Question
Hi,

I live in Zone 9a...and have st augustine(fortam)lawn.We water the lawn twice a week And fertilized it last in feb with ironite.However now with rising temperatutes the grass that was growing nice and green  in some spots have suddenly dried ,pale thin grass although there are few sprigs of alive grasses between them .Can you tell what the problem is...Does it require fertilizing now and if so which would be the ideal one for this lawn.

Answer
I suspect that your lawn has either been exposed to a leathal lawn disease or been attacked by chinch bugs

If the damage occurs primarily in circles and spreading slowly then it is likely lawn disease.

If the damage occurs randomly in larger areas (especially in more sunny areas) and quickly, then it is likely insects. If this is the case, I recommend spaying for insects.

Fertilizing a lawn which is stressed by disease or insects can make the situation much worse. Fertilizing would not be a good cause of action right now.

When lawns are nutrient starved the grass tends to turn light green and stop growing. Fertilizing will turn the leaves dark green and the lawn will grow more rapidly requiring more mowing. A lawn needs to be fertilized every 2-3 months to stay healthy. Dead, brown grass is not lack of nutrients but disease, draught, or insects.

Unfortunately, ironite is not a lawn fertilizer. Ironite is an iron supplement which only works if the lawn is iron starved (which most lawns are not as soil typically contain adequate levels of iron). You should instead fertilize your lawn every 45-60 days with a LAWN FERTILIZER. Use about 3 lbs of lawn fertilizer for each 1000 sq feet of lawn area.

When you water, it is preferred to water deeply and (relatively) infrequently. Instead of watering daily for 10 minutes, it is preferred to water 1-2 times per week for 1 hour each time. A deep through soaking is better than shallow frequent applications. If you do not water atleast for 60 minutes, then you are not watering deeply enough.

A lawn which is fertilized regularily, mowed frequently, and watered properly will usually be able to handle a certain amount of stress from insects and disease. A stressed lawn (from not being fertilized properly or from lack of water) will be more susceptible to disease and insect attacks.

Once you have indentified the cause and corrected same, you may have to re-plug the lawn (depending on how extensive the damage is). Then you need to introduce a regular watering, fertilizing and mowing practice which supports the lawn.

Note:
St. augustine can turn brown if you have had a sudden cold spell. This can happen if temperatures fall below 60F consistently for 10-15 days or if night temperatures go into the 40F or lower. If this is what has happended in your area, then you can just wait until warmer temperatures return and the grass to start growing again. Then mow off the dead grass and start to fertilize and water.

However, if the temperatures are warm and the lawn grew through winter, and only now (in early stages of active growth) show sign of damage, it is almost always due to insect damage which are most active at this time.

If in doubt, have a pest control expert, landscaper, or lawn care company review the lawn and check for insects, especially chinch bugs.

Sorry to hear about your lawn. I will keep my fingers crossed.

-- Kenneth