Q. Funny yellow spots are appearing in my fescue lawn. I haven't sprayed anything. What could this be?
A. Our summer weather may be the problem with your sod and with many of the lawns all across our area. Many different fungus diseases can appear when there is afternoon and evening rainfall, especially heavy rainfall with high temperatures or even unseasonably low temperatures. We've certainly had that kind of weather.
You will have to inspect the places where you see the problem by looking carefully at single blades of grass (maybe with a magnifying glass), by checking the soil moisture (is it squishy?) and by examining your mower blades and setting. Look at individual grass blades up close and try to find small spots, streaky rust-colored strips or moldy-looking areas. Then you know it is a fungus problem.
There are lawn fungicides that can help to correct this, but unfortunately, if the wet weather continues, your lawn may require several sprayings and more careful maintenance. If the soil itself stays squishy from rain, you can counteract this by aerating with the kind of aerator that takes plugs out of the soil. This can often solve many grass problems since sod can be compacted over time with use, and the roots suffer.
If the tips of each grass blade are shredded, uneven and brown, your mower needs to be sharpened. Torn grass turns into sick grass very quickly. Sharpen those blades; mow, don't shred. Mow frequently when rains make the grass grow quickly.
You should never remove more than 1/3 of the blade of grass. You can shock and weaken grass by letting it grow tall and then scalping it. Mow fescues between 3 and 4 inches tall and Bermuda and zoysias from 1 to 1 1/2 inches. Mowing at the correct height prevents weeds and keeps the grass healthy.
If your grass has sustained a lot of damage, plan to overseed in September.
Contact Pat Lea at firstname.lastname@example.org.