Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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ROUGHSTALK BLUEGRASS CONTROL WITH BISPYRIBAC-SODIUM AND
SULFOSULFURON. P. McCullough and S. Hart, Rutgers Univ., New Brunswick, NJ.
ABSTRACT
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 longterm
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 successful longterm
control.
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