Annual bluegrass (Poa annua L.; ABG) is one of the most widely distributed turfgrass species in the world and is generally considered a weed on golf course putting greens. Variation in ABG populations exists and is dependent upon a large number of factors. Due to this natural variation, control of the various biotypes can be highly variable. The objective of this study was to investigate the tolerance of perennial ABG biotypes to methiozolin, amicarbazone and bispyribac-sodium.  Greenhouse studies were conducted in 2011.  A total of 30 ABG biotypes were seeded at a rate of 98 kg seed/ha into pots measuring 79.2 cm² on 3 May and 16 September. Pots were arranged in a randomized complete block design with five replications.  Prior to treatment, ABG was fertilized and treated with fungicides to prevent diseases. Herbicide treatments included amicarbazone (0.147 kg a.i./ha), bispyribac-sodium (0.074 kg a.i./ha), methiozolin (2.0 kg a.i/ha), and an untreated control.  All treatments were applied twice on a 14-day interval in 815 L H₂0/ha using a CO₂ backpack sprayer (276 kPa). The ABG pots treated with amicarbazone were severely injured within 1 week of initial application. Turfgrass treated with bispyribac-sodium or methiozolin resulted in a less rapid decline when compared to amicarbazone. In general, all 30 ABG biotypes were killed within 3 and 6 weeks when treated with amicarbazone and methiozolin, respectively. At the conclusion of the study, control of ABG was highly variable in pots treated with bispyribac-sodium.  Based on the initial trial, amicarbazone and methiozolin provided complete control of all 30 ABG biotypes evaluated in this study. Amicarbazone appears to be most useful in situations of minimal ABG population and/or where a rapid kill is desired. Methiozolin provided a slower suppression of ABG and may be useful in situations where high populations are present or limited disruption to the putting surface is desired. The study is current being repeated and results of the completed study will be discussed.