Cooler temperatures have arrived. The cooler weather makes it nice to get out in the yard and do some work.
The cooler temperatures also remind me that it is time to think about control of some of the disease problems that we have in our lawns. Large patch likes to show up this time of the year, but there is another disease problem that will show up in the spring. This disease is called take-all disease. Take-all is becoming a major problem in our lawns, especially on St. Augustine.
Take-all is caused by the fungus Gaeumannomyces graminis. This fungus is most active in the fall. The symptoms appear about the time of our first frost, so you don't see any sign until the grass doesn't green up in the spring.
This fungus likes to attack grass that is stressed and weak, so there are fewer problems on healthy, fast-growing grass. There are a number of factors that can cause stress on a turfgrass. One of the major stresses is drought. We have had plenty of this stress this summer. Low fertility levels and too high of a pH level can stress the grass and make it more susceptible to take-all patch.
Another factor is a shallow root system that is caused by light, frequent irrigation water. The top portion of the soil stays moist, which encourages disease problems.
Another factor that encourages take-all is thatch. Thatch is a layer of organic material made up of pieces of stems, shoots, roots and stolons of grass. These parts of the plant have more cellulose than the leaves and take longer to decompose. Thatch is a harbor for insects and fungi.
Because there are a number of causes of take-all disease, is there an easy cure for it? No. I wish we had a silver bullet to cure it, but it takes time and a management plan to overcome this disease problem.
The first step is to meet the nutrition needs of the grass. The best way to find out what your lawn needs is to have a soil test done. This will tell you the pH of your soil and what nutrients are available. Also, you will be given a recommendation for the analysis of fertilizer to use, when to use it, and how much.
When fertilizing St. Augustine, use a fertilizer that has two to three times more potassium than phosphorus. Potassium is the last number on a fertilizer bag. It helps increase drought resistance and disease resistance.
There are fertilizers on the market that have no nitrogen or phosphorus in them -- for example, 0-0-7. You can apply this now and the grass will take it in.
The next factor that the soil test will help you with is pH. Take-all patch likes a pH above 6.5. The higher the pH, the more likely you will get take-all. Therefore, the best pH for St. Augustine grass is between 5.5 and 6.0.
If you have been diagnosed with take-all and have a high pH, you can incorporate peat moss into the soil. Peat moss has a low pH and it will lower your soil's pH. Use 3.8 cubic feet of sphagnum peat moss per 1,000 square feet of area.
Next spring, you will need to aerate your lawn. This will loosen the soil and help the roots to grow deeper, and water and nutrients to infiltrate easier. You can top-dress the lawn with a good quality top-soil or compost mix to help breakdown the thatch layer.
If you had take-all patch this past year, treat your turfgrass with a fungicide now.
There are a couple of fungicides that you can use to treat take-all. The first is Myclobutanil. You can find this fungicide in products from Immunox and Green Light. The next fungicide is triadimefon. This is the chemical name of the fungicide Bayleton. You will need to re-treat your lawn in 21 to 28 days. Then in March, you will again re-treat the lawn.
This is a very hard disease to control. You will need to use the best management practices for growing a healthy St. Augustine lawn combined with a fungicide program to have the best results.
Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at email@example.com. The Extension Web address is www.ugaextension.com/columbia.
The Columbia County News-Times ©2013. All Rights Reserved.