Abstract:
Temperate climates are particularly conducive to
growth of annual bluegrass which readily invades and
dominates most cool-season turfgrasses. Ethofumesate
(2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl
methanesulfonate) is one herbicide available which will
selectively control annual bluegrass.
The primary objectives of this research were to
determine optimum application rates and timing of
ethofumesate for control of annual bluegrass on sites
renovated by three different techniques. In addition,
tolerance of common turfgrass cultivars was determined.
Ethofumesate rates of 0.5, 1.0, 1.5 kg ai/ha, and split
repeat treatments of 0.5 kg ai/ha applied twice or three
times, applied preemergence, or early postemergence at
the one and two leaf stage relative to perennial ryegrass
were tested. Protected Least Significant Difference
mean separation statistical analysis was used to
determine differences at the 5% level.
Differences were observed between ryegrass and
tall fescue cultivars in greenhouse ethofumesate
tolerance studies but not in field trials. Ethofumesate
greenhouse cultivar tolerance differences did not
correlate to results of field trials. All perennial
ryegrass and tall fescue cultivars tested in field
trials tolerated ethofumesate well at all rates.
There was an initial 1 month period of growth suppression
following ethofumesate application which perennial
ryegrass and tall fescue appeared able to
recover and annual bluegrass was not. Annual bluegrass
was controlled in all trials at 0.5, 0.5 X 2, 0.5 X 3,
1.0, and 1.5 kg ai/ha ethofumesate rates and at all
stages of application. Annual bluegrass reduction
ranged between 83% to 100%.
Perennial ryegrass cultivars Palmer, Blazer,
Loretta, Dasher, and Regal, tall fescue cultivar
Mustang, and 'America' Kentucky bluegrass tolerated
ethofumesate. Red fescue, hard fescue, chewings
fescue, roughstalk bluegrass, colonial bentgrass, and
annual bluegrass did not tolerate ethofumesate.
In the three establishment methods studied, annual
bluegrass control was 100% in the no-till followed by
surface scarification and broadcast seeding, 97.3% in
the till trials with broadcast seeding, and 83% in the
no till slicer seeder method.
