungi that affect Zoysia and Bermuda
Brown Patch
The fungus develops in mild, humid conditions – usually in the spring or fall. Brown Patch typically appears first as a darkened green circle but eventually turns brown as the grass dies out. The size of the circles can range anywhere between a few inches to multiple feet in diameter.
Dollar Spot
Dollar spot most often infects grass experiencing excessive stress, and taking advantage of its weakened defenses. The disease manifests as tiny tan or straw-colored dots in the lawn, discoloring about quarter or silver-dollar-sized areas. From time to time you may notice cottonlike strings of fungus webbing in your grass as well. The fungus will grow and cause severe damage to your lawn if left untreated.
Rust
Rust fungus‘ ideal growth conditions are between 68-86 degrees (F), and wet. If the leaves have been soaked for 6-8 hours through the night, followed by rapid heating, you’ve got the perfect breeding ground for Rust. The fungus appears as tiny yellow powdery dots on the blades, slowly growing and eventually rupturing to release spores. The good news is, that rust doesn’t typically flat-out kill your grass, but it does harm and leave it weaker.
Powdery Mildew
Powdery Mildew can spread across lawns with bad air circulation, high humidity, low light, and moderate temperatures. The fungal infection looks similar to a frost layer, but is actually mycelium. Grass affected by this fungus will turn yellow and wither over time.
Fairy Rings
Forming to break down decaying matter in the soil, fairy rings aren’t necessarily a result of high nitrogen, and are typically just cosmetic blemishes that go away, but are worth mentioning here. They look like brown or dark green rings, sometimes sprouting mushrooms in the discolored region after rainfall. Seeing Fairy rings in your lawn doesn’t mean you’ve overfed your lawn, but may indicate something worth paying attention to in the soil.
Pythium Blight
Pythium Blight spreads very fast, usually along drainage lines. Appears as small circular patches of collapsed wet leaves. At morning time, you might notice cottony white mycelium. If left untreated, Pythium blight will quickly overtake your lawn, and can permanently kill it.
How to treat a fungal infestation on a Zoysia lawn
Really, the most important way to stop a fungal infestation is prevention, because by the time signs of infection show up, the damage is often already done. This doesn’t mean you should do nothing – catching it early with fungicide can save the roots, and allow your grass to regrow without being replaced. According to okstate.edu, the best routine to follow is to:
- Manage Your Drainage – keep water from pooling on your grass, and water between 5-9 AM
- Mowing Regularly – if your lawn is already infected, never mow while the lawn is wet. Some fungi spreads through water, so be sure not to send it flying everywhere. Try to maintain a height of 1 – 1 1/2 inches.
- Fertilization – no more nitrogen than 3 lbs / 1k sqft / yr, and do so in three separate but equal applications spread out through the year, though we recommend no more than 2 for the DFW area.
- Dethatching – do not dethatch while a fungal disease is active, wait for the disease to become inactive and the thatch to warm up.
- Fungicide Application – target areas with a history of fungal infection, which are most likely to have a reoccurrence.