|
Prev. Next The list below shows items 11601 to 11800 of 32208 total items: Prev. Next Top of Page |
Patch Diseases
Patch diseases will occasionally occur in bluegrass lawns. Areas of turf die in patches, hence the name. Advanced stages of the disease appear as rings of dead turf surrounding living turf that resembles a "frog's eye". Researchers have identified several fungi that cause patch-like symptoms. Some of the more common patches include summer patch, yellow patch and necrotic ring spot. Necrotic ring spot and yellow patch are active during cool weather in the spring and the fall, but patches may remain into the summer months. Summer patch is active during the summer period. Once established, these diseases are extremely difficult to control, and tend to occur in following years. Red thread and pink patch are diseases that attack Kentucky bluegrass, fescues, rye grass, and bent grass. These diseases are active during the cool, moist periods of the year, causing distinct-to-irregular discolored patches to develop in lawns. The leaves often become covered with a pink, fibrous growth. In the final stage, reddish fungal threads are found at the leaf tips. In a lawn infested with red thread or pink patch, pink areas from two to fifteen inches in diameter become readily apparent. These spots may join to form large areas of damaged turf. Areas may turn brown and dry out. These diseases are most common under the combination of prolonged periods of high humidity, temperatures between 60°F to 75°F, and slow-growing, nitrogen-deficient turf. Controlling Red Thread and Pink Patch
Patch Diseases of Cool-Season Turfgrass Patch diseases can be very damaging to most cool-season turfgrasses. These diseases cause circular patches of dead turf, which may surround turf that is still green. This "frog eye" symptoms often occurs with this group of diseases. Patch diseases generally occur on sodded lawns, especially within the first 5 years of establishment. However, older lawns either established from seed or sod can also develop patch diseases. Several fungi cause patch diseases. The actual fungal pathogen will depend on the specific patch disease. The more commonly occurring patch disease include the following:
Initial symptoms appear as small spots (2 - 4" diameter) of light green turf. Spots enlarge to form light straw colored circles, irregular patches, and crescent patterns that are 1-2 feet in diameter. Centers of the patches may contain grass that is alive or dead. When dead, the patches of grass appear crater like or sunken. Patches may overlap to form large areas of blighted turf. Symptoms may also appear as diffused patterns of yellow or brown turf. Blackening of the infected crowns, rhizomes, and roots is also characteristic. Yellow patch on bent grass generally occurs as yellow rings that often recover. Conditions That Favor Diseases
Control of patch diseases is very difficult, and often unsuccessful. Patch diseases are more damaging if the lawn is improperly mowed and watered. Properly maintaining the turf will reduce damage and help in control. During turf establishment, good soil preparation and selection of quality sod or seed are preventative measures. Core aeration to assist in better turfgrass rooting will help in preventing disease and aid in recovery. Renovation of the diseased turf often is necessary. Tips to help avoid patch diseases:
Winterkill and Snow MoldWinterkill is a general term used to described injury of turf in the winter. Winterkill can be caused by many things, including low-temperature injury, winter dehydration and fungal diseases. Low-temperature injury occurs when grasses, which have not hardened-off, are exposed to below-freezing temperatures. Warm-season grasses are more susceptible to low-temperature injury than cool-season grasses. Freezing and thawing in late winter accompanied by high soil moisture is a common cause of low-temperature kill. Winter dehydration occurs primarily in Northern regions under prolonged periods of cold and windy conditions with little or no snow cover. Snow mold is a disease that also occurs mostly in Northern
regions. It is caused by several different fungi and affects many turfgrasses.
The symptoms are irregular to circular patches of water-soaked, yellowed,
or bleached turf. They sometimes bear a whitish, gray or pinkish cast.
Snow mold commonly becomes noticeable after a period of snow cover over
unfrozen soil. Horticultural OilTreating with horticultural oil involves injecting essential nutrients into the root zone. Surface drench or dry nutrients may be used under certain situations. Insect and/or mite controls are applied as young foliage develops. This treatment minimizes early season damage caused by insects, mites and diseases. It also helps to control certain pests during their overwintering stage, before damage occurs. Horticultural oil enhances color, improves leaf size, while stimulating overall growth and flowering potential. Top of Page Leaf SpotLeaf Spot Melting Out Leaf spot is one of the most common turfgrass diseases. It occurs most frequently during cool, moist weather and causes yellowing and severe thinning if it's not controlled. Leaf spot begins as small, dark spots on the leaves and leaf sheaths. As the spots enlarge, they turn purple with a tan center. If the disease persists, the spots may cause a collapse of the plant, leading to a thinning or "melting out" of the turf. While the problem is active in the spring, the thinning may not occur until summer. Controlling Leaf Spot Proper watering, mowing, and fertilization are essential. * Water deeply but do not keep the grass continuously wet or allow it
to become excessively dry. Source: our affiliate partner: Acme Hardware |