Research Articles continued
Dormant Seeding of Zoysiagrass Virginia Tech Researchers: Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist and Professor; Whitnee Askew, Research Technician; and Eric Reasor, Undergraduate Student, Crop & Soil Environmental Sciences Dept. Research Sponsors: Patten Seed and Seed Research of Oregon
One
of the biggest challenges facing the use of seeded zoysiagrasses as a low-input, high-density turfgrass is its very slow establishment rate. Research at the University of Arkansas, published in 2006, demonstrated the potential for dormant seeding of bermudagrass. Could the same principle apply to seeded zoysiagrasses?
Our research
Each month from February 2011 through June 2011, we applied the seeds of two cultivars of zoysiagrass (‘Compadre’ and ‘Zenith’) at two seeding rates (1 and 2 lbs. of pure live seed per 1,000 ft2) on research plots at the Turfgrass Research Center. The existing stand of cool-season grass (perennial ryegrass) in the plots was treated 1 to 2 weeks prior to each monthly seeding date with glyphosate at 3 lbs. ai/A, and the plots were scarified with a power rake prior to seeding. Weed control treatments of 0.013 lb. ai/A foramsulfuron + 0.25 lb. ai/A quinclorac (primarily for intense pressure from crabgrass and goosegrass) were applied on June 24, July 9, July 20 and August 5. The plots received 1 lb. of N/1,000 ft2 (19-19-19) on July 1. Two times a week during periods of active growth, the plots were mowed to 1-1/2" with a rotary mower. No supplemental irrigation was applied. Germination (across all cultivars and seeding rates) was observed on April 26 for Feb. seeded plots, on May 30 for March seedings, on June 6 for April seedings, on June 16 for May seedings, and July 12 for June seedings.
Preliminary results
• There were no consistent statistical differences in germination or establishment rates between cultivars or seeding rates. Obvious differences in % zoysiagrass cover between seeding dates was observed (see photo and Table 1). Glyphosate control of existing coolseason grass was poor in March-treated plots and likely contributed to reduced stand establishment compared to February and April seedings. • “Dormant seedings” are demonstrating early establishment success compared to traditional timing approaches under minimal input (zero to low irrigation and fertility), but regularly scheduled weed control is critical for success. c
Zoysiagrass coverage on September 13, 2001, as indicated in plots marked by seeding month, variety (C = ‘Compadre’, Z = ‘Zenith’) and seeding rate (1 or 2 lbs. of pure live seed per 1,000 ft2).
Table 1. Visual estimations of % zoysiagrass in varying monthly seeding establishments of ‘Compadre’ and ‘Zenith’ cultivars of zoysiagrass.
Zoysiagrass Coverage Seeding Month
July 1
July 18
Aug. 2
Aug. 30
Sept. 13
Oct. 12
February
28.1% a
37.2% b
54.1% a
68.4% b
76.9% b
76.6% b
March
22.2% b
30.2% c
44.1% b
62.8% b
74.1% b
75.6% bc
April
30.6% a
47.2% a
61.3% a
83.1% a
91.6% a
91.0% a
May
9.4% c
21.7% d
33.1% c
57.5% b
67.2% b
67.2% c
June
0.0% d
1.5% e
4.2% d
12.6% c
17.3% c
16.6% d
Means followed by the same letter are not significantly different according to Student’s t-test at a p value of 0.05. 14 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org