٥ RESTORATION OF NATIVE PLANTS THROUGH CHEMICAL CONTROL OF ALLIGATORWEED AT EUFAULA NATIONAL...

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RESTORATION OF NATIVE PLANTS THROUGH CHEMICAL RESTORATION OF NATIVE PLANTS THROUGH CHEMICAL

CONTROL OF ALLIGATORWEED CONTROL OF ALLIGATORWEED

AT EUFAULA NATIONAL WILDIFE REFUGEAT EUFAULA NATIONAL WILDIFE REFUGE

Shannon L. AllenShannon L. Allen

School of Forestry and Wildlife SciencesSchool of Forestry and Wildlife Sciences

ALLIGATORWEEDALLIGATORWEED ( (Alternanthera philoxeroidesAlternanthera philoxeroides))

Perennial Perennial herbherb

Native to Native to South South AmericaAmerica

Vegetative Vegetative reproductionreproduction

Forms thick, Forms thick, interwoven interwoven matsmats

ALLIGATORWEEDALLIGATORWEED

Reduces Reduces light light penetrationpenetration

Reduces gaseous Reduces gaseous exchangeexchange

DisplacesDisplaces native native plantsplants

Reduces waterway Reduces waterway drainagedrainage

http://images.google.com/imgres?imgurl=http://www.niwa.co.nz/rc/prog/aquaticplants/news/mayhem2_large.jpg&imgrefurl=http://www.niwa.co.nz/rc/prog/aquaticplants/news/mayhem2_large.jpg/view&h=303&w=518&sz=47&tbnid=S970ayaX1MwJ:&tbnh=74&tbnw=127&start=44&prev=/images%3Fq%3DALLIGATOR%2BWEED%26start%3D40%26hl%3Den%26lr%3D%26sa%3DN

EUFAULA NATIONAL WILDLIFE REFUGEEUFAULA NATIONAL WILDLIFE REFUGE

Northern portion of Northern portion of Walter F. George Walter F. George impoundment of the impoundment of the Chattahoochee RiverChattahoochee River

2,300 hectares of 2,300 hectares of open water and open water and managed wetlandsmanaged wetlands

Primary objective includes providingPrimary objective includes providing food and food and habitat for waterfowl and other birdshabitat for waterfowl and other birds..

MOIST-SOIL MANAGEMENTMOIST-SOIL MANAGEMENT Maintenance of Maintenance of

moist-soil conditions moist-soil conditions during growing during growing season to:season to:

Promote growthPromote growth of of desirable plant desirable plant speciesspecies

Control Control undesirable undesirable plant speciesplant species

Provide Provide food food and and habitathabitat

NATIVE WETLAND PLANTSNATIVE WETLAND PLANTS

Sedges (Sedges (CyperusCyperus spp.) spp.)

Rushes (Rushes (RhynchosporaRhynchospora spp.)spp.)

Beggar ticks (Beggar ticks (Bidens Bidens spp.)spp.)

Smartweeds Smartweeds ((PolygonumPolygonum spp.) spp.)

HOW DO WE CONTROL ALLIGATORWEED?HOW DO WE CONTROL ALLIGATORWEED?

OBJECTIVESOBJECTIVES

Objective 1Objective 1 Determine the rate and timing of triclopyr Determine the rate and timing of triclopyr

and imazapyr application that most and imazapyr application that most effectively controls alligatorweed effectively controls alligatorweed

Objective 2Objective 2 Determine the rate and timing of triclopyr Determine the rate and timing of triclopyr

and imazapyr application that most and imazapyr application that most effectively restores native wetland plant effectively restores native wetland plant speciesspecies

METHODSMETHODS

Randomized block designRandomized block design

4 blocks (15 m x 40 m)4 blocks (15 m x 40 m) Kennedy Unit (Kennedy Unit (n = n = 2)2) Bradley Unit (Bradley Unit (n n = 2)= 2)

24 plots/block24 plots/block

Experimental plots Experimental plots

(5 m x 5 m)(5 m x 5 m)

TreatmentsTreatments 2 2 herbicidesherbicides 3 3 application ratesapplication rates

/herbicide /herbicide low, medium, highlow, medium, high

3 3 application datesapplication dates April, July, and April, July, and

September 2004September 2004

METHODSMETHODS

HERBICIDE RATESHERBICIDE RATES

Triclopyr Triclopyr (935L(935L-ha-ha or 2.4L or 2.4L-plot -plot of water)of water) Low = 4.8LLow = 4.8L-ha -ha or 12mlor 12ml-plot-plot

Medium = 9.6LMedium = 9.6L-ha-ha or 24ml or 24ml-plot-plot

High = 14.4LHigh = 14.4L-ha-ha or 36ml or 36ml-plot-plot

Imazapyr Imazapyr (467L(467L-ha-ha or 1.2L or 1.2L-plot-plot of water) of water) Low = 1.2LLow = 1.2L-ha-ha or 3ml or 3ml-plot-plot

Medium = 2.4LMedium = 2.4L-ha-ha or 6ml or 6ml-plot-plot

High = 3.5LHigh = 3.5L-ha-ha or 9ml or 9ml-plot-plot

Rates within range recommended by Rates within range recommended by manufacturers.manufacturers.

TREATMENT APPLICATIONTREATMENT APPLICATION

Herbicides applied Herbicides applied with a 2L, COwith a 2L, CO22 pressurized pressurized backpack backpack sprayersprayer

2.5 m wide, 2.5 m wide,

5-nozzle boom5-nozzle boom

2 swaths per plot2 swaths per plot

PLANT SAMPLINGPLANT SAMPLING

PretreatmentPretreatment: : 1 week before 1 week before

application dateapplication date

Post treatmentPost treatment: : 1, 2, 3 weeks, and1, 2, 3 weeks, and 1, 2, 3 months1, 2, 3 months

Two subplotsTwo subplots

(0.5 m x 0.5 m) per plot(0.5 m x 0.5 m) per plot

PLANT SAMPLINGPLANT SAMPLING

Parameters Parameters measured:measured:

percent coverpercent cover of of each plant specieseach plant species

alligatorweed alligatorweed density density (#stems/quadrat)(#stems/quadrat)

alligatorweed alligatorweed height height (cm)(cm)

PLANT BIOMASSPLANT BIOMASS

October October 20042004 and and 20052005

AlligatorweedAlligatorweed and and nativenative

plantsplants collected collected

in subplots (in subplots (nn = 2) = 2)

(0.25 m x 0.25 m) (0.25 m x 0.25 m)

Plants sorted byPlants sorted by

species, species, dried dried to to

constant mass, constant mass,

and and weighedweighed

STATISTICAL ANALYSISSTATISTICAL ANALYSIS

Differences in plant Differences in plant biomass between biomass between fixed variables fixed variables herbicides, rates, herbicides, rates, and application and application dates were tested dates were tested with ANOVA using with ANOVA using PROC MIXEDPROC MIXED

Pretreatment Pretreatment percent cover, stem percent cover, stem density, or height density, or height were not significant were not significant covariatescovariates

RESULTSRESULTS

Native Plants

Alligatorweed

ALLIGATORWEED BIOMASS - 2004ALLIGATORWEED BIOMASS - 2004

VariableVariable F ValueF Value DFDF P ValueP ValueHerbicideHerbicide 4.284.28 1,331,33 <0.05<0.05

RateRate 4.564.56 2,332,33 <0.05<0.05

Application Application DateDate

28.1128.11 1,331,33 <0.001<0.001

Herbicide x Herbicide x RateRate

0.030.03 2,332,33 N.S.N.S.

Herbicide x Herbicide x Application Application

DateDate

4.324.32 1,331,33 <0.05<0.05

Rate x Rate x Application Application

DateDate

2.522.52 2,332,33 <0.1<0.1

Herbicide x Herbicide x Rate x Rate x


0.490.49 2,332,33 N.S.N.S.


Application date

Allig

ator

wee

d (g

/0.2

5m2 )

0

20

40

60

80

100

120

140LowMedHigh

a

ab

bc

c bc

c

April July

ab

a

bc

c

Application date

Alli

gato

rwee

d dr

y m

ass (

g/0.

25m

2 )

0

20

40

60

80

100

120

140

TriclopyrImazapyr

a

b

c

c

April July April July

NATIVE PLANT BIOMASS - 2004NATIVE PLANT BIOMASS - 2004

VariableVariable F ValueF Value DFDF P ValueP ValueHerbicideHerbicide 3.483.48 1,331,33 <0.1<0.1

RateRate 1.001.00 2,332,33 N.S.N.S.


8.888.88 1,331,33 <0.05<0.05


0.250.25 2,332,33 N.S.N.S.


DateDate

0.380.38 1,331,33 N.S.N.S.


DateDate

3.203.20 2,332,33 0.050.05



0.180.18 2,332,33 N.S.N.S.


Herbicide

Nat

ive

plan

t dry

mas

s (g/

0.25

m2 )

0

20

40

60

80

100

120

140

a

b

Triclopyr Imazapyr

Application date

Nat

ive

plan

t dry

mas

s (g

/0.2

5m2 )

0

20

40

60

80

100

120

140

LowMedHigh

b

ab

a

ab

b

b

April July

ALLIGATORWEED ALLIGATORWEED VSVS NATIVE PLANTS NATIVE PLANTS

Application date

Allig

ator

wee

d (g

/0.2

5m2 )

0

20

40

60

80

100

120

140LowMedHigh

a

ab

bc

c bc

c

Application date

Nat

ive

plan

t (g/

0.25

m2 )

0

20

40

60

80

100

120

140LowMedHigh

b

ab

a

ab

b

b


PERCENT COVER OF ALLIGATORWEED PERCENT COVER OF ALLIGATORWEED AFTER APRIL TREATMENTAFTER APRIL TREATMENT

Weeks after treatment

0 2 4 6 8 10 12

Allig

ator

weed

% c

over

0

10

20

30

40

50

60

70

80

90

100LowMediumHighControl

Triclopyr Imazapyr


0 2 4 6 8 10 12

Allig

ator

weed

% c

over

0

10

20

30

40

50

60

70

80

90


PERCENT COVER OF ALLIGATORWEED PERCENT COVER OF ALLIGATORWEED AFTER JULY TREATMENTAFTER JULY TREATMENT

TriclopyrTriclopyr Imazapyr Imazapyr


0 2 4 6 8 10 12

Allig

ator

weed

% c

over

0

10

20

30

40

50

60

70

80

90



0 2 4 6 8 10 12

Allig

ator

weed

% c

over

0

10

20

30

40

50

60

70

80

90


SUMMARY - 2004SUMMARY - 20041) Alligatorweed:1) Alligatorweed:

In April, imazapyr controls better than In April, imazapyr controls better than triclopyrtriclopyr

Herbicides control equally at July Herbicides control equally at July applicationapplication

July application controls better than April July application controls better than April applicationapplication

In April, high application rate more In April, high application rate more effective than medium and low rateseffective than medium and low rates

In July, no difference between ratesIn July, no difference between rates

SUMMARY - 2004SUMMARY - 2004

2) Native plants:2) Native plants:

Triclopyr results in greater biomass than Triclopyr results in greater biomass than imazapyrimazapyr

In April, high rate results in greater In April, high rate results in greater biomass than low ratebiomass than low rate

High rate in April results in greater High rate in April results in greater biomass than high rate in Julybiomass than high rate in July


VariableVariable F ValueF Value DFDF P ValueP ValueHerbicideHerbicide 0.020.02 1,331,33 N.S.N.S.

RateRate 3.453.45 2,332,33 <0.05<0.05


22.0722.07 1,331,33 <0.001<0.001


1.181.18 2,332,33 N.S.N.S.


DateDate

6.216.21 1,331,33 <0.05<0.05


DateDate

0.000.00 2,332,33 N.S.N.S.



1.331.33 2,332,33 N.S.N.S.


Application Rate

All

igat

orw

eed

(g/0

.25m

2 )

0

50

100

150

200

250

a ab

b

Low Medium High


VariableVariable F ValueF Value DFDF P ValueP ValueHerbicideHerbicide 0.040.04 1,331,33 N.S.N.S.

RateRate 1.301.30 2,332,33 N.S.N.S.


8.948.94 1,331,33 <0.01<0.01


1.031.03 2,332,33 N.S.N.S.


DateDate

7.197.19 1,331,33 <0.05<0.05


DateDate

0.080.08 2,332,33 N.S.N.S.



0.180.18 2,332,33 N.S.N.S.

ALLIGATORWEED ALLIGATORWEED VSVS NATIVE PLANTS NATIVE PLANTS

Application date

Allig

ator

wee

d (g

/0.2

5m2 )

0

50

100

150

200

250

Triclopyr Imazapyr

a

ab bc

c

Application date

Nat

ive

plan

t (g

/0.2

5m2 )

0

50

100

150

200

250

TriclopyrImazapyr

bc

c

abc

a



1) Alligatorweed:1) Alligatorweed:

High application rate controls better than High application rate controls better than low ratelow rate

No difference between herbicides at April No difference between herbicides at April or July applicationor July application

July application of imazapyr better than July application of imazapyr better than April applicationApril application

No difference in control by triclopyr at No difference in control by triclopyr at April or July applicationApril or July application


2) Native plants:2) Native plants:

No difference between herbicides at No difference between herbicides at April and July applicationApril and July application

No difference between April and July No difference between April and July with triclopyr applicationwith triclopyr application

Greater native plant biomass with July Greater native plant biomass with July application of imazapyr than April application of imazapyr than April applicationapplication

MANAGEMENT RECOMMENDATIONMANAGEMENT RECOMMENDATION

To manage for native wetland plants in To manage for native wetland plants in treatment year:treatment year: Apply high rate of triclopyr in April to control Apply high rate of triclopyr in April to control

alligatorweed and allow greatest native plant alligatorweed and allow greatest native plant biomassbiomass

MANAGEMENT RECOMMENDATIONMANAGEMENT RECOMMENDATION To manage for native wetland plants one To manage for native wetland plants one

year after treatment:year after treatment: Apply high rate of imazapyr in July for greatest Apply high rate of imazapyr in July for greatest

control of alligatorweed and highest native control of alligatorweed and highest native plant biomass one year after treatmentplant biomass one year after treatment

ACKNOWLEDGEMENTS:ACKNOWLEDGEMENTS: Committee membersCommittee members: Dr. Gary R. Hepp, Dr. : Dr. Gary R. Hepp, Dr. Bob S. Boyd, Dr. James H. Miller, and Dr. Ralph Bob S. Boyd, Dr. James H. Miller, and Dr. Ralph

E. MirarchiE. Mirarchi

Field TechniciansField Technicians: Erwin Chambliss, Frank Allen, : Erwin Chambliss, Frank Allen, Frank and Betty Tee SmithFrank and Betty Tee Smith

Refuge StaffRefuge Staff (Frank Dukes and especially Milton (Frank Dukes and especially Milton Hubbard)Hubbard)

FundingFunding: U.S. Fish and Wildlife Service, BASF, : U.S. Fish and Wildlife Service, BASF, and SeProand SePro

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