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Simplot Turf and Horticulture, West 5300 Riverbend Ave., Post Falls, ID 83854-9499
Corresponding author (dbrede{at}simplot.com)
‘Rugby II’ Kentucky bluegrass (Poa pratensis L.) (Reg. no. CV-58, PI 599223) is a turf-type cultivar released in August 1996 by Simplot Turf and Horticulture, Post Falls, ID. Rugby II was tested under the experimental designations 87-0018 and MED-18.
Rugby II originated as a single-plant selection from an apomictic Kentucky bluegrass found growing in a closely mowed cemetery in southern Washington State in July 1987. The selection traced its origin to when the cemetery was first seeded in the 1930s. The patch, 
7 m in diam., from which 87-0018 was selected, was dense and dark green, even though it was growing under substantial tree shade.
Vegetative propagules of this plant were transferred to the greenhouse and were later transplanted to the field in Post Falls as spaced plants in May 1988. Seed harvested from these plants was used to establish turf trials in 1989 and 1992, a replicated seed yield trial in August 1992, and a plant variety protection (PVP) trial in June 1994 near Post Falls.
Rugby II is not known to be genetically related to ‘Rugby’ (Beard, 1988), although it will be marketed for similar turf purposes. Rugby II is most similar in appearance to ‘Blacksburg’ (PI 601414) (Alderson and Sharp, 1994) and ‘Midnight’ (PI 601107) (Meyer et al, 1984); however, it can be differentiated from Blacksburg based on 21 botanical measures (as recorded in the U.S. PVP application of Rugby II, no. 9700383), including a longer panicle length, more branches at the lowest panicle node, and a narrower flag leaf width. Rugby II demonstrated significantly (P = 0.001) longer culm length than Blacksburg and Midnight in two years of field evaluations.
Progeny trials were conducted in spaced-plant nurseries established near Post Falls in May 1994 to determine the level of apomixis. Of 1678 Rugby II plants, 10.4% were variants in the vegetative (preheading) stage, 3.9% were heading maturity variants, 1% seedhead variants, 0.8% miniature plants, and 0.2% were headless plants. Many of these variants will not show up in commercial seed production because of the masking effect of dense stands. In spaced-plant nurseries, Rugby II averaged 85% apomictic but varied depending upon weather and year.
At anthesis, variants can be recognized by differences in seedhead color. On the whole, variants have an earlier, taller, and lighter green seedhead. Approximately 2% of Rugby II plants are shorter growing variants with later maturity. Approximately 3% of Rugby II plants (variants) have a "common-type" appearance, with culms averaging 86 cm in length. These plants have a light green color and susceptibility to rust (caused by Puccinia spp.) and leaf spot (caused by Drechslera spp.), above that of the majority. The common-type variants have a lacier, drooping seedhead, without the purplish tinge. Approximately 1% of the plants have a shorter growing seedhead and plant form, similar to ‘Limousine’ Kentucky bluegrass (Alderson and Sharp, 1994), averaging 54 cm in culm length. Aberrant progeny are rogued from seedstock fields to ensure continued uniformity and stability, but they will continue to occur in every generation.
Rugby II was tested in the National Turfgrass Evaluation Program (NTEP) trials for Kentucky bluegrass, established in 1995 (Morris, 1999), where it demonstrated improved drought tolerance (dormancy), and resistance to leafspot and melting out [caused by Drechslera poae (Baudys) Shoem], stripe smut [caused by Ustilago striiformis (Westend.) Niessl.], stem rust (caused by P. graminis Pers.:Pers.), necrotic ring spot (caused by Leptosphaeria korrae J. Walker and A.M. Smith), and summer patch (caused by Magnaporthe poae Landschoot and Jackson), and susceptibility to powdery mildew (caused by Erysiphe graminis DC. ex Merat).
In five years of commercial seed production, Rugby II has shown the potential for high yields of quality seed with freedom from ergot [caused by Claviceps purpurea (Fr.) Tul.] honeydew and sclerotia. Rugby II has exhibited no adverse reactions to labeled Kentucky bluegrass pesticides.
Rugby II is recommended for lawns, golf courses, parks, and sports turf in areas where Kentucky bluegrass is well adapted for turf. It can be grown in full sun or some shade. Rugby II is compatible in blends and mixtures with other cool-season turfgrasses.
Breeder seed, first harvested in 1995, is maintained by Simplot Turf and Horticulture. Seed propagation is limited to four cycles of increase: Breeder, Foundation, Registered, and Certified. U.S. Plant Variety Protection status for Rugby II has been applied for (PVP certificate no. 9700383).
NOTES
Accepted for publication September 30, 2000.
REFERENCES
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