Diseases affecting lawns

Every fall I get calls from about dying lawns, and most of them are fungus-related. This year, I've already visited with a number of folks who own TX land and are having fungal problems with their lawns during the spring.

"Recent mild weather has our fungi problem showing up ahead of schedule."

Fungal problems always start in this season. Cool, moist weather tends to get fungal spores off to a good start. They stall during the typically hot, dry summers that we as lovers of country living have gotten used to, and then finally culminate in a crescendo of headaches in the fall, with its weather so similar to spring. However, the recent bout of mild weather has these problems showing up ahead of schedule.

Trying to understand all the factors that can lead to disease can be complex. Some include the following:

  • Excessive thatch
  • Low soil fertility
  • Too much nitrogen
  • Improper soil moisture
  • Compacted soils
  • Heavy, prolonged dews
  • Uncontrolled infection from previous years
  • Weather patterns

Turf areas that remain wet are prone to disease. When you think of where mold will grow in your house, we all agree areas that stay moist are at the most risk.  Following the same concept, let your lawn dry out between waterings. To reduce the time your lawn stays wet during any 24-hour period, only water when it's already damp from the dew. Afternoon or early evening watering prolongs the time during which moisture-loving fungus can develop - and who wants that?

Diseases affecting lawnsBeware of fungus that can sprout in your lawns.

Improve drainage if necessary and fill in any depressions in the soil. Above all else, avoid over-watering. It's better to water infrequently but deeply - 6 to 8 inches deep. 

Have your soil tested, and fertilize the grass based on what that test recommends, taking care not to use too much nitrogen fertilizer. If possible, adjust the soil pH in the root zone to be slightly acidic, preferably between 6.0 and 6.8. Do not apply more than 4 pounds of nitrogen fertilizer per 1,000 square feet per year for St. Augustine grass, or 5 pounds per 1,000 square feet per year for Bermuda grass.

If thatch build-up is a problem, use a vertical mower to break it up, aerate the soil with a core aerifier and mow at the proper height: 2 to 3 inches for St. Augustine grass and 1 to 1.5 inches for Bermuda grass.

Soil also should be aerified if it is compacted. Compaction keeps water and air from moving into the soil and reduces plant shoot and root development. Aerification of compacted soils once or twice a year helps break up packed layers, to allow air and water to reach root systems.

If diseases are currently affecting your lawn and have the potential to adversely affect your farmhouse plans, you'll probably need to apply a fungicide. This should be applied along with a high volume of water - or water thoroughly right after application - to ensure the product moves into the grass's roots rather than drying on the leaves.

Common hose-end applicators work well for soaking fungicide into the root zone. Fungicides are most effective as preventative treatments - much less so after the disease is well established. However, it is usually effective to treat diseased areas in the spring, after the easily removed infected stolons are raked out or lifted away. Two applications may be necessary: If so, do one between 3 and 4 weeks after the other.

Finally, remember that in your quest to have a lush, perfect lawn, even the golf course professionals who have degrees in turf-grass management still have problems to contend with!  

For more information, contact the Angelina Extension Office at 936.634.6414 or email cw-sims@tamu.edu.

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