Q: I am having an unusual problem with my centipede lawn. Our lawn was planted in the spring of 2008. It appears to be healthy.

But purple streaks begin to appear a few days after I mow. The streaks are where the riding lawn mower tires go.

A: Turf expert Clint Waltz says:

“Centipedegrass will readily produce anthocyanin, the pigment within leaves that give the pretty red, orange, and yellow leaf colors on trees in the fall. For centipedegrass, this is typically a response to a stress, in this case traffic.

“I’ve seen it many times as a response to stresses like traffic, wear, drought, low fertility, pest attack, etc. The red color is an indicator there may be a problem, but if you remove the stress the color disappears.

“Vary the mowing pattern and don’t follow the same tracks each time. Mow at right angles and perpendicularly to the pattern seen here. Also avoid mowing when the grass is drought stressed. This is not a major concern and will disappear on its own as new growth replaces older leaves.”