Transcript Evaluation of Triclopyr Amine for Controlling Alligator

RESTORATION OF NATIVE PLANTS THROUGH
CHEMICAL CONTROL OF ALLIGATORWEED
AT EUFAULA NATIONAL WILDIFE REFUGE
Shannon L. Allen
School of Forestry and Wildlife Sciences
ALLIGATORWEED
(Alternanthera philoxeroides)




Perennial
herb
Native to
South
America
Vegetative
reproduction
Forms thick,
interwoven
mats
ALLIGATORWEED




Reduces light
penetration
Reduces gaseous
exchange
Displaces native
plants
Reduces waterway
drainage
EUFAULA NATIONAL WILDLIFE REFUGE



Northern portion of
Walter F. George
impoundment of the
Chattahoochee River
2,300 hectares of
open water and
managed wetlands
Primary objective includes providing food and
habitat for waterfowl and other birds.
MOIST-SOIL MANAGEMENT

Maintenance of
moist-soil conditions
during growing
season to:



Promote growth of
desirable plant
species
Control undesirable
plant species
Provide food and
habitat
NATIVE WETLAND PLANTS




Sedges (Cyperus spp.)
Rushes (Rhynchospora
spp.)
Beggar ticks (Bidens
spp.)
Smartweeds
(Polygonum spp.)
HOW DO WE CONTROL ALLIGATORWEED?
OBJECTIVES


Objective 1
 Determine the rate and timing of triclopyr
and imazapyr application that most
effectively controls alligatorweed
Objective 2
 Determine the rate and timing of triclopyr
and imazapyr application that most
effectively restores native wetland plant
species
METHODS

Randomized block design

4 blocks (15 m x 40 m)
Kennedy Unit (n = 2)
 Bradley Unit (n = 2)



24 plots/block
Experimental plots
(5 m x 5 m)
METHODS

Treatments
 2 herbicides
 3 application rates
/herbicide
 low, medium, high
 3 application dates
 April, July, and
September 2004
HERBICIDE RATES


Triclopyr (935L-ha or 2.4L-plot of water)
 Low = 4.8L-ha or 12ml-plot
 Medium = 9.6L-ha or 24ml-plot
 High = 14.4L-ha or 36ml-plot
Imazapyr (467L-ha or 1.2L-plot of water)
 Low = 1.2L-ha or 3ml-plot
 Medium = 2.4L-ha or 6ml-plot
 High = 3.5L-ha or 9ml-plot
Rates within range recommended by manufacturers.
TREATMENT APPLICATION



Herbicides applied
with a 2L, CO2
pressurized
backpack sprayer
2.5 m wide,
5-nozzle boom
2 swaths per plot
PLANT SAMPLING



Pretreatment:
1 week before
application date
Post treatment:
1, 2, 3 weeks, and
1, 2, 3 months
Two subplots
(0.5 m x 0.5 m) per plot
PLANT SAMPLING

Parameters
measured:



percent cover of
each plant species
alligatorweed
density
(#stems/quadrat)
alligatorweed
height (cm)
PLANT BIOMASS



October 2004 and 2005
Alligatorweed and native
plants collected
in subplots (n = 2)
(0.25 m x 0.25 m)
Plants sorted by
species, dried to
constant mass,
and weighed
STATISTICAL ANALYSIS


Differences in plant
biomass between
fixed variables
herbicides, rates,
and application
dates were tested
with ANOVA using
PROC MIXED
Pretreatment
percent cover, stem
density, or height
were not significant
covariates
RESULTS
Native Plants
Alligatorweed
ALLIGATORWEED BIOMASS - 2004
Variable
F Value
DF
P Value
Herbicide
4.28
1,33
<0.05
Rate
4.56
2,33
<0.05
Application Date
28.11
1,33
<0.001
Herbicide x Rate
0.03
2,33
N.S.
Herbicide x
Application Date
4.32
1,33
<0.05
Rate x
Application Date
2.52
2,33
<0.1
Herbicide x Rate
x Application
Date
0.49
2,33
N.S.
ALLIGATORWEED BIOMASS - 2004
140
100
a
80
a
60
ab
b
bc
40
c
c
20
c
)
Low
M ed
H igh
120
2
120
A llig a to rw e e d (g /0 .2 5 m
T riclopyr
Im azapyr
2
A llig a to rw e e d d ry m a ss (g /0 .2 5 m )
140
100
a
80
ab
60
bc
40
c
bc
c
20
0
0
April
April
July
July
A pplication date
April
July
A pplication date
NATIVE PLANT BIOMASS - 2004
Variable
F Value
DF
P Value
Herbicide
3.48
1,33
<0.1
Rate
1.00
2,33
N.S.
Application Date
8.88
1,33
<0.05
Herbicide x Rate
0.25
2,33
N.S.
Herbicide x
Application Date
0.38
1,33
N.S.
Rate x
Application Date
3.20
2,33
0.05
Herbicide x Rate
x Application
Date
0.18
2,33
N.S.
NATIVE PLANT BIOMASS - 2004
2
N a tiv e p la n t d ry m a s s (g /0 .2 5 m )
140
2
N a tiv e p la n t d ry m a ss (g /0 .2 5 m )
140
120
100
80
a
60
b
40
20
Low
M ed
H igh
a
120
ab
100
80
ab
60
b
b
b
40
20
0
0
Triclopyr
Imazapyr
H erbicide
April
A pplication date
July
ALLIGATORWEED VS NATIVE PLANTS
A llig a to rw e e d (g /0 .2 5 m
100
a
80
ab
60
bc
40
c
bc
c
20
Low
M ed
H igh
a
120
2
120
140
N a tiv e p la n t (g /0 .2 5 m )
Low
M ed
H igh
2
)
140
ab
100
80
ab
60
b
b
b
40
20
0
0
April
July
A pplication date
April
July
A pplication date
PERCENT COVER OF ALLIGATORWEED
AFTER APRIL TREATMENT
100
80
70
Low
M edium
H igh
C ontrol
90
A llig a to rw e e d % c o v e r
90
A llig a to rw e e d % c o v e r
100
Low
M edium
H igh
C ontrol
60
50
40
30
20
80
70
60
50
40
30
20
10
10
0
0
0
2
4
6
8
W eeks after treatm ent
Triclopyr
10
12
0
2
4
6
8
W eeks after treatm ent
Imazapyr
10
12
PERCENT COVER OF ALLIGATORWEED
AFTER JULY TREATMENT
Low
M edium
H igh
C ontrol
A llig a to rw e e d % c o v e r
90
80
70
60
50
40
30
20
100
Low
M edium
H igh
C ontrol
90
A llig a to rw e e d % c o v e r
100
80
70
60
50
40
30
20
10
10
0
0
0
2
4
6
8
W eeks after treatm ent
Triclopyr
10
12
0
2
4
6
8
W eeks after treatm ent
Imazapyr
10
12
SUMMARY - 2004
1) Alligatorweed:





In April, imazapyr controls better than
triclopyr
Herbicides control equally at July
application
July application controls better than April
application
In April, high application rate more
effective than medium and low rates
In July, no difference between rates
SUMMARY - 2004
2) Native plants:



Triclopyr results in greater biomass than
imazapyr
In April, high rate results in greater
biomass than low rate
High rate in April results in greater
biomass than high rate in July
ALLIGATORWEED BIOMASS - 2005
Variable
F Value
DF
P Value
Herbicide
0.02
1,33
N.S.
Rate
3.45
2,33
<0.05
Application Date
22.07
1,33
<0.001
Herbicide x Rate
1.18
2,33
N.S.
Herbicide x
Application Date
6.21
1,33
<0.05
Rate x
Application Date
0.00
2,33
N.S.
Herbicide x Rate
x Application
Date
1.33
2,33
N.S.
ALLIGATORWEED BIOMASS - 2005
2
A lligatorw eed (g/0.25m )
250
200
150
100
a
ab
50
b
0
Low
Medium
High
A p p licatio n R ate
NATIVE PLANT BIOMASS - 2005
Variable
F Value
DF
P Value
Herbicide
0.04
1,33
N.S.
Rate
1.30
2,33
N.S.
Application Date
8.94
1,33
<0.01
Herbicide x Rate
1.03
2,33
N.S.
Herbicide x
Application Date
7.19
1,33
<0.05
Rate x
Application Date
0.08
2,33
N.S.
Herbicide x Rate
x Application
Date
0.18
2,33
N.S.
ALLIGATORWEED VS NATIVE PLANTS
250
250
2
200
N a tiv e p la n t (g /0 .2 5 m )
2
A llig a to rw e e d (g /0 .2 5 m )
a
T riclopyr
Im azapyr
150
100
a
ab
50
bc
200
T riclopyr
Im azapyr
bc
abc
150
c
100
50
c
0
0
April
July
A pplication date
April
July
A pplication date
SUMMARY - 2005
1) Alligatorweed:




High application rate controls better than
low rate
No difference between herbicides at April
or July application
July application of imazapyr better than
April application
No difference in control by triclopyr at
April or July application
SUMMARY - 2005
2) Native plants:



No difference between herbicides at April
and July application
No difference between April and July with
triclopyr application
Greater native plant biomass with July
application of imazapyr than April
application
MANAGEMENT RECOMMENDATION

To manage for native wetland plants in
treatment year:

Apply high rate of triclopyr in April to control
alligatorweed and allow greatest native plant
biomass
MANAGEMENT RECOMMENDATION

To manage for native wetland plants one
year after treatment:

Apply high rate of imazapyr in July for greatest
control of alligatorweed and highest native plant
biomass one year after treatment
ACKNOWLEDGEMENTS:
Committee members: Dr. Gary R. Hepp, Dr. Bob
S. Boyd, Dr. James H. Miller, and Dr. Ralph E.
Mirarchi
Field Technicians: Erwin Chambliss, Frank Allen,
Frank and Betty Tee Smith
Refuge Staff (Frank Dukes and especially Milton
Hubbard)
Funding: U.S. Fish and Wildlife Service, BASF,
and SePro