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SPEEDWELL, CORN
Speedwell, Corn
[Veronica arvensis L.]
DESCRIPTION
Corn
speedwell is a small, weak, low-growing winter annual that thrives in thin open
turf and often appears in solid stands. The lower leaves of corn speedwell are
rounded and toothed, while the upper leaves are smaller and more pointed. Like
the other speedwells, the leaves are both alternate (end of stem) and opposite
(base of stem). Corn speedwell is similar in many respects to Persian and
ivyleaf speedwell. However, it has the smallest leaves of the three species.
Ivyleaf speedwell leaves are thicker and less serrated than those of either
corn or Persian speedwell. The entire corn speedwell plant is covered with
soft, fine hairs. The flowers are small, bright blue with white throats, and
nearly stalkless, whereas those of Persian and ivyleaf speedwell have stalks
that are longer than 1 mm. The seedpods are heart-shaped in all three species.
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Characteristic
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Description
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Growth Season
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winter annual weed
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Growth Habit
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prostrate, spreading
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Leaflet Number
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one
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Leaf Margin
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rounded teeth
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Leaf Hairs
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upper/lower surface
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Leaf/Leaflet Shape
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lower leaves egg-shaped or round, upper leaves linear
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Leaf Width
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1/2 - 1 inch
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Leaf Venation
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palmate
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Leaf Arrangement
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lower leaves opposite, upper leaves alternate
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Root Type
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fibrous
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Flower Color
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blue/purple
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Persian (L),
ivyleaf (M), and corn (R) speedwell
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corn speedwell
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Note: Still not
sure this is the right weed? The Turf
& Weed Identification Decision Aid may help. Check the TurfFiles glossary for definitions
of unfamiliar terms.
CULTURAL
CONTROL
Corn
speedwell is a low-growing winter annual that thrives in thin open turf and
often appears in solid stands. Winter annual broadleaf weeds germinate in the
fall or winter and grow during any warm weather, which may occur in the winter,
but otherwise remain somewhat dormant during the winter. They resume growth and
produce seed in the spring and die as temperatures increase in late spring and
early summer. They quickly invade thin turf areas especially where there is
good soil moisture. Shade may also encourage growth. A dense, vigorous turf is
the best way to reduce the encroachment of this weed. First, select adapted
turfgrass cultivars for your area and then properly fertilize, mow, and water
to encourage dense growth. Corn speedwell is similar in appearance to Persian
and ivyleaf speedwell.
CHEMICAL
CONTROL
Even though corn speedwell is
smaller than either Persian or ivyleaf speedwell, it is more difficult to
control since many of the herbicides that are effective against ivyleaf and
Persian speedwell do not work well against corn speedwell. For corn speedwell,
repeat applications of a three-way combination product at one-half the label
rate, applied 10 days apart, provide good control. Good to excellent control
can be achieved with one application of atrazine (Aatrex 4L), metsulfuron
(Manor, Blade, etc.), trifloxysulfuron (Monument), or quinclorac (Drive).
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Preemergence herbicides:
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Herbicide
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Tolerant Turfs (1)
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Average
Efficacy Rating(2)
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Range of Trial Efficacy Values, %
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Number of
Trials
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Products (3)
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atrazine*
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be, c, sa, z
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E
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0
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AAtrex 4L
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pronamide*
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be
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E
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0
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Kerb
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simazine
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be, c, sa, z
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G-E
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0
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Princep
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isoxaben
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ba, bc, be, bk, c, f, r, sa, z
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G-E
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0
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Gallery 75
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pendimethalin
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ba, be, bk, c, f, r, sa, z
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G-E
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0
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Pendulum, PRE-M, Scott's Turf Builder With Halts
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dithiopyr
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ba, bc, be, bk, c, f, r, sa, z
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G
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0
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Dimension, Quali-Pro Dithiopyr**, Vigoro Crabgrass
Preventer, Vigoro Dimension
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oxadiazon*,**
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bc, be, bk, f, r, sa, z
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G
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0
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Quali-Pro Oxadiazon, Ronstar
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prodiamine
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bc, be, bk, c, f, r, sa, z
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F-G
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0
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Barricade, Lesco Stonewall, Quali-Pro Prodiamine,
RegalKade
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Postemergence herbicides:
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Herbicide
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Tolerant Turfs (1)
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Average
Efficacy Rating(2)
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Range of Trial Efficacy Values, %
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Number of
Trials
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Products (3)
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trifloxysulfuron-sodium
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be, z
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E
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98 - 99
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2
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Monument
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glyphosate
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E
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98
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1
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Glyphosate Original, Roundup, Touchdown Pro**
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metribuzin
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be
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E
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0
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Sencor 75 Turf
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2,4-D & triclopyr*
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bk, f, r
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G
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0
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Chaser
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pronamide*
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be
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G
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0
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Kerb
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2,4-D
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be, bk, f, r, z
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F
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0
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2,4-D amine, Solution Water Soluble
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dicamba
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ba, be, bk, f, r, z
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F
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0
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Banvel, Clarity, Vanquish
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Footnotes:
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(1)
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Turfgrass Codes:
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ba
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bahiagrass
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bc
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bentgrass, creeping
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be
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bermudagrass
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bk
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bluegrass, Kentucky
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c
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centipedegrass
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f
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fescue, tall
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r
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ryegrass, perennial
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sa
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St. Augustinegrass
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z
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zoysiagrass
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blank
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No turfgrass in the database is
completely tolerant. Check label to see if chemical can be used at a reduced
rate or during the dormant season on your turfgrass.
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(2)
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Efficacy Ratings:
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E
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excellent control (90 to 100%)
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G
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good control (80 to 90%)
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F
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fair control (70 to 80%)
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Efficacy ratings are based on
herbicide trials performed by weed scientists at North Carolina State University between 1997 and 2007. The number of trials included in the efficacy ratings
is displayed in the next-to-last column. The higher this number, the more
confidence can be placed in the efficacy values. Trials may have involved
sequential applications of one or more chemical. Details of individual trials
(herbicide rates, dates of application, environmental conditions at time of
application, etc) can be viewed on the TurfFiles web site, through the Turf Weed Management
Decision Aid.
Efficacy ratings for chemicals
lacking trial data are from “Pest
Management Strategic Plan for Turfgrass in the Southern United States,”
summary of a workshop for turf experts from multiple universities held in Griffin, GA in October, 2004 and sponsored by the Southern Region Integrated Pest
Management Center.
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(3)
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Recommendations of specific
chemicals are based upon information on the manufacturer's label and
performance in a limited number of trials. Because environmental conditions
and methods of application may vary widely, performance of the chemical will
not always conform to the safety and pest control standards indicated by
experimental data. The order in which brand names are given is not an
indication of a recommendation or criticism.
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Recommendations for the use of
agricultural chemicals are included in this publication as a convenience to
the reader. The use of brand names and any mention or listing of commercial
products or services does not imply endorsement by North Carolina State University or discrimination against similar products or services not mentioned. Other
brand names may be labeled for use on turfgrasses. Individuals who use agricultural
chemicals are responsible for ensuring that the intended use complies with
current regulations and conforms to the product label. Be sure to obtain
current information about usage regulations and examine a current product
label before applying any chemical. For assistance, contact your county's
Cooperative Extension agent.
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© North Carolina State University. This information sheet was prepared
by Fred Yelverton, Bridget R. Lassiter, Gail G. Wilkerson, Leon Warren, Travis Gannon, Jenifer J. Reynolds, and Gregory S. Buol. Department of Crop
Science, College of Agriculture & Life Sciences, North Carolina State
University. Prepared July 15, 2008. Available on-line at
www.turffiles.ncsu.edu. This publication was made possible through a grant
provided by the Center for Turfgrass Environmental Research & Education
(CENTERE) whose purpose is to support worthwhile projects that will benefit
both the private sector and the public, and protect the environment.
KEYWORDS FOUND IN THIS ARTICLE:
| Oct 05, 2012 |
Sampson County Animal Waster Applicator Class
|
L. Warren
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Winter Weed Control and Overseeding Options in Coastal Bermudagrass
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| Oct 01, 2012 |
Orange County Extension
|
L. Warren
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Weed Management for Livestock Owners
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| Sep 25, 2012 |
Franklin county Extension
|
L. Warren
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Fall Turf Weed Management
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| Feb 07, 2012 |
Triangle Turfgrass Meeting
|
L. Warren
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Winter and Spring Weed Control Focusing on Amicarbazone, Celsius and Specticle
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| Jan 17, 2012 |
Virginia Turf Conference
|
F. Yelverton
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Weed Management
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| Dec 06, 2011 |
Orange County Triangle Landscape Symposium
|
L. Warren
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Weed Management in North Carolina Lawns
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| Nov 15, 2011 |
Sampson County Extension Turf Winter Weed Talk
|
L. Warren
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Fall and Winter Turf Weed Management
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| Sep 23, 2011 |
Hawaii Golf Course Superintendents Association
|
F. Yelverton
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HIGCSA New Products
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| Sep 23, 2011 |
Hawaii Golf Course Superintendents Assocaition
|
F. Yelverton
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HIGCSA Weed Management
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| Apr 28, 2011 |
NCSTMA Spring Seminar
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L. Warren
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Spring and Summer Weed Management in Athletic Fields
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| Feb 10, 2011 |
Guilford County Landscape Turfgrass Talks
|
L. Warren
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Winter and Spring Turf Weed Management
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| Dec 21, 2010 |
2010 NC Turfgrass Conference & Show
|
T. Gannon
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Advanced Turf Weed Management for LCOs
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| Nov 10, 2009 |
CS 414 CLASS
|
L. Warren
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Turfgrass Weed Management in North Carolina
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| Jan 09, 2008 |
Turfgrass of NC Conference
|
L. Warren
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Effective Landscape Weed Management
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| Jan 09, 2008 |
Turfgrass of NC Conference
|
L. Warren
|
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Proper ID and Control of Weeds
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|
| Jan 08, 2008 |
Turfgrass of NC Conference
|
T. Gannon
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Managing Difficult Landscape Weeds
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| Jan 24, 2007 |
Master Gardeners, Durham County
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L. Warren
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Winter and Spring Weed Control in Tall Fescue and Bermudagrass Turf
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| Jan 11, 2007 |
Dare County, NC
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L. Warren
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Winter and Spring Weed Control in Warm Season Turf
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| Feb 20, 2006 |
Cumberland County TCNC Demo Days
|
L. Warren
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Newer Herbicides for Late Winter Early Spring Weed Control in Turf
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| Jan 10, 2006 |
Turfgrass of NC Conference
|
M. Martin
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Making North Carolina Herbicide Recommendations Work for You
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| Jan 09, 2006 |
County Meetings
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F. Yelverton
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Weed Management in Warm & Cool-Season Turf
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| Nov 15, 2005 |
Dave Monk's Class Lecture
|
L. Warren
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Weed Management Programs for North Carolina Turfgrass Growers
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| Feb 19, 2005 |
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L. Warren
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New Herbicides for Difficult-to-Control Weeds in Turf
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| Feb 15, 2005 |
Wake Co., NC Turf Meeting
|
L. Warren
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Postemergence Winter Weed and Preemergence Crabgrass Control
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| Dec 20, 2003 |
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L. Warren
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Turfgrass Weed Management in North Carolina - Dec. 2003
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| Oct 21, 2003 |
|
L. Warren
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Turfgrass Weed Management in North Carolina - Oct. 2003
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| Sep 30, 2003 |
2003 Pitt County
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T. Gannon
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Fall Weed Control in Turf - 2003 Pitt County
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| Jan 21, 2003 |
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L. Warren
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Basic Weed Management - 2003 TCNC
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| Items: 28 |  |  |  |  |   |
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