5 Most Common Things That Are Killing Your Grass

1. Mowing too close – Quite often we are called out to take a look at someone’s lawn to diagnose why their grass is dying. And very often the first thing I notice is that the grass will be mowed very, very close. Depending on the type of grass, this could be the culprit for the grass thinning out.

Don't scalp your lawn

Scalping your lawn causes dead grass

If you have a cool season grass like Fescue, Bluegrass, or Ryegrass, these generally need to be cut higher than warm season grasses. I recommend cutting these no lower than 3″, they just look better when mowed taller, and will usually hang in through the Summer months a little better if cut at that height.

Many times people will say something like, “I cut it way down there low, so I don’t have to mow as often”. Mission accomplished!! Mowing cool season grasses that low will stunt them or plain old kill them. Do your cool season grass lawn a favor and cut it up higher, I promise it will look better, and survive longer!

Bermuda grass, Zoysia grass and other warm season grasses can be cut much lower and they will thrive. It’s actually better for this type of grass to be mowed 2″ or lower. Golf courses, football fields, baseball fields and soccer fields are routinely seeded, sodded or sprigged with warm season grasses like Zoysia or Bermuda. They are usually cut 2″ or lower, sometimes as low as 3/8″ on golf courses. Some golf greens are Bermuda, they are cut lower than 3/8″.

So, if you don’t know what type of grass you have, find out, then start mowing it at the recommended height for that type of grass in your area of the US.

2. Moisture Stress – Fescue lawns in the South need water. They will tell you when they are thirsty if you know what to look for. The grass will start turning a lighter shade of green, and then the blades will start wilting, shriveling up and the grass canopy starts to get thinner and thinner until the majority of the grass plants go dormant.

Wilting Fescue Grass Lawn

Fescue Grass beginning to show signs of moisture stress

Most cool season grasses are going to require more water/rainfall than warm season grasses like Bermuda, Zoysia, Centipede and other similar grasses. The nature of warm season grasses is that they grow best in warm or hot climates and temperatures, so part of their biology is that they will grow better and survive better with less watering or rainfall.

If you start to see your own lawn looking like the one in this picture, it’s time to water!

3. Too Much Shade – The warm season grasses we have mentioned already grow best in full sun conditions. Usually, Bermuda or Zoysia and their other cousins will grow up to the shade line, or drip line of a tree and slowly thin out. The grass will essentially show you where it’s limit is on how much sun it needs. So, if you have a Bermuda lawn it’s not going to grow under the trees. As a tree matures that you have planted in the lawn, the bare spot under it is going to be in proportion to the size of the tree.

Too much shade

Areas like this are difficult to grow grass in. These parts of the lawn are best left to landscape beds

Fescue, ryegrass, bluegrass and creeping red fescue will grow in the shade but will suffer from the next problem that arises with grass growing in deep shade. It’s not just the shade, but competition with the trees for water, too many leaves falling on the grass and choking it out and lack of lime and other nutrients that are robbed from the soil by the trees.

Growing grass in the heavy shaded areas of any lawn is usually very difficult, no matter what the type of grass. Many times it’s best to just give up the idea of having grass in these areas and turn them into landscape beds, gravel areas or another option.

4. Fungus or Insects – Lawns that are dying off with no obvious signs to the untrained eye are often dying from a Fungus or insect problem. These problems will usually start killing off grass and before we are called to investigate, the grass has large dead spots all over, which are usually not going to recover without reseeding.

Brown Patch Fungus on Fescue Grass

Brown patch fungus on Fescue grass

For Fescue grasses in the South, one of the biggest problems we have with Fungus is Brown Patch. It will start in a small circle as small as a quarter, and slowly start increasing in size until it has killed out circles of grass 2 to 3 feet in diameter. Then, the homeowner sees the problem and calls us. Fungus can be controlled with applications of fungicide, either as a preventative application before it ever shows up, or as a curative application after it does show up. However, our experience has been that once it gets started and kills off sections of a cool season lawn, that section doesn’t recover during that year and has to be over seeded in the fall.

Insects will start chewing on either the grass stems or roots of grass plants and cause the same type of slow killing off of the grass plants as the Fungus does. Only insect damage is usually not in a circular pattern. It will just be a large section of grass that looks thinner, weak or just overall not as healthy as the rest of the lawn. Army worms are a common problem we have in the South, they will attack both warm season grass and cool season grasses. You might go for several years without having a single army worm in your lawn, then have them invade by the thousands for a few years in a row.

Brown Patch Fungus on Fescue Grass

Brown patch fungus on Fescue grass

army worm damage in a bermuda lawn

Army worm damage in a bermuda lawn

Army Worms in lawn

Army worms invading lawn

Army worms are fairly easy to eliminate, an application of insecticide will do it, sometimes two applications are needed. But the biggest issue is to get the insecticide applied as soon as you see any army worms on the lawn. Waiting even a day or two can give them enough time to do major damage. The picture shown is what army worms look like.

Grub worms are the larva of a common “June Bug” as most people call them. Asian beetles are another common name. They grow in the ground and will eat  the roots of plants, but that’s not the only damage caused by them. Moles will start running through the lawn looking for them and do major damage to the lawn by tearing up the turf, cutting ruts in the lawn and killing lots of grass.

 

An insecticide application will also control them but needs to be done at two times of the year when the grubs are at the closest to the surface of the lawn. The insecticide does a much better job of killing them at this point.

Another good idea is to do some mole control at the same time that you do the insect application. Moles will do so much damage to a lawn at times that it looks like someone has taken a roto-tiller to the lawn.

5. Improper Applications of Fertilizer/Insecticide/Herbicides – We will get called several times a year to diagnose another problem, we call it killing the lawn with kindness. Or in other words, the homeowner has decided to make applications of fertilizer, insecticides or herbicides to the lawn, but didn’t read the directions.

lawn damaged by too much fertilizer

Fertilizer damage to a lawn

All bags or bottles of any pesticide will have the directions for proper use and application rates on the label. Please read the label first before applying any product to your lawn. At the least, you could damage your own lawn. At worst, you could kill grass in your neighbor’s lawn, the ditch in front of your house, or worse yet would be if you have a pond or other waterway on the downhill side of your lawn. You could kill fish or even pets with an improper pesticide application.

You will also need to know the size of your lawn or property either in square feet or acres, and know how to determine that number. Without this number it is impossible to make a proper application of any pesticide. If you don’t have the proper equipment to apply the pesticide with, you are best off to call a professional to do this for you. It could be cheaper and easier for you and your health.