Pensacola News Journal

for: Saturday, April 14, 2001

by: Daniel E. Mullins

Extension Horticultural Agent

Santa Rosa County

Lawn Problems Galore This Spring

I don’t envy the lawn care professional or homeowner whose goal is the “perfect” lawn - especially this spring. Overload comes to mind when considering the number of lawn “dead patch” calls and samples that we have dealt with during March and April.

The problems that we are seeing are mostly with centipede and St. Augustine grasses. That’=s the case, of course, because most of our area lawns are made up of these two grass species.

There is no single cause and remedy that applies to everyone’s lawn dead spots. So far, I have seen problems caused by Rhizoctonia brown patch, Pythium root rot and the dreaded Gaeumannomyces fungus, which causes centipede decline and take-all root rot in St. Augustine.

The difficulty in diagnosing lawn disorders lies in the fact that the symptoms are so similar. Regardless of the cause, the results are usually dead areas of various sizes and shapes.

Weather conditions over the past year or two have severely stressed many lawns and we are seeing the results, but that is not the only cause. Some of these problems we are bringing on ourselves with extreme maintenance practices.

Bear with me while I vent a few frustrations and list a few improper maintenance practices that are directly or indirectly leading to many of our lawn problems.

Low Mowing: Cutting grass too short weakens it by not allowing enough leaf surface area for sufficient photosynthesis to occur. Also, there is a direct relationship between cutting height and root depth. Short grass results in short roots and visa versa. Mow centipede at 12 to 2 inches and St. Augustine at 3 inches in sunny locations.

St. Augustine grass in shady locations would benefit from a 4 inch cutting height.

Daily Watering: Once established, I know of no case where daily lawn watering is recommended or required. Water deeply but infrequently, applying one-half surface inch per application. This amount will soak sandy soil 8 inches deep. If unsure of the amount that you are applying, place pans around the yard and calibrate the system.

Take control of the automatic system and water on an “as needed” basis, rather than on a schedule. Some wilting of spots within the lawn before watering will not harm the grass. Irrigate the next morning after these bluish-gray areas are seen. If you are watering an established lawn more than twice per week at this time of year, you need to calibrate the system and cut back on the frequency.

Fertilizer Overkill: Some fertilization is normally required in order to have a lawn of decent quality. On the other hand, I am seeing the results of problems due to excessive fertilization.

I have never seen a centipede lawn that starved to death, though I have seen many overly thatched, diseased and insect ridden lawns that were pushed too hard with fertilizer. The selection of fertilizer products and the amount applied needs some attention too. Watch future issues for a discussion about recommended fertilizers and application rates.

Question of the Week: Mole crickets tried to destroy my lawn last summer. This year I would like to be prepared for controlling them. What should I do?

Answer: Relax for now. It is the wrong time of year to apply control measures for mole crickets. Overwintering adults emerge during the spring, mate and disperse by flying. Eggs are deposited a few weeks later wherever the female chooses and the entire year’s population of young crickets are present by late June or early July.

Currently used products for mole cricket are therefore best used in early summer. The young crickets are at their most vulnerable stage at that time. Watch for a new biological control product that is scheduled to be available during the fall.