Why is my lawn looking worse now than at other times of the year?
This summer has brought excessive heat, rain and high humidity to our area. All three factors place stress on the root system and leaf blades of our turf during this period. On top of the daytime extremes, when nighttime temperatures do not drop below 65°, our lawns simply never get relief and the turf is under a constant state of stress. Here are some things we are currently seeing in our lawns:
LATE-SUMMER CRABGRASS – Late spring and early summer crabgrass has been controlled by the pre-emergent application applied in the spring time. That period is now behind us. Some late-summer crabgrass is now showing up, especially in areas of bare or thin turf and near edges where added heat stress from asphalt/concrete surfaces add further stress to our cool-season turf varieties.
Why? Our soil in most of this region is not accustomed to receiving the amount of rain fall we are experiencing this year. That causes major issues with soil and the wash out of any lasting pre-emergent designed for late summer protection. The result is more than usual crab grass outbreaks in those sensitive areas.
A good fall frost/freeze will kill off these late-season plants. In the meantime, plans should be made to rejuvenate the weaker areas of turf with appropriate fall renovation. This may include a thorough raking and seeding, core aeration and over seeding, or power seeding. Late-August through mid-October is the prime window of opportunity for successful renovation.
DALLIS/JOHNSON GRASS – These two undesirable grasses look a lot like crabgrass but are actually clumping field grasses that cannot be controlled with normal herbicide products. Dallis and Johnson grasses both thrive in hot, moist conditions. The top growth will die back with the first frost. Tubers may survive to next season.