Kentucky bluegrass blend ecology

Blending turfgrass varieties to combine desirable characteristics is a common management strategy, but determining the varietal composition of blended Kentucky bluegrass (Poa pratensis L.) stands has not been possible prior to the advent of molecular markers. This research was conducted to efficiently determine varietal composition of blended stands by DNA fingerprinting and study factors that may dictate the varietal composition of blended turf.; Three DNA extraction methods were compared for cost, efficiency, and reproducibility along with comparisons between laboratory investigators. In a second group of experiments the composition of several blended stands was determined. Genetic markers were used to determine the varietal composition on two golf courses and in replicated plots containing blends of ‘Blacksburg’, ‘Midnight’, and ‘Unique’ Kentucky bluegrass. Spatial patterns were identified using indices of dispersion and the number of samples required to characterize blends was estimated. Lastly, relationships between disease severity, seed characteristics and percentage of varieties were quantified.; Of the three DNA extraction methods compared, the DNAzol® reagent method was an affordable and efficient procedure. The PEX/CTAB method was the least expensive, but extracted the lowest amount of quality DNA. The DNeasy™ kit extracted the most high quality DNA, but at a greater cost. Spending more time with the DNA extraction procedures led to more DNA isloated.; Independent of management, location, time of seeding, or the intended varietal composition, blends of ‘Blacksburg’, ‘Midnight’, and ‘Unique’ Kentucky bluegrass had similar compositions. Aggressiveness or competitive ability, not environment or management, may dictate the prevalence of a variety in a blend. The varieties were distributed randomly along transects on the golf courses.; Seed size and germination differed between varieties and seedlots within varieties. Blending seed using seed weight resulted in an actual composition similar to the intended composition. Including a susceptible variety in a blend resulted in more severe rust and powdery mildew than when not included. Likewise, including resistant varieties as a large percentage of a blend reduced rust and powdery mildew severity.