A turfgrass lawn appears lustrous green and beautiful, as long as they are healthy or disease free. Nevertheless, like any other plant, turfgrasses are susceptible to various plant pathogens, especially fungi. Very often, pathogens are present in the dormant state. They become active when favorable environmental conditions and susceptible grasses are present at the same time. Let's take a brief look at the common turfgrass diseases, how to identify and then control them.
Turfgrass Diseases
One of the basic thumb rules to prevent turfgrass diseases is proper maintenance of the turf with appropriate watering, aeration, fertilization and regular mowing. A slight alteration in the requirements makes turfgrasses more susceptible to several pathogens. In majority of the cases, outbreaks of turfgrass disease are most common in extreme environmental conditions like drought, excess moisture and very cold or hot temperatures.
Brown Patch Disease
Brown patch is a common turfgrass disease, which is observed during the summer months when there is high temperature and excess humidity. The occurrence of this disease is more in lawns that are maintained with high nitrogen fertilization. The causal organism for this turfgrass disease is Rhizoctonia solani. Like other turfgrass diseases, this fungus attacks the leaves and stem of the turf.
Identification and Control
If there are circular brown patches developed in the turf lawn, then the disease type is brown patch. A characteristic feature of the patches is the presence of a darker ring in the periphery of the patches. At times, the diameter of the circular patch exceeds more than a feet. The turf within the patch is thinned or killed completely.
Removal of accumulated dew on the turfgrasses helps in controlling further spread of brown patch disease. Another tip for the management of this fungal disease is to reduce the amount of nitrogen fertilizers added in the lawn. In addition, fungicidal sprays are recommended immediately after the onset of the signs.
Foliar Blight and Basal Rot Disease
Both foliar blight and basal rot of bluegrasses are caused by anthracnose (scientific name, Colletotrichum graminicola). This fungal pathogen attacks particularly the foliage and stem of most turfgrass species. The early sign of this turfgrass disease is an appearance of yellow or red lesions on the older leaves. As the disease progresses, the pathogens further attack the young leaves and stems as well.
Identification and Control
Foliar blight and basal rot can be identified, if irregular yellow or brown patches are present in the lawn. This disease is most commonly observed in extreme cold and hot temperature conditions. On peer observation, the fruiting bodies of the fungus can be seen from the diseased foliage and stems of the grass with the help of a magnifying lens.
Foliar blight and basal rot can be controlled effectively if identified in the early stages. Cultural lawn care like proper irrigation, fertilization and good soil helps in managing foliar blight and basal rot disease. Apart from this cultural control method, there are fungicidal sprays for killing the pathogens and/or preventing further spread of the diseases.
Dollar Spot Disease
Dollar spot disease in turfgrass is caused due to the fungus Sclerotinia homoeocarpa. Nearly all grass varieties are prone to this disease. Dollar spot occurs mostly during late spring or late fall. High humidity and low nitrogen level in the soil are some of the causes of increased susceptibility of the turfgrass to this disease.
Identification and Control
The affected leaves turn water soaked lesions that eventually become straw colored with brown margins. The spots are usually circular or irregular in shape. In the early stages, the spot size is small, about 2-3 inch. However, two or more spots may join to form larger patches. The symptoms are more noticeable in a recently mowed turf grass lawn.
A cultural control of dollar spot disease include maintaining optimum nitrogen level in the soil, removing morning dew and avoiding moisture stress. If the nitrogen level is low during the disease outbreak, it can be controlled by spraying nitrogen fertilizer lightly. A chemical control of dollar spot is spraying with appropriate fungicide in proper doses.
