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

Management Timing

Greg MacDonald1, Candice Prince1, Kimberly Bohn2,

Ashlynn Smith1, and 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

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 “From Research in the Panhandle”

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

Spore

bank

Gametophyte

stage

Sporophyte

Stage

Development of

fertile fronds Spores disperse

John Tiftickjian,

Delta State University Sigel Lab, University of

Louisiana at Lafayette

Previous research - Control

• Herbicide studies to control mature plants:

• Glyphosate, imazapyr, and metsulfuron

• Applications targeted during mid-September

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

metsulfuron also very effective

• However, observed increased spore production

following herbicide application

Previous research – Spore Development

• Herbicide Timing:

• Glyphosate and metsulfuron at

4 intervals from July – Sept

• Applications on individual plants

• Metsulfuron: better at limiting

gametophyte development

• Established in 8 southeastern states

• What’s up with Pennsylvania?!

• Present in much of Florida but most

prevalent in northern areas where it

dies back in winter and re-sprouts

from rhizomes

• Continues to move south

Distribution

USDA NRCS National Plant Data Team, 2016

Atlas of Florida Vascular Plants, Institute of Systemic

Botany, 2016

Current research:

• Two main objectives:

1. Determine if reduced gametophyte development

is similar when applications are made at the

landscape level – management scale treatments

2. Assess the effect of timing of herbicide

treatments on sites across Florida

• Two year project began in 2015

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

Western Panhandle sites - 2015

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 - 2015

1. Ocala National Forest:

upland longleaf pine/sand

pine

2. Lake County: hardwood

forest

• Treatments applied to

fern patches

Spore collection:

• Fertile fronds collected 4

weeks after herbicide

treatment

• Spores were separated from

fronds and weighed

• Spore yield = Total Spore Yield

Total Frond Weight

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 - 2015

Spore Yield - 2015

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)

Neal GlyMetGly+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 germination and gametophyte development

Blackwater River State Forest Ocala National Forest

Results 2015

• No significant relationship between herbicide

treatment and spore yield, in contrast to previous

studies.

• Metsulfuron provided much less control on large scale

treatments plots – BRSF

• Very low spore yield in the hardwood shaded sites -

Neal L&T, Lake County, minimal effect of herbicides

• Ocala site – the combination treatment was best

• Spore Germination – impact was seen in the later

application timings with all three herbicide treatments

Spore Germination

• Test spore viability directly

• % cover is somewhat subjective

Changes in Methodology

• Test spore viability directly

• Developed methodology for

spore germination on

microscope slides

• Measure % germination

instead of % cover

Studies - 2016

Florida sites - 2016

1. Blackwater River State

Forest (BRSF): upland

longleaf pine forest

2. Ocala National Forest:

upland longleaf pine/sand

pine

3. Hillsborough County:

hardwood forest

Herbicide application - 2016:

• 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

*Additional herbicide timing

0

5

10

15

20

25

30

35

40

Early July Late July Mid Aug. Early Sep.

Spo

re Y

ield

(m

g/g)

South Florida (Hillsborough)

Gly Met Gly +Met Control

0

10

20

30

40

50

60

70

80

90

100

Early July Late July Mid Aug. Early Sep.

Germ

inat

ion (

%)

South Florida (Hillsborough) Gly Met Gly +Met Control

c

abc abc

bc bc abc abc

ab ab ab

abc

ab

abc abc

abc

a

0

20

40

60

80

100

120

140

Early July Late July Mid Aug. Early Sep.

Spo

re Y

ield

(m

g/g)

Central Florida (Ocala)

Gly Met Gly +Met Control

0

10

20

30

40

50

60

70

80

90

Early July Late July Mid Aug. Early Sep.

Ger

min

atio

n (

%)

Central Florida (Ocala) Gly Met Gly +Met Control

0

10

20

30

40

50

60

70

80

90

100

Early July Late July Mid Aug. Early Sep.

Ger

min

atio

n (

%)

Panhandle (Waren) Gly Met Gly +Met Control

ef

bcde

abc

a

ef

def cdef

abcd

0

20

40

60

80

100

120

Early July Late July Mid Aug. Early Sep.

Spo

re Y

ield

(m

g/g)

Panhandle (Waren) Gly Met Gly +Met Control

RESULTS - 2016

• Hillsborough – low spore yields and minimal effect

of herbicide, no effect on spore germination

• Ocala – low spore yields and minimal herbicide

effects, appears to be some impact of metsulfuron

treatments on spore germination

• Warren – higher spore yields, even as early as July;

some impacts of herbicide on reducing spore yield;

all treatments lowered spore germination

Management Implications

• Although previous research suggested metsulfuron

was more effective than glyphosate at limiting spore

production, broadscale applications showed minimal

differences between herbicides.

• Spore formation occurs earlier than expected,

glyphosate seemed to work best earlier in season,

metsulfuron alone or in combination with glyphosate

for later season applications

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,

SWFWMD – Mike Terry

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

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

Mooers, Ashlyn Smith, and Heather Van Heuvlen

Thank you! Questions?

Chris Evans, University of Illinois, Bugwood.org