The summer months in Florida can be some of the most challenging for keeping our lawns looking good. We normally have heavy thunderstorms that produce short bursts of heavy rain that can wash nutrients from the soil. For this same reason, you should be very careful with fertilizers and pesticides that can wash out of our lawns and into storm drains. Many people believe that you should put out fertilizer or pesticides when rain is predicted so that it is watered in, when in reality our heavy rains will wash these away. The best management practice is to put down fertilizer and any granular pesticides before your scheduled irrigation day. This way the gentile sprinkling will dissolve the chemicals directly into the soil. Research shows that too much fertilizer during summer months actually can increase chinch bug infestation on St. Augustine grass. Try spraying Iron sulphate instead to green up the lawn but not create lush growth that is tasty to pests.
Areas of the lawn that are turning straw colored and dying can indicate an insect infestation. Chinch bugs infest primarily St. Augustine grass. Grubs eat the roots of several of our grass
varieties, as do the caterpillars of the sod web worm moth. For more complete information on lawn pests see the University of Florida/IFAS publications at http://edis.ifas.ufl.edu/topic_turf_pest_insects
Weeds can also seem rampant during the heat of summer. Be cautious with herbicides during this time. When the temperatures are 85 degrees or higher, weed control chemicals can damage the grass along with the weeds. This goes for weed and feed fertilizers also. Keeping your grass healthy will help crowd out weeds. Mowing the grass at the proper height can also help deprive weed seeds the light they need to germinate and grow. St. Augustine and Bahia grass should be mowed at 3 1/2 to 4 inches. Dwarf St. Augustine and Bermuda can be mowed much shorter at 1 to 2 inches. Remember, also keep your mower blade sharp so that the blades are cut cleanly and not chewed off.
You can find additional information about lawn care from University of Florida/IFAS researchers at http://edis.ifas.ufl.edu/topic_lawn_care