WHAT IS WRONG WITH MY LAWN?
Lawn problems can occur in small areas or large patches, the entire lawn can die. Sometimes the problems are due to poor growing conditions, improper lawn care practices, or extreme weather conditions. Other problems can be due to specific insects, pests, or diseases.
The following list is a guide to help you decide what conditions might be causing your problems, with some suggestions for preventive and corrective measures.
After Winter, But Before Spring Green-Up
Winter desiccation - large areas of straw colored grass, especially where exposed to wind.
Spring frost damage - New leaves killed back
Water and ice damage - straw colored or rotted grass, especially where water collects in frozen soil.
Snow molds - white, pink, and gray mold in circular patches on moist grass.
Salt damage - dead or yellow grass along sidewalks, driveways, or roads where salt is applied.
- Avoid snow molds by mowing as long as grass grows in the fall.
- Avoid mid-fall nitrogen applications that delay dormancy.
- Prevent deep piling of snow along walks and driveways.
- Try sand, cat box filler, etc. as a substitute for deicing salt. Avoid salt when possible.
- Rake away dead grass.
- Reseed thinned or bare areas when soil is well drained and warm.
- Water heavily to try to wash away salt if damage is from salt.
After Spring Green-Up
SOIL PROBLEMS AND CORRECTIVE MEASURES
- Soil is hard, turf is thin. Rooting is poor.
- Add organic matter during lawn reconstruction.
- Reroute foot traffic and play areas to avoid frequent packing down of soil.
Circular patches and/or rings of dead and/or unusually green grass:
Note size and patterns.
In the morning when grass is still dewy, look for web like threads of fungus and or mushrooms on the lawn.
INSECT PROBLEMS AND CORRECTIVE MEASURES
Gradually increasing patches of thin turf, often looks like drought stress. Sometimes accompanied by skunk, raccoon or crow damage. Usually observed in April and May or in September and October.
Generally observed in sunny areas or on sandy soils. Usually observed during hot periods in July and August.
Sporadic in New England, usually begins as yellow areas along the edges of driveways and sidewalks. Damage usually observed in July or August.
Improper fertilizer applications:
Over and under-fertilizing can result when spreader is not calibrated properly or when application pattern is not carefully followed. Take special care when turning with spreader. Brown streaks lined with extra green growth can occur in areas of application overlap.
- Spots of brown – dead looking grass.
WATER PROBLEMS AND CORRECTIVE MEASURES
- Water deeply when necessary
- Water early in the day so foliage will dry up quickly. Night watering is not recommended during hot, humid weather because of potential for disease development.
Too little water:
- Wilt, browning, death. Will green up when moisture returns.
Too much water:
- Deprives roots of oxygen, stunts growth, and promotes root and crown rots.
- Water less frequently. Correct drainage if necessary.
LIGHT PROBLEMS AND CORRECTIVE MEASURES
- Most lawns will be thin shaded areas.
- Selective pruning of tree and shrub branches may let in enough extra light to promote grass growth.
- Plant shade tolerant turf grass cultivars or other groundcovers in heavy shade.
- Increase mowing height.
- Decrease fertilizer application rate.
Too much thatch:
Thatch forms when stems and roots are produced and then sloughed off by the turf grass plant faster than they can break down. Clippings left on a lawn do not contribute significantly to thatch buildup.
Remove thatch layer if greater than ½ in. thick because excessive thatch prevents grass plants from absorbing nutrients and water properly, may provide a harbor for pathogens and insect pests.
MOWING PROBLEMS AND CORRECTIVE MEASURES
- Mow lawns at 2” to 3”, with maximum in hot, dry weather.
- Avoid “scalping” especially in irregular, bumpy areas.
- Remove no more than 1/3 of total length at a cutting so grass is not stressed.
- Can generally be left except during a disease outbreak or if they tend to “clump” on the lawn.
- If grass blades look blades look brown and shredded, sharpen and adjust blades.
DISEASE PROBLEMS AND CORRECTIVE MEASURES
General practices that reduce disease:
- Keep foliage dry as much as possible.
- Mow when grass is dry.
- Landscape to allow good air circulation.
EFFICIENT WATERING OF TURF
It occasionally becomes necessary to provide supplemental irrigation to keep turf grasses growing well, especially during the summer months. Water is lost from the soil by gravitational drainage, evaporation, and plant use. If plant or soil water content becomes limiting, drought stress and/or turf grass death may occur.
WHEN IS IRRAGATION NECESSARY?
Many variables influence the amount of water used by turf grasses. These include: humidity, temperature, grass species, and rate of growth. Rooting depth and soil texture also affect turf grass water needs. More deeply rooted grasses can extract water from a greater volume of soil and are thus more drought tolerant than shallow rooted species. Finer textured soils hold more water than course soils and require less frequent irrigation. Because so many factors interact to determine turf grass water use, it is difficult to give a general estimate of how often to water a lawn. The best technique for determining when to observe both soil and plant conditions in the lawn and then water when the turf needs water rather than based on the calendar.
DETECTING WILT AND DROUGHT STRESS
In order to conserve water and avoid the detriments of over watering, lawns should be watered just prior to the development of wilting and drought stress. This may be difficult to determine initially, but a little knowledge and experience will make it easier.
Wilting occurs because the plant's internal water contents drops so low that the plant cannot remain turgid, and plant cells begin to shrivel. Turf grasses undergo a series of visible changes when they begin to wilt. Development of a bluish-green coloration and the rolling or folding of leaf blades are two noticeable changes associated with wilting.
If footprints remain visible on the lawn for several minutes after walking on it, the turf is not very turgid and wilting is imminent. These initial symptoms of wilting will not cause permanent injury to the lawn. However, they do indicate that the lawn should be watered soon in order to avoid drought stress and possible turf grass death. In addition to observing plant symptoms, examining the soil is also helpful in determining when to irrigate. Use a soil probe or garden spade to examine the soil to a depth of approximately six inched. If the soil appears dry, it is time to water.
EFFECTIVE WATERING PRACTICES
Frequent lawn watering often encourages shallow rooting and may predispose the lawn to increased disease and greater susceptibility to stress injury. Watering deeply and less frequently provides for improved turf growth and increased water conservation compared to light, frequent watering.
GROWING TURF UNDER SHADED CONDITIONS
In order to grow turf under shaded or partially shaded conditions, it is necessary to understand both the detrimental effects of shade as well as cultural practices, which can be used to minimize those effects.
REDUCTION OF LIGHT
Although buildings and other structures may shade turf, trees are generally the most common cause of shade. The most obvious impact of shade is a reduction in the amount of light available to the turf. Grasses, like all green plants, convert light energy into carbohydrates via a process known a photosynthesis. These carbohydrates serve as the building blocks and energy source for plant growth and development.
In addition to reducing the total amount of light available, tree shade also severely limits the amount of useful light reaching the turf. All wavelengths of light are not equally effective in photosynthesis. Green plants absorb primarily orange, red, and blue light while reflecting mainly green and yellow. Therefore, the majority of light reaching shaded turf is likely to be light, which has filtered through the tree canopy and is low in those wavelengths most valuable in photosynthesis and carbohydrate production.
Aside from altering the light reaching the turf, trees also produce surface roots, which compete with the grass for nutrients and water. This competition further inhibits the grasses' ability to grow. It becomes very difficult to maintain a turf of desirable quality. Exclusion of rainfall by tree canopies can dispose shaded turf to drought stress, a situation that is often overlooked when assessing shade effects. Increased relative humidity and decreased air circulation in wooded areas favor the development of turf grass diseases such as powdery mildew and also encourage moss and algae problems.
Since trees are the primary cause of shade, intelligent tree management practices are essential to minimize shade problems. Decline of turf growing under trees may occur gradually over a number of years. As trees grow their canopies become wider, thicker denser, and their roots increase mass and spread. Consider removing trees and shrubs, which do not contribute, meaningful to the landscape design. Pruning tree limbs, which grow at heights below eight to ten feet, can often substantially improve the amount of morning and afternoon sunlight reaching the turf. Also, selective thinning of the tree canopy itself will allow more photosynthetically useful light to penetrate to the turf.
Planting of shallow rooted trees such as willow, silver maple, cottonwood, sweetgum, etc. should be avoided if possible in order to reduce nutrient and water deficits due to root competition and to avoid future impediments to mowing.