SOLUTIONS TO COMMON LAWN PROBLEMS
Spring
Depending on your location and situation, you may encounter a number of problems come springtime. Your very first problem may be a weed infested lawn. However, if you plan ahead, you can prevent a number of common weed problems before they start. A good idea may be the application of preemergent herbicides. Preemergent herbicides are used to control weeds by forming a chemical barrier at the soil surface that inhibits the germination of various grassy and broadleaf weed seeds. The timing of this application will vary from location to location, but here in Ohio tends to run anywhere from mid March to early April. (One important consideration to note is that preemergent herbicides should not be used on newly seeded lawns because of their germination-inhibiting effects). If, however, it is too late for preemergent application to be effective, you will want to consider using a post-emergent herbicide. A non-selective herbicide such as glyphosate works well for pesky perennial weeds, but it also kills grass as well. In a lawn situation, I would recommend using a selective herbicide. These herbicides work in such a way that they will not harm most grasses if used at the appropriate rate and time of the year. Most importantly, however, is to keep in mind that the best defense against springtime weeds is a thick, well maintained lawn.
Another possible lawn problem that may be encountered during the spring-time months is disease. Many factors contribute to turfgrass disease including improper cultural practices such as improper fertility, poor drainage, and poor air circulation. Grasses vary in their susceptability to diseases and some have even been developed such that they are resistant to common pathogens. Here are some of the springtime diseases you may encounter on perennial ryegrass, kentucky bluegrass, fine or tall fescue, or bentgrass lawns:
Pink Snow Mold (Microdochium nivale)- This disease can occur on most all species of cool season lawn grasses. It is especially prone to occur on newly seeded lawns in which a high seeding rate and high nitrogen fertility have been used. The pathogen thrives on lush, succulent turf and forms patches with pink borders ranging from 2" to 12". It is only a foliar pathogen and thus, does not effect the crown (growing point) of the turf plant. The pathogen us can be active from late fall through early spring and thrives in 32-45 degress F, wet, cloudy weather.
Red Thread (Laetisaria fuciformis)- Red thread is a common problem in both the spring and fall on all of the above species, but especially perennial ryegrass. It is favored by periods of prolonged moisture-saturated air. For example heavy dews, rain, and fog are extremely conducive to disease development. This pathogen typically infects underfertilized, slowly growing grass. Interestingly, Red thread has been reported in every month of the year. The disease leads to the appearance of circular of irregularly shaped patches 2"-20" in diameter. The pathogen produces a pind to red mycelium during favorable periods that gives an overall pink appearance to the dead patch of infected grass.
Powdery Mildew (Erysiphe graminis)- This pathogen is especially fond of Kentucky bluegrass growing in the shade. It is an important disease of many plants which grow in low light intensity and poor air circulation. However, it also affects the fescue species as well. The pathogen produces a white mycelium that gives the turf the appearance that someone has literally "painted it white". Although powdery mildew fungi commonly affects ornamentals, vegetables, and cereal grains, the turf-affecting pathogen is a cousin to these pathogens.
SUMMER
Summer time can be a stressful period for turfgrass growth. Both soil and air temperatures exceed the optimal levels for desirable turfgrass growth and rainfall is at its lowest amount of the year. Thus, in most lawns, a mechanism takes place within the plant to avoid this stressful period. This mechanism is called dormancy. It is the reason that the grassplants turn straw color and the plant growth stops. However, in irrigated home lawns, this process can be avoided and a green lawn is very much apossibility throughout the droughty, hot summer months. Because the turf is under so much stress, both irrigated and non-irrigated homelawns can undergo severe disease pressure during these times. Thus, it is important to know and recognize the symptoms and factors that can lead to development of various diseases:
Dollar Spot (Sclerotinia homeocarpa)- Dollar spot is the most sprayed for disease in the Ohio during the summer months. It is typically found to occur on all turf species, especially those that are underfertilized with nitrogen. The pathogen causes sunken, straw to bleach colored patches from 1'" to 8" in diameter which may coellesce to form larger patches. Because dollar spot is only a foliarpathogen, the patches will come back with the onset of cooler temperatures and rain.
Pythium Foliar Blight (Pythium aphanidermatum)- Pythium is quite possibly the most destructive turfgrass disease. It has the capability to destroy an entire lawn within days. All turf species are susceptible to attack by the pythium fungus. The pathogen requires water to reproduce and can spread extremely fast in hot, poorly drained lawns during times of high humidity. Excessive nitrogen fertility has been shown to increase pythium succeptibility. Pythium produces orange or bronze patches that spread along drainage patterns and via foot and mower traffic. Because this fungus requires water to germinate, drainage isabsolutely essential for preventing this disease.
Brown Patch (Rhizoctonia solani)- Brown patch is another serious disease that, like pythium, attacks both the leaves and crowns of plants. It too, is favored by hot, humid conditions. In addition, it also is favored by high nitrogen fertility. It is characterized by forming blighted patches of turf that are bordered by a smoke colored ring which can often be seen in the early morning hours. The pathogen produces only mycelium, which when trafficked upon will cause rapid spread of the disease. Typically, this is a disease of perennial ryegrass, tall fescue, and sometimes kentucky bluegrass in home lawn situations.
Anthracnose Leaf Blight (Colletotrichum graminicola)- Anthracnose is a disease that occurs throughout the world on almost all species of grass. It is especially a devastating disease of annual bluegrass. This disease typically occurs on lawns that are under a high degree of stress. This stress may be related to a number of factors ranging from poor fertility to compaction to drought stress. It commonly occurs on dry soils when atmospheric humidity is high and temperatures warm. Anthracnose causes oblong, reddish brown leaf lesions that turn yellow then tan then brown, and finally die.
Other common problems that may arise during summertime months are weeds. Weeds such as crabgrass, foxtail, and goosegrass are common to this part of the country during July and August. If you find yourself in a battle against these weeds during these months, rest assured, their are a number of product out their for grassy weed control. Be careful, however, to follow label instructions when using these products in the heat of the summer. It is usually best to spray for these weeds when cooler days persist. Hot temperatures can cause even the safest herbicides to be phytotoxic to lawn grasses.
FALL
Fall in this part of the country is perhaps the most beautiful time of the year. As many plants are beginning to shut down for the year, soil and air temperatures are beginning to cool off and precipitation is providing the needed push to help the lawn look its best. The month of September is an optimal time for renovation of damaged areas or perhaps the entire lawn. You may, however begin to notice patches or larger areas of the lawn that don't seem to want to green up. If you find that these straw colored areas don't green up by October, chances are they have suffered damage from grubs. The most common method of diagnosing this problem is to lift up on the dead areas of turf . If they lift up like a rug, you will very likely notice grubs on the soil surface. The reason this turf has died is that the grubs have destroyed the roots of the turf by feeding on them all spring and summer. Although there is not much that can be done now, you may want to spread an insecticide in the affected areas. You may want to wait until the following spring to apply this so that the young, feeding grubs will be better controlled by the application.
Fall is also the best time of the year for weed control, especially perennial weed control, which are transporting nutrients and energy down into the roots of the plant at this time of the year. This makes weeds more susceptable to herbicides in the fall than at any other time of the year.
Finally, disease pressure is usually significantly lower than the summer months. A few of the most common lawn diseases to occur this time of year (September - December) are the following:
Powdery Mildew (Erysiphe graminis)- This pathogen is especially fond of Kentucky bluegrass growing in the shade. It is an important disease of many plants which grow in low light intensity and poor air circulation. However, it also affects the fescue species as well. The pathogen produces a white mycelium that gives the turf the appearance that someone has literally "painted it white". Although powdery mildew fungi commonly affects ornamentals, vegetables, and cereal grains, the turf-affecting pathogen is a cousin to these pathogens.
Rust (Puccinia graminis)- This pathogen, as its name implies, appears as a rust colored cast on the grass blades during early fall. The dust-like rust spores form in circular or elongated groups on the grass blades. This disease spreads easily by shoes, mowers, and other types of traffic. It thrives in warm, moist, weather, typical of September in Ohio. Rust affects most all lawn grasses, but particularly Kentucky bluegrass and annual ryegrass. Rust often occurs on under-watered and under-fertilized lawns. There are many new cultivars of Kentucky bluegrass and Perennial ryegrass that havehave been developed resistant to the fungus.
Leaf Spot (Drechslera diseases)- This disease, which can occur in the spring or fall is also refered to as melting out. The fungus primarily attacks Kentucky bluegrass and fescues. Symptoms appear as elongated, circular lesions on grass blades. The center of these lesions is straw-colored and the borders are a purple color. Cool, moist, shady stands of Kentucky bluegrass are especially prone to this fungus.
WINTER
During the winter months, lawns go into dormancy and are rarely under much biotic disease pressure due to the colder temperatures. However, there are two common pathogens that can affect turf during the winter months in states like Ohio on northward:
Pink Snow Mold (Microdochium nivale)- This disease can occur on most all species of cool season lawn grasses. It is especially prone to occur on newly seeded lawns in which a high seeding rate and high nitrogen fertility have been used. The pathogen thrives on lush, succulent turf and forms patcheswith pink borders ranging from 2" to 12". It is only a foliar pathogen and thus, does not effect the crown (growing point) of the turf plant. The pathogen us can be active from late fall through early spring and thrives in 32-45 degress F, wet, cloudy weather.
Gray Snow Mold (Typhula incarnata)- Gray Snow Mold, or Typhula Blight typically affects grasses in colder climates than does pink snow mold, although each can occur simultaneously. The pathogen thrives on much the same conditions and grasses as does pink snow mold. However, this pathogen requires snow cover for growth and spread, whereas pink snow mold does not. It too, is a foliar pathogen, so affected areas will generally recover come springtime.
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