Karen Cambre, Sharpe, Kenneth W.
News article for October 9, 2017
There are a number of lawn problems that occur during the fall of the year that can make for a dismal looking lawn in the spring. Many of these problems go unnoticed by the homeowner until spring when the grass is very thin.
I have had some reports of tropical sod worms over the past few weeks. I have even seen some damage in my own lawn. This damage shows up as large brown areas in the grass and many people just think it was the dry weather that we had in September and never pay much attention to it. If you look at the grass blades, they will either be completely missing or will have lots of missing foliage from caterpillars feeding.
Sod webworms feed at night and will not be present up on the grass blades when you check them in the daylight hours. If you see where grass blades have obviously been chewed and you do not have livestock, then you should be thinking about treating for worm damage.
I have had problems finding the worms myself in some situations, but they are usually down under the thatch layer during the day. While looking you might see dark green colored pellets at the base of the grass plants, this would be castings or excreted grass after the worm finishes digesting and would be another positive identification.
Another indicator that you have sod webworms is the when you look at your lawn in the morning while the dew is still present, you will see extensive webs left in the grass as the water droplets attach to the webs. This is where they get the name sod “web” worms.
When I cut my grass this past week and first noticed sod webworm damage at my house, I saw a lot of moth activity coming out of the grass and from under trees. If you turn on the outside lights right after dark you can attract a lot of sod webworm moths if they are present in the area. Sod webworm moths are going to be relatively small, only ½ to ¾ inches long and have a wing span of about 1½ inches wide. They are tan to gray in color and have a snout like projection on their foreheads.
I would use an insecticide with bifenthrin or Sevin to spray the lawn. If you have a yard that is too big to spray, then treat the spots infested and expand out 3 to 4 feet past where you see browning. Continue to monitor your yard as moths are constantly laying eggs when active and you can have a new hatch ready to eat in 7 days.
In my yard and others I have seen, sod webworms seem to have a preference for carpet grass, followed by St. Augustine grass. They will also eat centipede and Bermuda but usually not first.
Chinch bugs have also been reported. This is another dry weather problem that many mistake as browning due to lack of water. In this case you will not see missing foliage but grass blades shriveling up and browning. This is caused by chinch bugs sucking the base of grass plants. Chinch bugs are small and not readily visible in the lawn. They are only an 1/8 inch long, have a black body with white wings that form a distinct white triangle on their back.
Try using a lemon scented soap mixed in water and pour it on the brown area. Wait about 5 minutes and usually you will run chinch bugs or sod webworms up onto the grass blades so you can see them. I do not find this to be 100% effective, many times I end up down on my knees looking in the thatch. Another clue is that chinch bugs will not eat in circular patterns. The brown spots will have very jagged edges and will typically turn yellow or orange before turning brown. The same treatments that are used for sod webworms will control chinch bugs.