Patch Diseases

Common Patch Diseases:
Summer PatchNecrotic Ring SpotBrown PatchDollar Spot

Summer Patch

Necrotic Ring Spot

Brown Patch

 Dollar Spot


Patch Diseases

 Despite the different names, patch diseases have essentially similar symptoms. As the names suggest, symptoms of necrotic ring spot and patch disease include rings and circular patches of dead or dying turfgrass. Sometimes there is a center of relatively healthy grass in the center (frog eye) of the patch. In addition, weeds or non-susceptible turfgrass species may colonize the centers of patches where the diseased turfgrass has died. Both diseases are most severe on Kentucky bluegrass lawns that were seeded or sodded two to four years previously. Symptoms often become obvious in warm to hot, dry weather when the lawn becomes stressed. Areas along driveways, walls, sidewalks and other places that are heat-stressed or water-stressed will often show symptoms first.

When the disease first begins, rings or patches of blue-green wilting turfgrass will develop in the heat of the day. With time, the patches may grow together, obscuring the circular pattern of the damage. In lawns containing mixed turfgrass species, symptoms are not as distinct, but circular patterns of diseased turfgrass are generally present. Both diseases are caused by root-infecting fungi. Above-ground symptoms may be confused with other diseases such as brown patch disease. However, the roots and crowns of plants with necrotic ring spot or summer patch will be brown to black and rotted.

The fungi produces very similar dark brown, microscopic threadlike filaments that are found along the roots, crowns, and rhizomes of turf-grass. In both diseases, infection occurs before symptoms appear. The fungi spread from plant to plant and travel longer distances when feet and mowers spread spores, soil or infected plant parts.

Severe damage is most common on sodded Kentucky bluegrass lawns that have been planted on poorly prepared sites with poor drainage and compacted soil. It is important to properly prepare a lawn site with well-drained topsoil, correct pH, and balanced fertility. When possible, plant Kentucky bluegrass cultivars with resistance to these diseases or consider using sod with perennial ryegrass in the mix. This will help mask areas of infection. Similarly, overseeding with resistant cultivars and perennial ryegrass will improve already damaged areas. Once an area has been seeded or sodded, avoid stressful growing conditions.

There are also simple preventative measures you can take to lessen the severity of the disease. You should water deeply without causing moisture stress. Avoid early evening watering. Mow frequently to the recommended mowing height. It would be a good idea to fertilize to maintain appropriate nutrient levels and aerate to relieve compacted soils. A double aeration at right angles every spring and fall will reduce thatch layer and stimulate a deeper, healthier root system.

Lawn King, LLC performs turf disease scouting when we perform each fertilizer application. If there is a problem, we will inform you as to the type of disease, the severity and if treatment is required. Of course, as a team, (you and I) if you notice a problem, you should contact us immediately.



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E-mail :  mike@lawnkingllc.com