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 Academic
Programs
Certificate
Program
Classes
by Phil Busey
Degree
Requirements
Golf
and Sports Turf
Grass
Biology
Landscape
IPM
Living
Lawn
Turfgrass
Culture
Research
Interests
Weed
Science
Weeds
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Weed
Science
Kyllinga
and Signalgrass
Abstract
(Full Paper below)
In
a mixed weed population, an optimum herbicide strategy maximizes
turf canopy coverage and health.
The
objective was to study the effect of postemergence herbicides alone
and in mixtures on populations of green kyllinga (Kyllinga brevifolia
Rottb.), tropical signalgrass (Urochloa subquadripara (Trin.) R.D.
Webster), and 'Tifgreen' bermudagrass turf (Cynodon transvaalensis
Burtt-Davy x C. dactylon (L.) Pers.) Initial coverage
was green kyllinga, 43%; tropical signalgrass, 29%; and bermudagrass,
28%. There were 12 herbicide treatments, including a water control,
in five replications. Treatments were bentazon, 1.12 kg ha-1; halosulfuron,
0.07 kg ha-1; imazaquin, 0.56 kg ha-1; and MSMA, 2.52 kg ha-1 applied
alone and in all binary combinations, plus MSMA + metribuzin at
0.28 kg ha-1. Halosulfuron and imazaquin rates were reduced
in half in mixtures.
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There
were two sets of applications separated by 11 weeks, each with two
applications split by 10-11 days. Treatments with halosulfuron
or imazaquin were applied only once per set of applications.
Only treatments with halosulfuron, imazaquin, or MSMA + metribuzin
injured (P < 0.05) green kyllinga. Only treatments with MSMA
injured tropical signalgrass. Only MSMA + metribuzin and MSMA
+ halosulfuron injured green kyllinga and tropical signalgrass,
but did not maximize bermudagrass coverage. The optimum treatments,
bentazon + MSMA and MSMA alone, increased bermudagrass coverage
to 97% and 94%, respectively, compared with 43% for the water control.
Although imazaquin did not injure bermudagrass, it reduced bermudagrass
coverage to 13%. In removing kyllinga, imazaquin had opened
a niche that was colonized by tropical signalgrass at the expense
of bermudagrass. The optimum herbicide strategy must consider
not only injury to weeds but competition among weeds.
The
following download requires the Adobe Acrobat
Reader 
Full
Paper:
Busey, P. 2001. Optimum herbicide
strategy for managing mixed weed populations in the Southern U.S.
(128 KB)
Internat. Turfgrass Soc. Res. J. 9:1001-1004.
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