What Makes Grass Die in Ohio?

Moisture

• Watering Ohio-grown grass early in the day keeps moisture in and the lawn from drying in the sun. If the yard gets inadequate amounts of water, grass blades can wilt or die. Wilted grass blades dull in color and allow footprint tread to become more noticeable. Turfgrass such as Kentucky bluegrass (Poa pratensis), suitable for USDA zones 2 through 7, usually enters dormancy during drought periods but greens up when watered. Too much water can flood grass roots, depriving them of oxygen. Lawns should receive about 1 inch of water per week -- more during dry weather. Overwatering invites rots and fungal diseases.

Mowing

• Overgrown grass keeps turf and roots from receiving water and nutrients. Lawns may die if grass blades are cut too short and cannot develop sugars through photosynthesis. Kentucky bluegrass turf, for example, should be 2 to 2 1/2 inches high in spring and fall and 2 1/2 to 3 inches high during summer dry periods. Hot and dry summer temperatures may cause stress to lawns, which restricts soil moisture and weakens root systems. Cutting the grass higher allows soil to stay cool. Mow lawns as needed so that one-third of the leaf blade is removed per session.

Thatch

• Thatch forms in layers of dead and living roots, shoots and crowns between the soil and turfgrass. In Ohio, thin layers of thatch are not harmful to lawns, because they supply organic matter for earthworms to work into the soil. However, thickly tangled mats can limit the amount of water and nutrients grass receives, while encouraging disease and poor rooting. Thatch develops when grass plants grow faster than soil microbes can break it down. Grass may die if air, water and nutrients cannot easily move in the soil.

Chemicals

• Fertilizing lawns with nitrogen, phosphorus and potassium allows grass to grow and helps to keep weeds out. Depending on soil test results, Ohio lawns generally respond well to a 5-1-2, 4-1-2 or 3-1-2 fertilizer mix, advises Ohio State University Extension. If nitrogen is released too fast or spread too thickly during one application, fertilizer can burn and possibly kill turfgrass. To avoid chemical burns, fertilize dry lawns evenly, and then water granules directly into the ground. Seed-germinated weeds and crabgrass (Digitaria spp.), common in Ohio lawns, typically grow in the top one-half inch of the soil but not too deeply into grass roots.

  Preemergent herbicides containing siduron, bensulide or oxadiazon in liquids or granules are often effective but only if they are applied before weed and crabgrass seeds germinate in early spring. Water preemergent herbicides into the lawn at least 7 days before the expected start of weed-seed germination; when soil temperature reaches 60 degrees Fahrenheit. Chemical solutions containing methanearsonate are suitable for killing established weeds and crabgrass, which generally appear in late May for southern Ohio and mid-June for the northern part of the state. Apply postemergent herbicides as soon as possible to prevent weeds from spreading. Depending on plant growth, two doses of weed killer applied one to two weeks apart generally control crabgrass, but more treatments may be necessary if seeds continue to germinate. Follow label instructions on all premixed herbicides.

Disease

• Ohio lawns are susceptible to various diseases that may kill or merely damage turfgrass. Summer patch (Magnaporthe poae) features round or variously shaped swaths of strawlike yellow grass, usually developing within one to two weeks. The fungus attacks rhizomes, stolons and roots in the spring, especially if soil pH is 6.5 or higher. Poor water drainage, heat stress, drought and soil compaction may lead to summer patch, especially if grass is cut too short.

  Several types of fungi produce powdery mildew (Erysiphe graminis), a grayish-white dusty substance that develops on grass and flower-plant leaves and stems. Powdery mildew is not typically fatal to lawns, but severe cases can damage the grass blades. Red thread (Laetisaria fuciformis), which grows in temperatures of 40 to 80 degrees Fahrenheit, displays thin streaks of reddish-brown on grass blades. It may be mixed with pink patch (Limonomyces roseipellis), a cotton-candylike puff of fungal spores. Rust diseases (Puccinia spp.) produce thin reddish-orange or yellow streaks that are not highly visible on cool and warm-season grasses. However, severe infections may weaken the lawn and allow stresses such as drought or severe heat to kill grass roots.