How Bermuda Recovers from Spring Dead Spot

How Bermuda Recovers from Spring Dead Spot

Ophiospherella spp. Distribution in the mid-Atlantic. Species were identified using real-time PCR, and regions were color coded: Red=VA Mountains; Blue = Virginia Piedmont; Orange = Virginia Coastal Plain; Green = DE, MD, and NC. (Photo courtesy of Wendell Hutchins)

Hybrid Bermuda grass (Cynodon dactylon × C. transvaalensis) is one of the most desirable grasses for golf courses in the transition zone due to its aggressive growth habit, traffic tolerance, uniformity, and color (5,7).

Spring dead spot (SDS) caused by Ophiospherella spp.It is one of the most dangerous diseases that affect Bermuda plants.Cynodon spp.) It grows in areas where winter dormancy occurs. Spring dead spot is widespread throughout the United States, with 24 states reporting the disease (5, 6).

As the name suggests, symptoms of SDS first appear in the spring when bermudagrass begins to turn green. The circular spots or rings of grass remain dormant and eventually die. Dead spot in the spring does not directly kill bermudagrass, but fungi can attack the roots, roots, and stagnation in the fall, increasing susceptibility to cold and freeze injury during the winter (2, 7, 8, 9).

O. herpotricha And Hey Koray They are the two predominant species causing SDS in the mid-Atlantic region of the United States (5, 6). Ophiospherella spp. It is found within the three geographic regions of Virginia and surrounding states (Figure 1).

Sites west of Charlottesville (78.5°W) have more O. herpotricha of locations east of this meridian, while the eastern regions have a greater number Hey Koray (5). Furthermore it, O. herpotricha And Hey Koray The frequency of occurrence can also be affected by the variety (6). Given the geographic diversity of the species, we recommend submitting SDS samples to a diagnostic clinic for accurate identification.

Spring dead spot is a challenge that must be managed in Virginia. Most SDS research efforts recommend using preventive practices such as fungicide applications and other cultural practices in the fall. We often overlook damage recovery strategies in the spring and early summer.

Previous research at Virginia Tech evaluated shearing for recovery and long-term suppression of SDS (7). Mowing removes most surface plant material and thatch, providing a smoother playing surface.

Mowing was conducted on May 29, 2015 at depths of 0.16 and 0.32 inches. Granular broadcast applications for urea and ammonium sulfate (0.5 lb. N per 1,000 ft2) follows the start of the trial and every seven days thereafter for six weeks. Visual and reflectance data show that split mowing treatments resulted in higher turf quality, and plots treated with ammonium sulfate recovered faster than plots treated with urea, regardless of depth (7).

Main effect of fertility on bermudagrass recovery area under the progress curve (AUPC).  Means are compared across years and colored bars represent different fertility practices.  Bars in the same year with distinct letters are significantly different (P = 0.05).  (Graphic: Golfdome Crew)

Main effect of fertility on bermudagrass recovery area under the progress curve (AUPC). Averages are compared across years, and colored bars represent different fertility practices. Bars in the same year with distinct letters are significantly different (P = 0.05). (Graphic: Golfdome Crew)

Farming practices

Our goal was to evaluate other cultivation practices for their effect on bermudagrass recovery from SDS. We conducted a field trial from May 30 to August 12, 2019, and repeated from June 25 to August 6, 2020, on NorthBridge Bermudagrass in Blacksburg, Virginia. There were six treatments in the study:

  • Untreated control
  • Two applications of urea two weeks apart, for a total of 2 lbs. n per 1000 feet2
  • Verticutting
  • Checking hard clay
  • Verticutting plus two applications of urea two weeks apart, for a total of 2 lbs. n per 1000 feet2And
  • Solid aeration plus two applications of urea two weeks apart, for a total of 2 lbs. n per 1000 feet2

We evaluated plots for percent SDS throughout the study period. Data were analyzed as percentage change of SDS compared to
A preliminary evaluation to measure bermudagrass recovery from SDS. The data were then converted to area under the progress curve (AUPC) to include bermudagrass recovery over time.

The main effect of fertility increased bermudagrass recovery by 19 percent in 2019 and 33 percent in 2020 compared to unfertilized plots (Figure 2). However, the main effects of hard aeration and vertical cutting prevented bermudagrass recovery in 2020 by more than 32 percent compared to uncropped land (Figure 3). There was no effect of cultivation on bermudagrass recovery in 2019.

Main impact of agriculture on bermudagrass recovery area under the progress curve (AUPC).  Means are compared across years and colored bars represent different agricultural practices.  Bars in the same year with distinct letters are significantly different (P = 0.05).  *NS is not significant.  (Graphic: Golfdome Crew)

Main impact of agriculture on bermudagrass recovery area under the progress curve (AUPC). Averages are compared across years, and colored bars represent different agricultural practices. Bars in the same year with distinct letters are significantly different (P = 0.05). *NS is not significant. (Graphic: Golfdome Crew)

This field trial indicates that urea applications in late spring or early summer are sufficient to improve bermudagrass recovery from SDS damage. In contrast, cultivation practices such as vertical cutting and hard aeration early in the growing season, especially without fertility, can prevent bermudagrass recovery from SDS damage. The result is surprising because general recommendations for improving SDS recovery include cultivation practices (4, 7).

Over the past 30 years, research results strongly recommend spring nitrogen applications to enhance SDS recovery (2, 3, 4) and are consistent with previous mowing experiments (7). An old trial in Maryland evaluated several different sources of nitrogen with potassium chloride (2, 3). All nitrogen treatments helped speed recovery from SDS in the first year.

Fertilizer containing ammonia (NH4-N) reduced the incidence of SDS in the second and third years of the experiment. Soil pH data indicate that soil acidification by ammonia nitrogen helped reduce the severity of SDS over time.

Our recommendation is to fertilize with 2 lbs. n per 1000 feet2 In the spring if your Bermuda plant is suffering from SDS damage. We also recommend delaying traditional farming practices such as vertical farming and aeration until damaged areas recover. Future research will focus on other planting methods and the effect of different fertilizer types on bermudagrass recovery from SDS.

Research takeaways

  • Ophiospherella herbotrichia And Hey Koray They are the two dominant species that cause SDS in the mid-Atlantic region of the United States
  • Two spring applications of urea (total 2 lbs N per 1,000 ft.).2) Enhance recovery of NorthBridge hybrid bermudagrass from spring dead spot (SDS) in the first year.
  • Rigid aeration and vertical cutting did not improve SDS recovery in the spring.

Wendell Hutchins, Ph.D. is a graduate student at Virginia Tech and can be reached at wendelljh@vt.edu. Mike Gotley, Ph.D., and David McCall, Ph.D., are faculty members at Virginia Tech.

The full peer-reviewed article of this work can be found at Hortscience https://doi.org/10.21273/HORTSCI16235-21

References

  1. Beck, L.L.; Cooper, T.; Hefner, A. J.; Straw, cm; Henery, GM 2013. Effect of pre-emergence herbicides on bermudagrass recovery from SDS. Golf course management. July. 81(7): p. 80-85. https://archive.lib.msu.edu/tic/gcman/article/2013jul80.pdf
  2. Dernwydden, Peter H. 1991. Reducing the risk of dead spots in spring. Golf course management. He walks. 59(3):68,70,72,74,80. https://archive.lib.msu.edu/tic/gcman/article/1991mar68.pdf
  3. Dernwydden, PH; Krahay, J.N.; Davis, D. B. 1991. Spring dead spot and bermudagrass quality as affected by nitrogen and potassium source. Crop science. 31:1674-1680.
  4. Dowling, Elliot L. 2017. Spring's Dead Spot. USGA Regional Update. May 5, 2017. 2 p. https://tic.msu.edu/tgif/urltab?RECNO=312972
  5. Hutchens, W.J., Henderson, CA, Bush, E., & McCall, D.S. 2019. Geographic distribution of spring deadspot species in the mid-Atlantic (abstract). ASA, CSSA, and SSSA International Annual Meetings (2019), San Antonio, TX. https://scisoc.confex.com/scisoc/2019am/meetingapp.cgi/Paper/120049
  6. Hutchins, W. J., Henderson, C. A., Bush, E. A., Cairns, J. B., & McCall, D. S. 2021b. Geographic distribution of Ophiospherella Species in the Mid-Atlantic United States. Plant health programme. https://doi.org/10.1094/PHP-04-21-0076-S
  7. Shelton, CD; McCall, D.S.; Miller, GL 2016. Effect of mowing on bermudagrass dead spots in spring. Proceedings of the first annual meeting of the Northeast Plant, Pest, and Soil Conference. s. 44. http://www.newss.org/proceedings/Proceedings_NEPPSC16_Vol1.pdf#page=70
  8. Tommaso Peterson, Maria. 2009. Effectiveness of spring fungicide applications plus organic fertilizers to control spring dead spot of bermudagrass. 2009 USGA Turf and Environment Research Digest. p. 11. http://archive.lib.msu.edu/tic/ressum/2009/11.pdf
  9. Walker, NR, Mitchell, TK, Morton, AN, and Marek, SM 2006. Effect of temperature and time of year on the colonization of bermudagrass roots by Ophiosphaerella Herpotricha. dis plant. 90:1326-1330. https://doi.org/10.1094/PD-90-1326

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