Annual bluegrass control in some cool-season turfgrasses by bispyribac sodium

Abstract

Selective herbicidal activity of bispyribac sodium between cool-season turf grasses and annual bluegrass, and its inhibitory effect on heading and flowering of the weed were investigated in a glasshouse and/or fields.
Bispyribac sodium did not affect the growth of annual bluegrass applied at pre-emergence but showed excellent effectiveness when applied at post-emergence.
Annual type of annual bluegrass was more susceptible to bispyribac sodium than perennial type, and younger plants of both types were more susceptible than the older plants.
Bispyribac sodium showed good selectivity between four cool-season turf grasses (tall fescue, perennial ryegrass, bentgrass and Kentucky bluegrass) and annual bluegrass.
The degree of tolerance of the cool-season turf grasses to bispyribac sodium was in the order of perennial ryegrass ≥tall fescue>bentgrass>Kentucky bluegrass.
Bispyribac caused a transient chlorosis on the four cool-season turfgrasses at higher rates, however, the symptom disappeared within 25 days after the treatment. Selectivity of bispyribac sodium between the turfgrasses and annual bluegrass is larger in later application than in earlier application.
Bispyribac sodium strongly inhibited heading and flowering of annual bluegrass at the rate of 0.003 g a.i./m²for 4 weeks after the application in the fields as well.
These results suggest that bispyribac sodium can be used effectively tool for annual bluegrass control in cool-season turfgrasses.