Ask Burton: This week, we’re talking the lawn again – and how to head off a problem before it becomes serious. Q: I have a St. Augustine lawn and I’m starting to see irregular brown spots in it; the runners are still mostly green, but the leaves of the grass are rotting off right at the base, against the runner. This happens almost every fall, and I’d like this problem to go away. What is this, and how do I stop it?

A: This sounds like brown patch, a common turf disease in the fall in North Texas. It can affect other grasses as well, but is most common on St. Augustine. Here’s our best recommendations for treating it now, and preventing a repeat next fall.

  • Apply a labelled fungicide. Ferti-lome Systemic Fungicide spray or Bonide Infuse granular fungicides are both effective. They’ll help with the current problem, but are particularly good at stopping the disease from showing up in the first place. If you’re dealing with this problem every year, preventative fungicide application should help.
  • Don’t over fertilize! St. Augustine is not as hungry a turfgrass as Bermuda; excessive amounts of high-nitrogen fertilizer encourage fungal disease. If you’re having problems regularly with this disease, consider cutting back one fertilization a year, and send off a soil sample to the Extension Service for an accurate view of what your soil needs before the next time you’d fertilize. You might be surprised, and see you should fertilize less, or skip a feeding entirely.
  • Mow frequently, and not so tall. Thick layers of thatch encourage both chinch bugs and fungal disease in St. Augustine. If you normally maintain your lawn taller than you should, this happens more often. Rent a powered aerator to help poke holes in heavily thatched lawns in April.
    Water early in the morning, only, and less frequently. St. Augustine likes water, but apply it less frequently – just water harder the days you do water. This encourages deeper rooting, and letting your lawn dry better between watering times will reduce the chance of fungal disease.

 Burton specializes in diagnosing and solving plant problems. If you have a question for Burton, please email him at and include photos showing the problem.