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Simplot/Jacklin Seed, West 5300 Riverbend Ave., Post Falls, ID 83854-9499
* Corresponding author (doug.brede{at}simplot.com)
‘Chicago II’ Kentucky bluegrass (Poa pratensis L.) (Reg. no. CV-78, PI 615085) is a turf-type cultivar released in January 2000 by J.R. Simplot Co., Jacklin Seed, Post Falls, ID. Experimental designations for Chicago II were 93-2909 and J-2909.
Chicago II originated from an apomictic, single-plant selection from hybrid 91-0195, made in the field at Post Falls in July 1991 using ‘Limousine’ (Alderson and Sharp, 1994) to pollinate plants of ‘Midnight’ (Meyer et al., 1984). Seeds harvested from Midnight plants were individually sown into cells of greenhouse flats during the spring of 1992 and later transplanted to a spaced-plant nursery of 33500 plants. Offspring with characteristics dissimilar to Midnight were selected during maturation in the spring of 1993. Plant 93-2909 differed from Midnight for turf characteristics before seedhead expression. It produced 27 g of seed, nearly twice that for a typical Kentucky bluegrass spaced plant in northern Idaho. Seed harvested from this plant was used to establish a turf trial in 1993 and a seed yield trial in 1996. No other cultivars have been released from the 91-0195 hybridization; however, ‘Explorer’ (Brede, 2003b), ‘Arcadia’ (Brede, 2003a) and ‘Chicago’ (Brede, 2002) were progeny of an earlier Midnight/Limousine cross.
Progeny trials were conducted in 1996 to determine the level of apomixis. A survey of 1233 plants of Chicago II showed that 6.9% of plants were variants in the vegetative (pre-flowering) stage, 0.2% were heading maturity variants, 0.1% seedhead variants, and 1% were miniature plants. Approximately half of the variants were slightly taller plants with similar seedhead appearance. Many of these variants are indistinguishable from the majority plant form in normal row-planted seed production. The mean spaced-plant apomixis rate of Chicago II was 92%, but it varied from 90% to 95% or greater, depending on growing conditions.
In seed production, Chicago II is medium-late maturing and low growing with short culm and panicle length. In seed production, Chicago II plants grow strongly via rhizomes, with lateral one-year expansion of approximately 50 cm from a single spaced plant. Chicago II is unique from many bluegrasses in its relatively late emergence from the ground in the spring in seed fields. This delayed emergence does not manifest itself in mowed turf, where the cultivar maintains an attractive winter color and greens up moderately early in the spring.
Chicago II is noteworthy for its rich, dark green genetic color in mowed turf. It was darker green than 167 of the 173 entries in the 2000 National Turfgrass Evaluation Program (NTEP) trials for Kentucky bluegrass (Morris, 2003). It has good resistance to leafspot [caused by Drechslera poae (Baudys) Shoem] and moderate to good levels of resistance to stem rust (caused by Puccinia graminis Pers.:Pers.), summer patch (caused by Magnaporthe poae Landschoot and Jackson), Microdochium patch {caused by Microdochium nivale (Fr.) Samuels and Hallett [teleomorph: Monographella nivalis (Schaf) E. Muller]}, and brown patch (caused by Rhizoctonia solani Kühn) (Morris, 2002, 2003). In 4 yr of commercial seed production, Chicago II has demonstrated the potential for high yields of quality seed, relative freedom from ergot [caused by Claviceps purpurea (Fr.) Tul.], and no adverse reactions to labeled Kentucky bluegrass pesticides.
Chicago II is recommended for golf course tees, fairways, and roughs, and for lawns, parks, and sports turf, in full sun or some shade, in areas where Kentucky bluegrass is well adapted for turf. It is compatible in blends and mixtures with other cool-season turfgrasses at mowing heights as low as 13 mm.
Breeder seed, first harvested in 1996, is maintained by J.R. Simplot Co., Jacklin Seed. Seed propagation is limited to one generation each of Foundation, Registered, and Certified seed. U.S. Plant Variety Protection application no. 200100042 has been filed for Chicago II.
NOTES
Accepted for publication April 30, 2004.
REFERENCES
This article has been cited by other articles:
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  A.D. Brede Registration of 'Beyond' Kentucky Bluegrass Crop Sci., November 1, 2004; 44(6): 2267 - 2267. [Full Text] [PDF]
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