Brown Patch Lawn Problems

Now that Labor Day has come and gone and with fall right around the corner, there is a common disease that shows up in lawns here in Louisiana, brown patch. Brown patch is a common, soil-borne fungal disease that attacks warm-season grasses and usually shows up in the fall when the temperatures begin to cool and grasses are preparing to go dormant for the winter. The disease occurs in a variety of grasses that we have here in Louisiana. Such grasses include bermuda, centipede, and St. Augustine, which is the most susceptible to the disease here in Louisiana. Other warm-season grasses are not immune to the disease and can be heavily damaged by this disease. Resistant varieties of grass are not available.

As the temperatures cool and the moisture level increases in the fall, the disease starts to be present in lawns throughout Louisiana. Brown patch develops most rapidly when the nighttime temperatures range from 60-75 degrees F and the daytime temperatures do not exceed the 85-90 degrees F temperature mark. With these temperatures and Louisiana’s humidity, our area is an ideal breeding ground for this disease.

The first symptoms of the disease will be yellowing, or chlorosis, of the foliage. Chlorosis is a condition in which the grass blades produce insufficient chlorophyll resulting in the discoloration of the grass blades. The disease begins to appear within 24-36 hours after the grass has been infected with the disease and the first symptoms start out as small spots in the lawn. The grasses that are affected may start to wilt as the disease takes hold and starts to attack the grass. As the disease progresses, the small spots will rapidly grow and get bigger every day and these spots will take on a yellowish/brownish color with a slight orangish tint right around the edge of the patch. There is not a distinct pattern that the disease has; the patterns in the lawns can be circular or irregular shaped.

Brown patch usually just kills the blades of the grass and the crown and roots are not normally affected; this allows the chance for the grass to recover if properly managed. When the disease is present and the grass blades are affected, the diseased blades are easily separated at the base of the plant. As the disease progresses, the grass blades begin to die off resulting in the thinning of the grass which then opens the door for weeds to be present in the affected areas. In order to allow the grass to recover, a fungicide application will be needed and also a herbicide application may be needed if weeds have taken over the areas where brown batch has occurred.

The correct management of lawns during the summer months can greatly reduce the risk of brown patch showing up in your yard during the fall. It usually develops in areas where air flow is reduced or restricted, like around trees, shrubs, fences and other areas which delays the drying of the grass following a rain or irrigation of the lawn. Some of the best preventative methods during the summer are to aerate the ground often, reduce shade to affected area(s), and follow a fertilization schedule that is suited for your yard and needs. Also, following a proper watering/irrigation schedule can also help to decrease the chances of the disease showing up in lawns because added moisture late in the day will allow for the excessive moisture to be present while the temperature decreases in the evening resulting in ideal conditions for the disease to spread. Another helpful management practice that can be done to help reduce the risk of the disease is to reduce the thatch in the yard during the summer. Thatch is a dense layer of living and dead organic matter on the soil surface that primarily consists of turf grass stem and roots. This area can hold moisture and can act as an incubator for the fungus allowing for the disease to spread; therefore, reducing the amount of thatch can be very beneficial.

If brown patch is present in yards, it can be controlled. Once the disease is properly identified, proper treatment can begin. If fungicides are needed, they can limit any further damage that might occur if left untreated. The number of fungicide applications that will be needed, will depend on how long ideal conditions continue to be present. Here in Southwest Louisiana, we tend to have ideal conditions for a longer period of time compared to our neighbors in North Louisiana. How long it takes to go from summer to winter, and the frequency of rain, will determine how many applications are necessary. When using fungicides, always read the label and follow the recommended rate and application procedures. By mid- to late November and early December, most warm-season grasses are completely dormant or partially dormant so the risk of brown patch has drastically reduced; therefore, treatment may not be needed. It is important to carefully maintain lawns year around so that lawns have the ability to grow without any risk factors, like brown patch.

On another note, the Acadia Parish LSU AgCenter will be hosting a Fall Vegetable/Fruit Garden Seminar on Sept. 26, 2011. The seminar will take place at the LSU AgCenter Office which is located at 157 Cherokee Dr., Crowley, La., and it will be held from 9 a.m.-noon. A variety of topics will be covered by LSU AgCenter specialists and extension personnel. Topics will include: vegetable garden varieties, proper care of gardens during fall months, diseases that pose challenges in gardens and a special strawberry presentation that will cover planting and basic care of strawberry plants. The specialists and extension personnel will also be on hand to answer any questions or concerns that you may have about your garden.

For questions about brown patch or the upcoming Fall Vegetable/Fruit Garden Seminar please contact Jeremy Hebert at the Acadia Parish LSU AgCenter Office at 337-788-8821.

9/8/2011 6:43:51 PM
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