Tuesday, November 6, 2007
170-16
Poa trivialis Control with Bispyribac-sodium and Sulfosulfuron in Creeping Bentgrass.
Bispyribac-sodium and sulfosulfuron are new ALS-inhibiting herbicides registered for use in creeping bentgrass fairways for selective roughstalk bluegrass control but limited comprehensive investigations have been conducted to evaluate efficacy for long-term management. Field experiments were conducted from June 2005 to October 2006 (Study 1) and from June 2006 to October 2006 (Study 2) on a fairway at New Jersey National Golf Club in Basking Ridge , NJ . Bispyribac-sodium was applied twice at 37, 74, or 111 g a.i./ha or thrice at 37 or 74 g/ha. Sulfosulfuron was applied twice or thrice at 6.5, 13, or 26 g a.i./ha or once at 26 g/ha. Initial applications were made June 10, 2005 and June 1, 2006 and sequential applications were made at three week intervals. Applications were made at 220 L/ha and a non-ionic surfactant was included at 0.25% v/v for sulfosulfuron treatments. Creeping bentgrass chlorosis from herbicides was acceptable (< 20%) by 2 to 3 weeks after applications while all treatments provided substantial reductions in roughstalk bluegrass cover (>90%) by late July. However, roughstalk bluegrass had regrown by October in both years suggesting herbicide applications visually eliminated foliage but did not control vegetative reproductive structures. Since roughstalk bluegrass has a wide genetic diversity, further investigations are needed to determine if these results are correlated with biotype tolerance to herbicide applications or from ineffective herbicide translocation. Overall, bispyribac-sodium and sulfosulfuron effectively eliminated roughstalk bluegrass ground cover in summer months but regrowth during fall months prevented long-term successful control.
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