Eucalyptus Control in Natural Areas and

Rights of Way

Patrick J. Minogue

Kimberly A. Lorentz

Aquatic Weed Control Short Course

May 5, 2015

South Florida

6 Month old Eucalyptus grandis, 6-9 ft height

Eucalyptus biology

• More than 800 diverse species of Eucalyptus (Myrtaceae), native to Australia and Polynesia

• Over 70 species are planted elsewhere for energy wood, windbreaks, pulpwood, and recently for mulch wood in Florida

• Perennial growth form, prolific seed production (4,000 seeds m-2), low incidence of disease, pest resistance, drought tolerance, rapid growth rates, and ability to grow in infertile soil (Booth 2012).

• Eight species are considered invasive in the world (Rejmánekand Richardson 2013).

• Requires disturbance for recruitment and intensive culture for plantation establishment (Da Silva et al. 2010)

• Seed are generally very small (1-3 mm) and germination varies from 11 to 98% (USDA 2008).

Eucalyptus Invasiveness - Risks

• Considered invasive in some parts of their

introduced range in South Africa, Hawaii,

Coastal California

• Undesirable Economic Impacts:

Increased fire intensity (Pagni 1992)

Reduced river flows (Le Maitre, et al. 2002)

Altered faunal composition and density (Sax

2002)

Prevention• Avoidance through appropriate risk assessments

and quarantine enforcement (McCormick and Howard 2013), is often considered the most cost effective approach in dealing with biological invasions (Leung et al. 2002).

• Two approaches needed to assess risk:

Quantitative Risk Assessment

Field Assessment is needed to evaluate environmental context

Need to identify containment and cost-effective direct control protocols

• Cut stump 80% Garlon® 4 or 100% Garlon® 3A, Stalker®

or Roundup® (Bossard et al. 2000).

• 50% Roundup Cut Stump,

or 50% Garlon® basal bark,

basal frill (Moore 2008).

• Multiple treatments

• Needs:

Refine doses/tree size

Assess impacts to other

vegetation

Image: Mike Breiding

Herbicides used to control Eucalyptus

Current Herbicide Recommendations

• DuPont new chemistry

• Non-crop areas

• MoA growth regulator

• Grasses tolerant

• Low volatility & toxicity

• Some woody plants controlled

Aminocyclopyrachlor (AMCP)

1. Determine the rate response of AMCP MAT28-159

compared to Stalker® (imazapyr) and Garlon®

(triclopyr) standards using cut stem or basal bark

treatment on eucalyptus trees.

2. Examine the relationship between stem diameter

and effective AMCP rates for the two application

methods.

3. Determine impacts to non-target eucalyptus trees in

the plantation.

Objectives

ErodedNon-eroded

Eucalyptus benthamii Planted in 2009 at Quincy, FL

• 7 treatments in RCB design with 20 reps at eroded & non-eroded sites

• Applied Nov. 2011; 5 ml mixture per inch basal stem diameter (BSD)

• Herbicide mixed in methylated seed oil carrier (MSO)

• MAT28-159 @ 5, 10, 20, 40% product (1 lb ae AMCP/gal)

• 28% Stalker®(2 lb ae imazapyr/gal)

• 75% Garlon® 4

(4 lb ae triclopyr ester/gal)

• MSO only Check

Image: Wildlands Restoration Team

Treatments in Basal Bark Studies

-20

0

20

40

60

80

100

120

5%AMCP

10%AMCP

20%AMCP

40%AMCP

28%Imaz

75%Triclo

Non-trt

% C

row

n R

ed

uction

Treatment

Eroded site Non-eroded site

Crown Reduction 1 Year After Basal Bark Treatments

a a a a a a ba a a a b b c

Eucalyptus benthamii response to basal bark treatment 2 YAT

Eroded siteMeans in the same circle are not significantly different for height or diameter

0

0

5%

10%

20%

40%

Eucalyptus benthamii response to basal bark treatment 2 YAT

Non-eroded siteTreatment means in the same circle are not significantly different for height or diameter

0

0

5%

10%

20%

40%

• 7 treatments in RCB design with 8 reps at non-eroded site

• Applied Nov. 2011, 1 ml solution per cut, 1 cut per inch BSDiam

• MAT28-159 @ 12.5, 25, 50,100% product (1 lb AMCP/gal)

• 7.8% Stalker®

(2 lb ae imazapyr/gal)

• 50% Garlon® 3A

(3 lb triclopyr amine/gal)

• Non-treated cut check

Image: Wildlands Restoration Team

Treatments in Cut Stem Study

-20

0

20

40

60

80

100

120

12.5%AMCP

25%AMCP

50%AMCP

100%AMCP

7.8%Imaz

50%Triclo

Non-trt

% C

row

n R

eduction

Treatment

Non-eroded

a a a a b a c

site

Crown Reduction 1 Year After

Cut Stem Treatments

Eucalyptus benthamii response to cut stem treatment 2 YAT

Treatment means in the same circle are not significantly different for height

0

0

12.5%

25%

50%

100%

Eucalyptus benthamii response to cut stem treatment 2 YAT

Treatment means in the same circle are not significantly different for diameter

0

0

12.5%

25%

50%

100%

Impacts to non-target trees 2 YATNo significant differences for height or diameter

0

0

Early Results

• Basal bark applications of the lowest AMCP rate tested, 5% in MSO carrier, gave 97-99% eucalyptus crown reduction and generally greater control than the standard 28% Stalker® or 75% Garlon® 4, across all diameter classes at 6 and 12 months.

• Similarly, cut stem applications using the lowest AMCP rate tested, 12.5% AMCP in water, resulted in 100% crown reduction and greater control than 8% Stalker® or 50% Garlon® 3A.

Two-Year Results

• AMCP treated trees by cut stem or basal

bark application did not have any

regrowth by 24 MAT.

• Increases in eucalyptus stem height and

diameter at 24 months suggest that

imazapyr cut stem and triclopyr basal bark

treatment may be impermanent.

• New labeling for AMCP

individual stem treatment

• Future research

– Lower rates of AMCP

– Other tree species

– Continue to evaluate

impacts to other

vegetation

Implications for Management & Future Research

New Forest Vegetation

Management Websitehttp://nfrec.ifas.ufl.edu/Forest_Vegetation_Management/

• Forestry Herbicides

• Wildlife Management

• Prescribed Burning

• Invasive Plants in Forests

• Sources of Assistance for Forest

landowners