Spore Reproduction of Japanese Climbing Fern in Florida as a Function of

Management Timing

Candice M. Prince1, Dr. Gregory E. MacDonald1, Dr.

Kimberly Bohn2, Ashlynn Smith1, and Dr. Mack Thetford1

1University of Florida, 2Pennsylvania State University

Photo Credit: Chris Evans, University of Illinois, Bugwood.org

Old world climbing fern

(Lygodium microphyllum)

Japanese climbing fern

(Lygodium japonicum)

Exotic climbing ferns in Florida

Keith Bradley, Atlas of Florida Vascular Plants Chris Evans, University of Illinois, Bugwood.org

Japanese climbing fern (Lygodium japonicum)

• Native to temperate and tropical Asia

• Climbing habit

• Early 1900s: introduced as an ornamental1

• Long-distance dispersal via wind, pine straw bales2,3

Chris Evans, University of Illinois, Bugwood.org Dennis Teague, U.S. Air Force, Bugwood.org

• Established in 9 southeastern states

• In FL: present throughout the state,

but most invasive in northern areas

• Winter dieback, re-sprouts from

rhizomes1

• Occurs in mesic and temporally

hydric areas1

Distribution

USDA NRCS National Plant Data Team, 2016

Atlas of Florida Vascular Plants, Institute of Systemic

Botany, 2016

Impacts

• Smothers and displaces vegetation,

fire ladders

• Florida Exotic Pest Plant Council:

Category I species

• Florida Noxious Weed List

• Alabama Noxious Weed List (Class

B)

Chris Evans, University of Illinois, Bugwood.org

Chuck Bargeron, University of Georgia, Bugwood.org

Japanese climbing fern: life cycle

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Spore

bank

Gametophyte

stage

Sporophyte

Stage

Development of

fertile frondsSpores disperse

John Tiftickjian,

Delta State University Sigel Lab, University of

Louisiana at Lafayette

Management

• Preventative:

• Constant monitoring of areas

• Remove plants prior to spore formation in the fall

• Spores are easily transported by wind, water,

equipment, and humans

• Avoid intensive management during spore

formation to limit spread

Management

• Biological:

• Naturalized rust fungi (Puccinia lygodii) from South

America will infect plants, but limited in effect

• Insects currently being evaluated for old world

climbing fern

R. Pemberton, USDA-ARS

Management

•Mechanical:

• Hand-pull young plants

• Mowing generally not an option, take care to avoid

spread

• Cutting fronds - regrowth occurs. Pair with chemical

control.

• Fire: limited due to off-target

impacts (fire ladders)

Chuck Bargeron, University of Georgia, Bugwood.org

Management

• Chemical:

• Most effective on new fronds

• Glyphosate

• Metsulfuron

• Best results in fall prior to sporesChris Evans, University of Illinois, Bugwood.org

Previous research

•Herbicide studies to control mature plants:

• Glyphosate, imazapyr, and metsulfuron methyl

• Applications: mid-September in the western Panhandle

• Glyphosate (2% v:v): best control over 2 years

• Observed increased spore production following

herbicide application

Previous research

• Timing of herbicide applications:

• Objective: limit spore development

• Glyphosate and metsulfuron at

4 intervals from July – Sept

• Applications on individual plants

• Metsulfuron: better at limiting

gametophyte development

Current research:

• Two main objectives:

1. Determine if reduced gametophyte development

is similar when applications are made at a broad,

plot-level scale

2. Assess the effect of timing of herbicide

treatments on sites across Florida

• Two year project began in 2015

Western Panhandle sites:

1. Blackwater River State

Forest (BRSF): upland

longleaf pine forest

2. Neal site in Blountstown:

hardwood forest

• Treatments applied to 10 ft.

x 20 ft. plots

Central Florida sites:

1. Ocala National Forest:

upland longleaf pine/sand

pine

2. Lake County: hardwood

forest

• Treatments applied to

fern patches

Herbicide application:

• Herbicide applications via backpack sprayer with a handgun. Plants

sprayed to wet.

Herbicide treatments:

1. Glyphosate – 2% (v/v)

2. Metsulfuron methyl – 0.5 g per liter

3. Glyphosate + metsulfuron methyl

4. Untreated Control

Spore collection:

• Fertile fronds collected 4

weeks after herbicide

treatment

• Spores were separated from

fronds and weighed

• Spore yield = Total Spore Yield

Total FrondWeight

Spore germination and gametophyte development:

• Only BRSF and Ocala

• Spores mixed in water (0.015 g

spores to 20 mL water)

• 4 mL spread over pot surface

• Measured % cover after 5 weeks in

growth chambers:

• 25ºC

• 75% humidity

• 12 hour day

Results:

Results: spore yield

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

July Aug Sept

Spore

Yie

ld (

g/g)

BRSF

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

July Aug Sept

Spore

Yie

ld (

g/g)

NealGlyMetGly+MetControl

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

July Aug Sept

Spore

Yie

ld (

g/g)

Ocala

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

July Aug Sept

Spore

Yie

ld (

g/g)

Lake County

Results: spore yield

• No significant relationship between herbicide treatment

and spore yield, in contrast to previous studies.

• Inconsistencies between sites may be due to:

• Site differences – hardwood sites had relatively

greater shade

• Reproductive biology – reproductive sporangia only

develop on current year’s growth

• Confounding weather events

Results: spore germination and gametophyte development

Blackwater River State Forest Ocala National Forest

Management Implications

• Although previous research suggested metsulfuron

was more effective than glyphosate at limiting spore

production, broadscale applications showed no

differences between herbicides.

• The effect of application timing was location

dependent, although there were significant effects in

mid-September for both sites.

Current work:

• Due to confounding weather events,

replication of field experiments is

needed to re-assess results

• Three sites:

1. Jay, FL (western panhandle)

2. Ocala National Forest (central

Florida)

3. Chito Branch Reserve (south-

central Florida)

Current work:

• Test spore viability directly

• % cover is somewhat subjective

Current work:

• Test spore viability directly

• Developed methodology for

spore germination on

microscope slides

• Measure % germination

instead of % cover

References:

1. Van Loan, A. 2006. Japanese climbing fern: the insidious “other”

Lygodium. Wildland Weeds, Spring 2006: 25-27

2. Lott, M.S., Volin, J.C., Pemberton, R.W., and Austin, D.F. 2003. The

reproductive biology of the invasive ferns Lygodium microphyllum and L.

japonicum (Schizaeaceae): implications for invasive potential. American

Journal of Botany, 90:1144-1152

3. Zeller, M. and Leslie, D. 2004. Japanese climbing fern control trials in

planted pine. Wildland Weeds, Summer 2004: 6-9

Acknowledgements:

• Funding for all studies provided by the Florida Fish and Wildlife

Conservation Commission, Bureau of Invasive Species

Management

• USFS assistance at Ocala National Forest provided by Liz

Ramirez

• Site access at Blounstown provided by Neal Land and Timber Co.

• Field and technical support provided by: Justin McKeithen, Nathan

Mooers, and Heather Van Heuvlen

Thank you! Questions?

Chris Evans, University of Illinois, Bugwood.org