There are over 100 diseases that affect North Carolina turfgrasses, but fortunately, there are only about 18 turfgrass diseases that develop year after year. Most diseases are caused by fungi, although grass species vary to their susceptibility to certain diseases. There are other factors that affect disease development such as lawn health, geographical area, weather and seasonal conditions as well as lawn maintenance practices. Here are a few diseases that you may encounter.
Brown Patch – Rhizoctonia Solani – most severe during extended periods of hot, humid weather, Brown Patch is a fungal disease that can begin to develop between May and September. The disease symptoms vary depending on the turfgrass but for the most part, the first symptoms are water-soaked areas on leaf blades that soon dry, wither and turn light brown. On most lawns, where the grass is cut high, the disease appears as roughly circular patches that are brown, tan, or yellow in color and range from 6” to several feet in diameter. In close cut turfgrasses, brown patch develops as roughly circular patches ranging from a few inches to several feet in diameter that are brown or orange in color.
Brown patch is most severe during hot and humid weather. Turfgrass leaves must be continuously wet for at least 10 to 12 hours for the fungus to infect. Poor soil drainage, lack of air movement, shade, cloudy weather, dew, over-watering, and watering in the afternoon all favor prolonged leaf wetness and increased disease severity.
Contact Nature’s Select if you suspect brown patch in your turfgrass. Fungicides are effective for brown patch control and can be applied on a preventative or curative basis. Treatment is necessary to stop the fungi from spreading to healthy parts of your turfgrass. Consider a preventive fungicide program for tall fescue when conditions favor disease development. For best results, preventative applications should be initiated in the late spring or early summer when night temperatures consistently exceed 60F.
Gray Leaf Spot – Pyricularia Grisea – initially appears as spots on leaves that are round or oval and tan in color with a dark brown border. When the leaves are wet or humidity is high, the leaf spots turn gray and fuzzy. In time, the leaf spots expand and cause the leaf to die back from the tip. In tall fescues, foliar blighting initially occurs in patches from 6 to 12 inches in diameter that are orange to yellow in color.
If turfgrass is infected, symptoms usually appear during July, August & September. Preventative fungicide applications are and should be initiated in mid-June to early-July. Tall fescue should be monitored frequently so that fungicides can be applied to stop epidemic development.
Red Thread – Laetisaria Fuciformis – usually thrives in temperatures between 40oF to 85oF and in locations that are low in nitrogen. It also occurs in areas that experience more than 10 hours a day of foliar wetness for several consecutive days.
Red thread develops in circular or irregular patches from 4 inches to 2 feet in diameter. The affected leaves within the patches are usually tan or bleached white in color but from a distance seem like they’re red because of red strands of fungal growth that come from the leaves. After prolonged periods of disease development, the patches may merge together to make large irregular shapes areas of damaged turf. In most cases, no treatment is needed. Turfgrasses affected by Red Thread are Kentucky bluegrass, tall fescue, fine fescue and perennial ryegrass. Symptoms can be seen during the months of March to June and September to December.
Pythium Blight – Pythium Aphanidermatum – usually appears during hot, humid weather and is most common in the wettest areas of turf and in the surface of drainage pattern. The disease causes greasy, brown circular spots that start out about ¾ to 2 inches in diameter but quickly enlarge in size. The leaves within the patches are matted, orange or dark gray in color.
Turfgrasses affected by this disease are bentgrass, bluegrasses, fescues and ryegrasses. This disease favors night temperatures over 68oF and occurs in areas that experience more than 10 hours a day of foliar wetness for several consecutive days.
It may not sound like it but drought is dangerous for any landscapes because it is drought-stressed lawns are most susceptible to damage from disease and insects. Grass change from bright green to a dull gray or blue green is an early sign of drought stress. When your footprints don’t spring back after you walk across the lawn is another indicator to drought stress. As the effects progress, the turf loses its green color and turns yellow then tan.
Mowing may seem like a fool-proof job but properly mowed lawns are actually healthier. Avoid “scalping” your grass. Scalping is letting our grass grow tall and then removing more than 1/3 of the leaf blade. Mowing the lawn too low can also cause damage.
Be sure to sharpen your lawn mower blades because dull blades can shred grass and cause discoloration at the tips. It is recommended to sharpen blades several times each growing season.
Raise the mower height a little bit when your lawn is recovering from drought, insect damage or disease. It is also important to avoid cutting your grass when it is wet which can cause brown spots from clippings clumping together and smothering your lawn.
The ideal frequency for cutting your lawn is dependent on the growth of your grass. It is recommended not to cut more than a 1/3 of the grass blade in one mowing.
Be sure to moisten the top 3 to 4 inches of soil which covers the root zone. For established lawns, they should be watered deeply about once a week to encourage deeper root growth. On average, most grasses need about an inch of water each week.
It is also suggested to do your watering in the morning hours so the leaves can dry off a bit before the hot sun hits them. Evening hours is sometimes acceptable if the temperatures are warm enough to insure foliage drying out before the temperature starts to drop overnight. Wet leaves and foliage makes them more susceptible to fungus and diseases. Water the lawn once the grass begins to discolor and wilt. Once your lawn had turned brown and lost all color during the drought, it will take several weeks of steady watering to spur re-growth.
AERATION & SEEDING
One of the most important things you can do for your lawn in the Fall is to Aerate and Seed. The heavily compacted clay soils of the Piedmont restrict the water and air content of the soil, which are very important to plant and grass growth and health.
Aerating, removing cores of soil, helps break up the compacted soil, providing oxygen for the roots and helps develop rich topsoil. Your grass will have greater nutrient uptake giving you better and deeper root growth. The average life cycle of fescue is about 3 years and every year, the normal fescue lawn loses about 1/3 of grass; it only makes sense to replace it.
Contact Nature’s Select for your next Aeration and Seeding.