Both St. Augustine and Bermuda are relatively unaffected by diseases and insects. However, here's how to identify the most common problems and correct them:
- Brown patch – If St. Augustine grass leaves turn brown and die at the leaf base, the cause could be brown patch. To test for this fungal disease, pull on a leaf blade; if it easily comes loose from the runner, it’s brown patch. Affected patches will be 1 to 5 feet in diameter. To discourage this fungus, avoid watering St. Augustine during the afternoon and immediately discontinue any synthetic fertilizing. Spraying with baking soda and water is a good organic solution. Synthetic controls include PCNB (Teraclor) or cholorthalonil (Daconil 27897).
- Gray leaf spot – Small yellow patches with black interiors, resembling a cigarette burn, are an indication of gray leaf spot. Follow the same watering and treatment guidelines for brown patch.
- Chinch bugs – When your sod appears to be wilted or needing water, but watering does not restore the foliage, you need to check for chinch bugs. The damage will be especially noticeable during the hottest days of summer and in the hottest part of your yard. Chinch bugs are difficult to see because of their small size, but if left uncontrolled they will kill these areas of your lawn as they literally suck the life out of grass. The adult is about the size of a gnat with a gray body and a distinctive black diamond on the back; the immature insects are black and even smaller.
For organic control, any pyrethrin-based product works well. Although natural, these products will kill any insect so use sparingly and only on affected areas. Synthetics are readily available but are especially toxic.
- Grubworms – When the foliage and upper root system of your grass can be lifted off the ground like the toupee off a bald man, this is a clear sign of grubworm damage. Not all grubworms, which are the immature form of beetles, are destructive to your lawn. "Good" grubs will have a head noticeably larger than their tail while the reverse is true for "bad" grubs. Being able to distinguish between the two is important because the good grub preys upon the bad. The treatment is the same as used for chinch bugs: careful use of pyrethrin-based products.