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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
Dollarweed
and Irrigation
Since
this research summary was written in 2002, the full research article
was published in Weed Science, "Impact
of cultural factors on weed populations in St. Augustinegrass turf."
It
is commonly said without documentation that reducing irrigation
also reduces dollarweed infestation in turfgrass. The objective
was to evaluate the relationship of irrigation management and dollarweed
infestation.
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Dollarweed,
Hydrocotyle umbellata, (Bayer code HYDUM, also called pennywort)
is the most serious weed of St. Augustinegrass lawns in Florida,
and St. Augustinegrass, Stenotaphrum secundatum, is the most
widely used lawn species in Florida. A field area was
planted with sprigs of dollarweed and plugs of St. Augustinegrass,
and the two species were grown to cover intermingled. Independent
irrigation zones were programmed to provide plots representing irrigation
levels: high (daily to replace evapotranspiration), moderate (weekly
to saturate the root zone when wilted), and low (only rarely under
extreme wilt). There were eight replications. The 24
irrigation main plots were 9.4 m X 9.4 m. Canopy coverages
of dollarweed and St. Augustinegrass were estimated visually as
a percent of apparent canopy.
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figure shows the seasonal reduction in dollarweed canopy %,
depending on irrigation treatment. |
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The
null hypothesis is that variations in irrigation have no effect
on dollarweed coverage. Other management variables, fertilization,
mowing, and their interactions with irrigation, are also being evaluated
as split block treatments. Preliminary results averaged through
12 months (March 2001 through February 2002) were highly significant
(P < 0.0001) differences in dollarweed coverage among irrigation
treatments: high (35%), moderate (5%), and low (2%). Dollarweed
canopy coverage continued to decrease through the growing season,
but remained highest in the wet (daily) irrigation regime.
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