Causes

• When properly cared for in the right soil, St. Augustine grass can fight many lawn problems on its own. When poor maintenance or uneven weather patterns create an unstable environment for the lawn grass, the grass can become weak and vulnerable to damaging invaders.
  
  

Diseases

• Fungal, bacterial and viral diseases can attack a St. Augustine grass lawn, causing dead grass and unattractive spots. St. Augustine grass is particularly vulnerable to fungal infection. The most deadly fungal problem on St. Augustine grass is take-all root rot, which creates a spreading area of diffuse discoloration and dead grass. St. Augustine grass is also at risk of other fungal diseases like brown patch grass disease and gray leaf spot disease.
  
  

Weeds

• When St. Augustine grass is raised for its luxurious carpet, weeds can put an unsightly mark on an otherwise pristine lawn. Lawn weeds include two basic types: grass weeds and broadleaf weeds. Common grass weeds that invade St. Augustine grass include Bermuda grass, crabgrass and annual bluegrasses. Broadleaf weeds are plants like dandelion and clover, which have wide leaves.
  
  

Insects

• Insects on a St. Augustine lawn can look similar to fungal problems. Because this type of grass tends to accumulate thatch--a thick layer of dead grass and other organic material that builds up around the bottom of the grass carpet--it is at higher risk of insect problems than other types of turfgrass. Chinch bugs are the most common insect invader seen in turfgrass; they are about 1/5 inch long and dark in color with white wings. Chinchbug saliva is toxic to plants, so these bugs cause more damage than most other unwelcome lawn insects.
  
  

Prevention/Solution

• Preventing and treating St. Augustine problems starts with strengthening the lawn grass through proper care and maintenance. Mow this grass to a height of 1 to 3 inches weekly or whenever the lawn has grown 1 to 1 1/2 inches. Mow no more than one-third the height of the existing grass at a time. Water the grass in the morning to avoid leaving a wet lawn in the evening. When thatch becomes a problem, lawn aeration can help break apart the material buildup.