76-17 Evaluation of Triazine-Resistant and Susceptible Annual Bluegrass Biotypes Following Applications of Amicarbazone and Atrazine.

Poster Number 223

See more from this Division: C05 Turfgrass Science
See more from this Session: Graduate Student Poster Competition: Breeding, Physiology and Stress Management
Monday, November 1, 2010
Long Beach Convention Center, Exhibit Hall BC, Lower Level
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Daniel Perry, J. Scott McElroy, E. van Santen and Robert Walker, Auburn University, Auburn, AL
Annual bluegrass (Poa annua L.) is a ubiquitous, cool-season grass species that is challenging to control in fine turf.  Herbicide-resistant annual bluegrass has been reported across multiple states and countries. Many of these reports are attributed to herbicides with a photosystem II (PSII) inhibiting mode of action. Amicarbazone is a new photosystem II inhibitor being evaluated for annual bluegrass control, and the potential for resistance is a concern. Two greenhouse studies investigated the effects of amicarbazone on two triazine-resistant and two triazine-susceptible annual bluegrass biotypes. Herbicide treatments included amicarbazone (0.26 kg/ha), atrazine (1.7 kg/ha), and simazine (1.7 kg/ha). A nontreated was included for statistical comparison. Photosynthetic yield (ΦPSII) was measured 0, 1, 2, 4, 8, 16, 24, 48, 72, and 168 hours after application (HAA) using a pulse-modulated chlorophyll fluorometer. Plants were placed in artificial lighting 30 minutes prior to and during each measurement and placed in greenhouse growing conditions otherwise. Treatments were a factorial combination of herbicide treatment and annual bluegrass population. A significant herbicide by biotype interaction existed. Amicarbazone did not reduce ΦPSII of either resistant population at any timing. However, amicarbazone treatment of both susceptible populations reduced ΦPSII rapidly in both studies. Amicarbazone reduced ΦPSII of both susceptible populations more than atrazine and simazine at 1HAA, indicating amicarbazone may be more efficient at inhibiting PSII of annual bluegrass. Amicarbazone completely controlled both susceptible populations 2 weeks after application (WAA). Amicarbazone did not injure either triazine-resistant population. Annual bluegrass response to amicarbazone treatment in this study indicates cross-resistance may exist between amicarbazone and triazine-resistant annual bluegrass.
See more from this Division: C05 Turfgrass Science
See more from this Session: Graduate Student Poster Competition: Breeding, Physiology and Stress Management