Dark brown streaks in lawn

Asked October 22, 2016, 11:48 AM EDT

Following the heavy rains in August, I noticed long streak of dark brown grass in my lawn. It appears to have spread. I've read that the problem could be grubs, thatch, or a fungus. I have attached a couple of pictures to illustrate. Could you please identify the issue(s) and advise me on possible solutions? Thank you, Jarrettsville ,

Harford County Maryland

1 Response

We cannot say for sure what the problem is. We do not have enough information how the turf has been managed. Some reasons for the brown spots may be planting the wrong turfgrass species, poor soils, fertilizer injury, close mowing, brown patch, grubs, etc. See our website for more information http://extension.umd.edu/hgic/cultural-environmental-problems-lawns
Turf type tall fescue is the recommended grass species and grows best in full sun to part shade. If you planted a contractors mix of different species at some point, some of the grasses may be dying out. Also, Some grass species can go dormant at different rates during hot, dry weather. Poor soils - not enough organic matter in the soils to promote root growth, or close mowing.
Brown patch is a common summer disease of cool season turfgrasses. Temperature and humidity favor this disease. Avoid spring applications of fertilizer. Apply fertilizer in the fall. Most turf recovers in the fall with a return to rainfall and the proper fall fertilization.
See more on brown patch http://extension.umd.edu/hgic/brown-patch-disease-maryland-home-lawns

Grubs - Make sure you have a grub problem. Reasons include past history of grubs, if you have a sprinkler system that keeps the soil moist for egg laying, and if we have weather conditions like wet summers and lush lawns while the adult beetles are active in June. The turf can be rolled back from the soil like a rug this is usually in late summer to early fall. Look for grubs in the upper soil surface, you may need to dig with a trowel. If the grub count exceeds 6-8 per square foot, you may want to consider treating for grubs. However, It is too late for this season. The grubs will be going lower in the soil profile.

In general, adult egg laying begins in July and root feeding begins in August. Grub controls are applied as a preventative (time frame is mid June through August). Look for a season long grub control that contains the active ingredient Chlorantraniliprole. This product is more environmentally friendly. See our publication on japanese beetles for more information http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG78%20Japanese%20Be...

You may have to do some spot renovation or overseeding. The best time to do this is late August through mid October. It is getting late and if you seed this will be a gamble with Mother Nature. Tall fescue seedlings can be damaged by frost. You also have to consider leaves falling, etc. The second best time to seed is early March through April.

Test your soil if not done in the last several years. Results give pH, liming, and fertilization recommendations. https://extension.umd.edu/hgic/soils/soil-testing

See our publications on lawn renovation and overseeding and our turfgrass maintenance calendar for more information on maintenance and care throughout the year.