University of Florida/IFAS Extension Director for Nassau County, Rebecca Jordi, answers questions about landscaping and gardening in northeast Florida.
QUESTION: My grass is dying, what is wrong? JD
JORDI: This month alone I have received about 10 calls on dead and dying grass. In all 10 instances the problem was caused by fungi which are directly related to the heavy rains, too much irrigation, poor drainage and/or the addition of high nitrogen.
Almost all cases had grey leaf spot which should not alone kill large patches of grass. However, I have also seen Take All Root Rot (TARR) which does just what you think it will do to the grass – take it all – root, stolon and blade.
Turn Off Irrigation
My first suggestion is to put irrigation systems on manual. There is no reason to be adding additional water on top of all the rain we have received. Turn your systems back on once you see we have no rain in the forecast. St. Augustinegrass prefers to be watered deeply but less often. ½ inch – ¾ inch at each watering once or twice a week in full sun (8 hours). Apply even less in shaded areas.
How will you know how much your irrigation system applies? You must measure it! If we water too frequently, the roots will become shallow and weak.
When To Fertilize?
We recommend using 15-0-15 fertilizer on April 15 and again on September 15. Please follow the directions on the label. Measure the lawn area, no reason to put out more nitrogen then the bag suggests. If you only have 2500 square feet of grass and the bag covers 10,000 then split it into 4 portions. ¼ in the spring, ¼ in the fall and save the rest for next year. Be sure to place it in a tightly sealed container to keep it fresh.
Bring Lawn Sample to Extension
If you want me to check your lawn grass bring in a sample from just outside where it is doing poorly. Bring in a shovels depth and width which must be dug up just before you come to the office. We conduct plant clinics the 1st and 3rd Mondays of the month (unless it is a holiday) at the Yulee satellite office. You can also call for a specific appointment at either of the Extension offices upon availability.