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Spring Seeding Tall Fescue

March 21, 2008
By Grady Miller, Fred Yelverton, Travis Gannon, Charles Peacock and Matt Martin

The drought conditions of summer and fall of 2007 caused considerable damage to many lawns. Normally, fall is the best time for renovation and seeding of cool-season lawns. However, due to the prolonged drought conditions many elected to delay fall seeding. In addition, those that seeded in the fall as normal had less success than most years. As a result, many landscape managers and property owners have expressed interest in spring seeding of tall fescue.

For those that are considering spring seeding, some considerations need to be made before proceeding. Because spring seeding carries additional risk far beyond fall seeding, NCSU recommendations have not previously included provisions for spring seeding. Spring-established tall fescue is more susceptible to drought, heat, fungal diseases, and weed encroachment. With normal summer weather patterns, spring seeding is not likely to result in a year-long stand of healthy tall fescue. As a result, those who elect to seed tall fescue in the spring should also plan and budget for additional seeding this fall.

Several areas of the state are under mandatory water restrictions, and at least a few municipalities have eliminated outdoor watering. While this further reduces the assurance of success for spring establishment, most of the lawns in North Carolina were established and have been maintained without any in-ground irrigation system.

Optimum air temperatures for tall fescue germination are 68 to 77°F and soil temperatures greater than 60°F. If tall fescue is seeded at less than ideal conditions (too cool or no soil moisture), the seed will stay viable in the spring until the temperatures warm and soil moisture is available. Seeding at less optimum time may result in reduced fill which may increase weed germination. But with the need for both moisture and moderate temperatures, it is better to seed a little early in anticipation of spring rainfall. Based on air and soil temperatures seeding between mid-February and late March is probably the best time for North Carolina. Planting later will greatly reduce tall fescue survival through the summer.

It is best to choose cultivars from the turffiles website (http://www.turffiles.ncsu.edu). If you buy a tall fescue blend, try to find one with at least one of the cultivars from the list of recommended cultivars. These grasses were chosen because they produce a high quality turf in North Carolina and have been shown to be less susceptible to brown patch. It is not recommended that Kentucky bluegrass be included in the seed mixture due to the slow germination and establishment rate of bluegrass. A typical seeding rate is 5 to 6 pounds of seed per 1000 square feet. Germination will normally be in 10 to 21 days with soil moisture and suitable soil temperatures.

Before seeding core aerification is recommended to reduce compacted areas. This will increase the chance of water getting into the soil and reduce runoff. Slit seeding is recommended over broadcast seeding. Getting good soil to seed contact is paramount to maximize available soil moisture. Core aerification followed by overseeding would be the second best option. The core aerification holes will capture seed and hold moisture so the tall fescue seedlings often come up as a tuft of turf from the aerification holes.

Follow normal tall fescue fertilization practices as outlined in Carolina Lawns. The suggested yearly application is 0.5 to 1.0 pounds of nitrogen fertilizer per 1000 square feet 2 to 3 times per year. A typical spring application of nitrogen fertilizer will be 0.5 to 1.0 pounds of nitrogen in February or March with the remainder of the fertilizer applied in the fall. Include phosphorus and potassium fertilizers if soil tests indicate there is a need. In the absence of a soil test, a 16-4-8 or similar N-P-K ratio fertilizer may be used this spring. Before additional fertilizer or lime is added, conduct a soil test (http://www.ncagr.com/agronomi/sthome.htm).

If irrigation is available, set your controller within current water restrictions for your area. Irrigate early in the morning to reduce water loss due to evaporation. In the early spring, ¼ to ½ inch water per week of water (via rainfall or irrigation) is generally sufficient to meet the turf's water needs. To dial in your irrigation settings based on turfgrass needs for your location, use the TIMS website available at http://www.turffiles.ncsu.edu/tims.

Since seeds and seedlings may be damaged by some herbicide applications, spring seeded tall fescue requires some changes from a typical pre-emergence herbicide program. In addition post-emergence programs must also be altered for both broadleaf and grass control. Make sure fescue is extensively tillered prior to applying any 3-way herbicides or pre-emergence products. Some products that may be used on spring-seeded lawns include: Tupersan, Dimension, Acclaim Extra, Drive, Tenacity, Prodiamine, and Pendimehalin.

Several weed control scenarios could be used. One scenario for spring seeding would involve using no herbicide at seeding. Once the new plantings have tillered and have been mowed at least twice, a postemergence herbicide such as Drive or Acclaim Extra could be applied in combination with a preemergence herbicide. Another scenario would include using Tupersan at seeding of tall fescue. This herbicide will provide 30 days or so of preemergence activity. Once the seedlings have tillered, the normal preemergence herbicide could be applied. It should also be mentioned that Dimension has some early postemergence crabgrass activity. Typically, Dimension will kill crabgrass that has emerged but pre-tiller. For more specific weed control strategies, check turffiles (http://www.turffiles.ncsu.edu).

It is very important that tall fescue be maintained at the proper mowing height to minimize crabgrass incidence. Studies have shown that a 3" mowing height minimizes crabgrass emergence but is still not so tall to dramatically increase disease problems.

Fungal diseases are a large part of the reason why spring seeding of tall fescue is not recommended. Young, immature turfgrass plants are more susceptible to diseases such as damping off, brown patch, gray leaf spot, and Pythium blight. Fall-seeded tall fescue is given more time to reach maturity before these diseases become active in the spring and summer months. To minimize the risk of damage to spring-seedings from these diseases, closely follow the soil preparation, seeding, and establishment guidelines above to speed turf emergence and maturation. Once established, minimize nitrogen levels during the summer months and mow regularly to keep the canopy open and dry. If water is available, irrigation should be applied on a deep and infrequent basis, so that the soil is not constantly saturated. For assistance with irrigation scheduling, use the TIMS website to track water requirements in your area. Irrigation cycles should be scheduled for the early morning hours, before sunrise, to minimize periods of leaf wetness.

Fungicide applications will help to increase the success of spring seedings. However, because fungal diseases kill turfgrass seedlings rapidly, preventative or early curative applications are essential. Damping-off can be prevented with a single application of azoxystrobin (Heritage) or mefanoxam (Subdue Maxx) at the time of seedling emergence. Brown patch becomes active in the late spring or early summer when night temperatures are consistently above 60°F, thus preventative fungicide applications should be initiated at this time. All of the fungicides labeled for brown patch will control the disease effectively, but they differ drastically in application interval. Products containing the active ingredients azoxystrobin (Heritage), fluoxastrobin (Disarm), pyraclostrobin (Insignia), or trifloxystrobin (Compass) can provide 21 to 30 days of brown patch suppression.

During June, July, and August, spring-seeded tall fescue should be monitored frequently for symptoms of gray leaf spot and Pythium blight so that fungicides can be applied before unacceptable damage occurs. Of the fungicides recommended above for brown patch control, Heritage, Insignia, and Disarm also provide good control of both gray leaf spot and Pythium blight. However, increased application rates and frequencies are generally needed to provide acceptable control of these diseases.

For more detailed information on diagnosis and management of tall fescue diseases, refer to the Turfgrass Disease Information Notes (http://www.ces.ncsu.edu/depts/pp/notes/Turfgrass/turfgrass_contents.html) from the Department of Plant Pathology at NC State. Disease diagnosis services are also available through the Plant Disease and Insect Clinic. For information and sample submission instructions, visit their website at www.ncsu.edu/pdic.

Unfortunately, spring seeded lawns will likely still require fall seeding (renovation) since spring-established plants are more susceptible to drought plus heat and disease severity. So, if spring seeding tall fescue, also budget for fall renovation.

If you have given up on tall fescue and want more information on other grasses, the Turffiles Web site contains information on different types of grasses and which are best suited for different applications and parts of North Carolina.

Managing Spring Seeded Grasses, Grady Miller

Weed Management Strategies for Newly Seeded Lawns, Fred Yelverton

Weed Management Strategies for Newly/Spring Seeded Lawns, Travis Gannon

Spring Seeding of Cool-Season Grasses: Disease Considerations, Lane Tredway