Title: TropicLine
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Permanent Link: http://ufdc.ufl.edu/UF00089450/00016
 Material Information
Title: TropicLine
Series Title: TropicLine
Physical Description: Serial
Language: English
Creator: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Ft. Lauderdale, Fla.
Publication Date: March/April 1994
 Record Information
Bibliographic ID: UF00089450
Volume ID: VID00016
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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Tropi cLine Volume 7, Number 2, March-April, 1994

Editor: Alan W. Meerow
Christine T. Stephens, Dean, Cooperative Extension


Fungicide Treatment Affects Seed Germination of

Pygmy Date Palm

Alan W. Meerow
Palm and Tropical Ornamentals Specialist

Palm seeds are sometimes stored for varying periods of time
in polyetheylene bags after the pericarps are cleaned from
the seed. Dusting with fungicide is usually recommended
before they are placed in the bags. Full-strength, wettable
powder formulations of captain
(N-trichloromethyl-thio-3a,4,7,7a-tetrahydrophthalimide) or
thiram (tetramethylthiuram disulfide) are the most common
seed protectants used for this purpose. Seeds of exotic
species received from overseas frequently arrive with a
substantial coating of fungicide, usually captain (pers.
obs.). The purpose of this experiment was to observe any
such affects on the germination of pygmy date palm (Phoenix
roebelenii O'Brien) seeds.

On 10 Oct 1992, 150 freshly cleaned, ripe seed of pygmy date
palm were treated with captain 50% wettable powder (WP),
thiram 75% WP or no fungicide. One hundred grams of each
fungicide was placed in a plastic bag with the seeds and
shaken until the seeds were uniformly coated with the
material. Each treatment consisted of 10 replications of
fifteen seeds. The seeds were sown in small flats of 1:1
(v:v) sphagnum peat moss and perlite and placed on a
greenhouse mist bench (10 sec at 15 min interval) in a
randomized complete block design. Beginning 26 Nov 1992 and
again on 10 and 24 Dec and 7 Jan 1993, the number of
germinated seed in each replication was counted. Emergence
of the cotyledonary petiole more than 0.5 cm from the testa
was the minimum criterion for a seed to be considered
germinated. The experiment was terminated on 7 Jan 1993, and
percent total germination was determined for each sampling
date. Arcsine transformed percentage data and their means
were analyzed for significance with ANOVA and Waller-Duncan


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mean separation tests (SAS Institute, Cary, NC).

Coating pygmy date palm seed with either captain or thiram
had the most significant effects during the first weeks of
germination (Table 1). Controls had much higher germination
percentages that either captan- or thiram-treated seeds on
26 Nov (p = 0.0001), with captain treatment showing the
greatest inhibitory effects. Two weeks later, inhibitory
effects of both fungicides were not significantly different
from each other, but controls were still germinating better
than either treatment (p = 0.0001). By 24 Dec, the
inhibitory effects of the fungicide treatments began to
level off (p = 0.0458), although captan-treated seeds were
still germinating more poorly than controls. At termination,
there was no significant difference between controls and
thiram-treated seeds, but mean final germination percentage
for the captain treatment was significantly lower (p =
0.0249) than either controls or thiram-treated seeds. No
significant block effects were observed at any of the
sampling times (p > 0.63). Necrosis of the cotyledonary
petiole subsequent to germination was also observed among
the captan-treated seeds.

In conclusion, results with pygmy date palm seed indicate
that direct contact of palm seed with full-strength seed
protectant fungicides may inhibit germination. While both
thiram and captain reduced the initial rate of germination,
only captain significantly reduced total germination
percentage.

Table 1. Effects of captain and thiram treatment on germination of pygmy date palm seed.

o0 Geinunation
Treatment No\ 21) Dec 10 Dec 24 Jain
Control 34.0az 67.3a 77.3a 79.3a
C(aptaln ic 24 54 ) 5S -b
Thiram 12.0b 38.7b 66.7ab 76.0a


ZMean separations within columns by the Waller-Duncan k-ratio method (k=100) on arcsine transformed
percentage data. Means followed by the same letter are not significantly different.



Catclaw Mimosa in Florida


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David L. Sutton, Professor
Aquatic Plants

Kenneth A. Langeland, Associate Professor
Aquatic Plant Center, Gainesville

Robert L. Kipker, Biological Administrator I
Florida Department of Natural Resources, Tallahassee

Catclaw mimosa (Mimosa pigra L.), a native of Central America,
was introduced in Florida probably through the ornamental
plant nursery industry in the early 1950's. Catclaw mimosa,
or giant sensitive plant as it is also sometimes called, is
unique in that its leaves close (fold together) rather
quickly when touched, exhibiting an animal-like response
that is a novelty among plants. For this reason, catclaw
mimosa has been introduced in many countries as a botanical
curiosity.

Catclaw seeds are covered with hooked hairs which allows
seeds to attach to moving objects. No direct evidence is
available to suggest the manner in which catclaw mimosa was
introduced in Florida. However, its presence near old
ornamental plant nurseries in the Jupiter and Avon Park
areas suggest catclaw mimosa was introduced as a novelty
plant.


Distinguishing Field Characteristics

Distinctive field characteristics of catclaw mimosa include:
sensitive, evenly bipinnately compound leaves, recurved
thorns on the stem, petiole, and leaf rachis; straight
spines at the junction of leaflets, pink flowers arranged in
a head and extended on a stalk from the stem, clusters
(hands) of flat brown pods (fingers) each with transverse
sections held by sutures, and single seeded sections of the
pod with golden hairs scattered on the surface which break
from the fingers, leaving an empty frame.


Seed Germination and Growth

Mature catclaw mimosa seeds which drop from the fingers can
float for a period of time. While seeds may travel with
water currents, infestations in Florida are more likely to
experience inundation rather than actual flowing water. This
lack of contact with flowing water probably has reduced wide


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spread dispersal of catclaw mimosa as compared to other
countries. In Florida, seedlings most often occur directly
under the parent plant.

Although we have found that catclaw mimosa seeds will
germinate underwater and produce one set of true leaves,
they will not continue growth unless emersed. In Australia,
seeds have been found to float for a month, but in our
studies, we have found that seeds will sink within 10 days
of being placed on the surface of water. If catclaw mimosa
plants were to gain access to the Everglades, then water in
this wetland system would provide a major opportunity for
dispersal of seeds. The wet and dry hydrologic cycle in
south Florida may provide ideal conditions for germination
of catclaw mimosa seeds and subsequent growth.

Catclaw mimosa produces seeds year round in the tropics and
in Florida. A mature plant may produce 42,000 or more seeds
a year, although in Florida, annual seed production per
plant is probably much less due to poor soil fertility and
heavy plant competition. Also, it appears that flowering and
seed set are inhibited by shading.

Catclaw mimosa plants in Florida contain on average 4.5
fingers per inflorescence and 19.1 seeds per finger. A well
fertilized plant in a Broward County golf course site had
one hand with a cluster of 34 fingers. Ripe seeds develop
within about 5 weeks of flowering. Seeds remain viable for
many years, but young seeds have a higher germination rate
than older seeds.

Once established, catclaw mimosa can withstand almost total
submergence by readily forming adventitious roots and corky
tissue along its stems. Plants grow best on well fertilized,
disturbed sites in full sun. In infested areas, catclaw
mimosa are causing problems by growing mixed with crop
plants.


Known Locations of Catclaw Mimosa in Florida

As of 1993, catclaw mimosa plants have been identified
growing in Broward, Palm Beach, Martin, St. Lucie, and
Highlands Counties in Florida. All the plants on the St.
Lucie River and a Broward County golf course are under
control. Catclaw mimosa plants growing in Palm Beach,
Martin, and Highlands County are the most persistent and


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entrenched.

Although large populations of catclaw mimosa are not present
in Florida, the plant poses a serious threat to the
Everglades wetland ecosystem. The formation of adventitious
roots and corky tissue along stems of flooded plants may
allow catclaw mimosa to colonize wetland areas in south
Florida at the expense of native aquatic plants as
experienced in other countries.

Control of Catclaw Mimosa with Herbicides

Foliar applications of herbicides are generally the most
effective method for controlling catclaw mimosa. Repeat
treatments are usually necessary because of the sprawling
growth habit of these plants which makes it difficult to
obtain complete coverage of the herbicide.

Catclaw mimosa usually starts growth in the under story of a
plant thicket, then grows to the top and spreads out in the
sunlight. This competing vegetation interferes with survey
and herbicide application efforts.

Studies with herbicides at label rates in south Florida have
shown that soil applications of Spike 40P (tebuthiuron), and
foliar applications of Transline (clopyralid), a broadleaf
specific herbicide, will provide excellent control of
catclaw mimosa. One advantage of using Transline is that it
kills only catclaw mimosa and does not affect most
surrounding plants. In many situations catclaw mimosa grows
entwined with other plants making it difficult to spray the
catclaw mimosa without getting herbicide on non-target
plants. Transline is not currently registered in Florida but
we are in the process of applying for a Special Local Need
Registration (24C) permit.

Since most seedlings have been found to germinate under the
parent plant, soil treatments with Spike in the seed fall
area will probably affect most of the dropped seeds. Land
use in most infested locations, however, prevents use of
Spike because this herbicide is soil active and kills a
broad spectrum of plants.

Foliar applications at label rates for Rodeo (glyphosate),
Garlon 3A (triclopyr), and Banval 720 (dicamba) generally
require repeat applications to ensure complete kill of


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catclaw mimosa plants. Small plants are more easily killed
than large plants.


Control of Catclaw Mimosa with Other Methods

Manual cutting or burning, or a combination of these
methods, will temporarily control the spread of catclaw
mimosa but rapid regrowth reduces the effectiveness of these
methods. Furthermore, incomplete burning tends to stimulate
seed germination and new plants will readily sprout from cut
stumps. Young seedlings may be removed by pulling.

Biological controls with plant pathogens and insects are
being researched in other countries, but are not presently
available for use in Florida.

Several legume feeding insects have been found on catclaw
mimosa in Florida. The extent to which these insects affect
growth of the plants is unknown. However, we have noticed
feeding activity by several insects on seeds which may
reduce the seeds' viability and number available to
germinate.


Eradication of Catclaw Mimosa

Eradication of catclaw mimosa in Florida appears to be an
attainable goal. Since known populations in Florida are low
in number of plants, an eradication program consisting of
(1) surveying for new plants, (2) removal of flowers and
seeds from mature plants, (3) application of herbicides to
all existing plants, and where applicable, hand pulling to
remove seedlings and young plants, and (4) monthly surveys
to ensure no growth of seedlings is one approach to ensure
no new catclaw plants will survive.

An important part of the eradication program is to inform
the public of the dangers of catclaw mimosa to help find
isolated plants that may have been planted for their
botanical curiosity.

Herbicides are the most practical method to eradicate
catclaw mimosa plants in Florida. Based on ecological
studies and herbicide trials, and the number of known
infestations, a two-person team working full time surveying
and spraying every site once a month should be adequate to
eradicate this plant in Florida. A year-round once-a-month


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schedule is required because catclaw mimosa plants have been
found to flower all year, and only about 5 weeks are
required from flowering to seed set. Surveying and spraying
will need to continue until the seed bank is depleted,
approximately 10 years. Successful completion of this
eradication program will eliminate the threat of catclaw
mimosa becoming a major weed problem in Florida.


Reporting Catclaw Mimosa Plants

Any person who suspects catclaw mimosa may be growing in
Florida needs to contact: DNR Regional Biologist for south
Florida, (407/793-5666); University of Florida, IFAS, Center
for Aquatic Plants (904/392-9613); Fort Lauderdale REC
(305/475-8990); or DNR, Tallahassee (904/488-5631) so the
plants can be identified and destroyed if found to be
catclaw mimosa.


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