Prevention is key
A beautiful lawn takes time, patience, proper care and a never-ending watchful eye. The following lawn care tips can reduce many lawn problems:
- Do not over fertilize to promote fast lush growth, especially in hot, humid weather.
- Collect clippings to avoid thatch (layer of living and dead stems, leaves and roots of grasses which develops between the layer of green vegetation and the soil surface) where certain disease causing organisms and insects thrive.
- Maintain adequate soil moisture with infrequent but deep watering. Light, daily water-rings favor many disease causing organisms.
- Maintain the proper soil pH. If in doubt, obtain a soil analysis.
- Keep the lawn clipped at the proper height. Too short a cut will weaken the grass and make it susceptible to a disease, and too tall a cut will hold moisture so the grass fails to dry rapidly.
- Mow frequently so that not more than 1/4 to 1/3 of the total leaf surface is removed each time.
- Remove thatch when it accumulates to 3/4” or greater.
- Mow the lawn throughout the fall until the, grass stops growing.
Act fast when you suspect a problem
Carefully inspect your lawn periodically throughout the growing season. Be on guard when a lawn problem arises. Many problems, if corrected early, can be remedied. During the growing season keep a watchful eye for:
- Brown or dead spots: The season of the year in which they appear and previous lawn practices may be clues to the problem.
- Fertilizer burn: When was fertilizer last applied? How much? Look for brown spots or streaks where heavy applications may have been made (around trees, shrubs, etc.). A uniform brown cast may be fertilizer burn. Fertilizer may burn if applied when the grass is wet and the fertilizer is not washed off immediately.
- Disease: Certain species of grass are more susceptible to given diseases than others. Bentgrass often gets Dollar Spot in May, June, September and October. Common Kentucky bluegrass is susceptible to Drechslera Leaf Spot and may be seriously affected; the entire lawn will appear brown after mowing. Some areas may be more seriously affected than others. A black slime mold may develop on grass during wet weather.
- Insect damage: Grubs may kill large areas of a lawn. Worst damage shows up in late summer. In affected areas, the sod can be rolled back like a carpet to reveal the grubs. Extensive bird and skunk feeding are signs of grubs. Sod Webworms live in the sod and feed on the leaves and stems at night. The worms chew grass blades off just above the thatch line, pull the blades into their silken tunnels and eat them. Injury appears as circular or irregular brown patches of close-clipped grass. Where webworms are abundant, numerous small holes (diameter of one’s finger) are often found in the dead patches. These holes are made by blackbirds seeking out the large sod webworms. Chinch Bugs may be a problem when the weather is hot and dry. Large brown areas occur in sunny areas. Look for the bugs in the circle of grass that has turned yellow around these dead patches.
- Annual bluegrass: It is the nature of annual bluegrass to die during the summer. Dead annual bluegrass is often mistakenly called “disease.”
- Dry spots: Punch the affected spots and adjacent green area with a knife blade or screwdriver. If the brown spot is hard and the green area soft, a lack of moisture in the brown spot may be the reason. Local dry spots occur because of poor condition, thatch, fungal growth in soil or other unknown causes. Bentgrass patches usually turn brown first in an otherwise Kentucky bluegrass lawn.
- Gasoline spillage: Petroleum products will kill grass.
- Mowers in poor condition: Dull mowers or mowers improperly adjusted may crimp the grass instead of cutting it. The dead leaf tips will cause a general browning. Mowers in poor condition may cause grass to fray. The grass will show a white cast and then brown on the tips.
- Female dogs: Female dogs may cause green or brown spots on a lawn. The larger a dog, the drier the soil, and the higher the temperature, the more damage will be done. In or around the affected spot, the grass not killed will turn green because of nitrogen in the urine.
- Improper use of pesticides or other chemicals: Herbicides for controlling crabgrass, insecticides or fungicides can cause burn or brown spots to occur.
Author: John F. Baniecki, Ph.D., Extension Specialist, Plant Pathology and Entomology: From the Pests of Ornamental Series
Last Reviewed: May 15, 2017 by Rakesh Chandran, WVU Extension Specialist, Integrated Pest Management