Hawkweed Control in Alaska - University of Alaska … hawkweed Seefeldt.pdfhawkweed, grasses, and...
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Hawkweed Control in Alaska Steven Seefeldt
Transcript of Hawkweed Control in Alaska - University of Alaska … hawkweed Seefeldt.pdfhawkweed, grasses, and...
Hawkweed Control in Alaska
Steven Seefeldt
Background
• Hieracium
– About 800 species world wide
Background
• Hieracium
– About 800 species world wide
– Hierax = hawk. It was thought that the great
vision of hawks was due to their supposed
addiction to these plants
Background
• Hieracium
– About 800 species world wide
– Hierax = hawk. It was thought that the great
vision of hawks was due to their supposed
addiction to these plants
– “Certainly the eye of a hawk is needed to
distinguish the host of species” Lewis J. Clark
Background
• Native Hieracium species in AK
– albiflorum White
– umbellatum Narrow leaved
– tristi Alpine
– scouleri var. albertinum Western
Background
• Introduced Hieracium species in AK
– aurantiacum Orange
– caespitosum Meadow
– murorum Wall
– lachenalii Western/common
– pilosella Mouse ear
– sabaudum New England
Orange Hawkweed
Meadow Hawkweed
Meadow Hawkweed
Wall Hawkweed
Western/common Hawkweed
Mouseear Hawkweed
New England Hawkweed
New England Hawkweed
Red = western/common
Yellow = mouseear
Blue = Meadow
Green = narrow leaved
Hawkweed reproduction
• Flowers from rosettes, typically get one
stalk
• Each stem with multiple flower heads
• Each head with multiple seeds
• Seeds dispersed by wind and easily
carried on vehicles, animals and clothes
• Many species have stolons
Whitehorse
Orange Hawkweed in Alaska
• First identified in Juneau in 1961
• Starting to become more widespread
Orange Hawkweed management
• Information from the south
– Mechanical methods not effective
• Mowing increases vegetative spread
• Plowing spreads
• Digging difficult
Orange Hawkweed management
• Information from the south
– Mechanical methods not effective
• Mowing increases vegetative spread
• Plowing spreads
• Digging difficult
– No biological agents
Orange Hawkweed management
• Information from the south
– Mechanical methods not effective
• Mowing increases vegetative spread
• Plowing spreads
• Digging difficult
– No biological agents
– Herbicides
• Must have surfactant to get past leaf hairs
• Must apply during rosette stage
Talkeetna Weed Pull
Methods:
• 2 x 2 meter plots
• 8 treated plots, 8
control plots
• Pre-treatment % cover
estimates
• Hand pulled each
treated plot (biomass of
orange hawkweed
including roots and
stolons)
Post-Pull (8/6/2007)
6 weeks after pull
Post-Pull (6/25/2007)
End of the day
Post-Pull (8/6/2007)
6 weeks after pull
Orange Hawkweed management
• Herbicides used in the south
– 2,4-D 2,4-D
– Banvel Dicamba
– Transline Clopyralid
– Curtail Clopyralid + 2,4-D
– Redeem R&P Clopyralid + triclopyr
– Milestone Aminopyralid
Greenhouse Study
• Clopyralid + Triclopyr (Redeem R&P)
• Aminopyralid (Milestone)
• Clopyralid (Transline)
Greenhouse Study
Greenhouse Study
Greenhouse Study
• Used 6 herbicide rates 1, 1/2, 1/4, 1/8,
1/16 and 0 times the full label rate
• Sprayed 10 plants at each rate when at
the 8 leaf rosette stage
• Visually rated damage after 3 weeks
• Cut plants at ground level, dried and
weighed
• Experiment conducted twice
Greenhouse results – Redeem
Greenhouse results - Milestone
Greenhouse results - Transline
Greenhouse results
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Re Mi Tr
0
1/16
1/8
1/4
1/2
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Re Mi Tr
0
1/16
1/8
1/4
1/2
1
Weig
ht
(gra
ms)
First trial Second trial
First trial Second trial
Field Trials
• Five sites, Talkeetna and
Homer
• Plots 6 x 30 feet
• Three herbicides at three
rates (1, ½, and ¼ the full
rate plus a control)
• Three replications of each
of the above treatments
• Randomized complete
block
2007 Field Trials
Pre-treatment Measurements:
• Two ¼ x ¼ m sub-plots per plot
• % cover estimates of orange
hawkweed, grasses, and forbs
Post-treatment Measurements:
• Rate plots visually based on
herbicide damage, 0% (no damage)
to 100% (dead) after three weeks
• End of season harvest ¼ x ¼ m
sub-plots and separate by cover
type
• Rate plots visually the following year
The work in Homer, AK
Control area
Biomass harvest Milestone 1x
Visual Injury - Redeem
0
10
20
30
40
50
60
70
80
90
Perc
en
t in
jury
0.25 0.5 1
Herbicide rate (1 = 2.3 L/ha)
A
C
B
Visual Injury - Milestone
0
10
20
30
40
50
60
70
80
90
Perc
en
t in
jury
0.125 0.25 0.5 1
Herbicide rate (1 = 0.12 kg/ha)
C
A A
B
Visual Injury - Transline
0
10
20
30
40
50
60
70
80
Perc
en
t in
jury
0.25 0.5 1
Herbicide rate (1 = 1.1 kg/ha)
B
AB
A
Orange Hawkweed control
0
10
20
30
40
50
60
70
80
Perc
en
t d
ry w
eig
ht
0.125 0.25 0.5 1
Herbicide rate
Milestone Redeem Transline
Impact on Grasses
0
50
100
150
200
250
300
350
Perc
en
t d
ry w
eig
ht
0.125 0.25 0.5 1
Herbicide rate
Milestone Redeem Transline
Impact on broadleaves
0
20
40
60
80
100
120
140
Perc
en
t d
ry w
eig
ht
0.125 0.25 0.5 1
Herbicide rate
Milestone Redeem Transline
What were the other plants
Milestone Redeem Transline
----------------- % injury -----------------
Dandelion 100-72 98-83 81-73
Clover 100-53 100-80 73-57
Yarrow 25 100-50 70-50
Geranium 0 100 -
Conclusion
• Three herbicides are promising for use on
orange hawkweed and one (Milestone) is
effective at reduced rates based on
greenhouse and field research
Conclusion
• Three herbicides are promising for use on
orange hawkweed and one (Milestone) is
effective at reduced rates based on
greenhouse and field research
• Grasses increased as orange hawkweed
decreased
Warnings
• From the book Wild Flowers of the Pacific
Northwest by Lewis J. Clark
– Pg 561 – “Introduce into one’s garden with
peril”
Acknowledgements
• ARS – Jeff Conn, Joseph Kuhl, Dan Hall, Erin
Carr, Nan Werdin-Pfisterer, Trista Saunders,
Jennifer Kapla, Steve Lillard, Zachary Behr,
Katie Mohrmann, and Katie DiCristina
• AK - Caleb Slemmons, Gino Graziano, Steve
Hicks, Jen Vaughan, and Emily Perchuzel
• Weed pullers of the Youth Conservation Corps
and Talkeeta citizens
• Four land owners
