Title: TropicLine
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Permanent Link: http://ufdc.ufl.edu/UF00089450/00007
 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: November/December 1993
 Record Information
Bibliographic ID: UF00089450
Volume ID: VID00007
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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Trop cL ine Volume 6, Number 6, November-December, 1993

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


Effectiveness of Two Biorational Substances (Neem

and Abamectini Against Citrus Leaf Miner

F. W. Howard

Associate Professor of Entomology

In southeastern Florida, citrus trees serve both as fruit
trees and ornamentals. Recently, I tested two biorationals,
azadirachtin and abamectin, both of which are essentially
non-toxic to mammals, for effectiveness against the citrus
leaf miner [Phyllocnistis citrella Stainton (Lepidoptera:
Gracillariidae)], a pest that is native to Asia and new to
Florida.


Materials and Methods

Seedlings of sweet lime (Citrus limettioides Tanaka) were
kindly supplied to us by Charles Youtsey of the Florida
Department of Agriculture and Consumers Services, Winter
Haven. These were about 0.3 m tall and with about 30 leaves
each, growing in a medium of equal parts of muck, sharp and
and cypress sawdust in 15 cm dia plastic containers. They
were initially kept in a screen cage to protect them from
attack by citrus leaf miner. Each plant was fertilized on
September 1, 1993, with a soil application of 5 g 18N-6P-8K
Osmocote and removed from the cage and placed near an orange
tree [C. sinensis (L.) Osbeck] infested with citrus leaf
miner.

Twelve plants each were assigned at random to either of 2
different treatments or an untreated control. The treatments
were: (1) Avid (abamectin 0.15 EC)(MSD Agvet, Merck & Co.,
Rahway, New Jersey) at 0.312 ml / 1 H20 (4 fl.oz. / 100
gal.), (2) Azatin (Agridyne Technologies, Inc., Salt Lake
City, Utah) at 2 ml / 1 H20 (60 ppm azadirachtin) + 0.5 ml /


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1 H20 Triton B-1956 spreader-sticker (Rhom & Haas Co.,
Philadelphia, PA). The treatments were applied weekly for 4
weeks beginning September 9. Upper and lower leaf surfaces
were sprayed to run-off using a 2-liter handsprayer.

Plants were examined for leaf miners on September 17 (one
week after the first spraying) and weekly thereafter for
four weeks. The number of leaves with mines per plant was
determined. For comparing the treatments, only the leaves
with well-developed mines and which were curled due to the
leaf miner damage were counted. Mines in initial stages that
did not cause significant damage or curling of leaves were
noted separately. Numbers of leaves with advanced mines per
plant were transformed with the x + 0.5 transformation
before analysis by ANOVA and the means tested for
significance with the Waller Duncan t-test.

At the end of the four week period, leaves with mines were
removed from the plants and examined under the microscope to
determine the fate of leaf miners in the different treatment
groups.


Results

Citrus leaf miner damage was observed on newly flushed
leaves, but not on hardened-off leaves. About 50 % of the
plants in each treatment group and the control flushed
during the 4-week period of the experiment and thus were
susceptible to attack by leaf miners. During this period,
leaf miners did not complete mines in leaves of the plants
treated with Avid or Azatin. By comparison, at the end of
the 4-week period, 58.3 % of the plants in the control group
had well-developed leaf miner damage accompanied by leaf
curl. There was a mean of 2.84 leaves with well-developed
mines per plant in the control compared to 0 leaves with
well-developed mines in the Avid- and Azatin-treated group
(P < 0.05).

Examination in the laboratory of leaves from plants in the
control group revealed several empty pupal cases rolled in
leaf edges, indicating that leaf miners had completed
development to adult. Some late instar larvae were also
seen.

The plants treated with Avid remained completely free of


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leaf miner damage. By October 1, 33 % of the plants treated
with Azatin had 1 to 7 incipient mines. By October 8, 50 %
of the Azatin-treated plants had incipient mines, and the
incipient mines observed on October 8 had not progressed.
These mines were observed again on October 15 and had not
progressed and there was no leaf curl. Thus, although leaf
miners initiated mines in the leaves, the Azatin treatment
protected the leaves from being damaged significantly.

These results indicate that the 2 biorationals tested
prevent damage by citrus leaf miners when sprayed on leaves
prior to oviposition by this insect. Thus sprays must be
timed just as trees are flushing, which may be expected to
be different for different species and varieties of citrus
and, as in the case of our test plants, for different
individual plants. Further information is needed to
determine the minimum effective dosage, maximum intervals
between applications, and other parameters. Alternating
treatments with azadirachtin and abamectin and possibly
other compounds in the interest of insect resistance
management needs to be investigated, as well as the
potential effect of these compounds on beneficial insects.

Azadirachtin and abamectin products are potentially useful
for controlling citrus leaf miner.



Water-lilies of Florida

David L. Sutton

Professor, Aquatic Plants

Introduction

The Nymphaeaceae or water-lily family contains the genera
Nymphaea, commonly called water-lilies, and Nuphar, commonly
called spatter-docks or yellow cow-lilies. Members of this
family occur from tropical to northern cold temperate
regions of the world. Many water-lilies produce large, showy
flowers that make them attractive and sought after plants as
compared to the spatter-docks.

Water-lilies grow best in full sunlight in static water
protected from wind and wave action, whereas the
spatter-docks will tolerate wind and water flow. The


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floating leaves of water-lilies, although attached to the
rhizome by long, trailing, flexible petioles, are damaged by
the pounding action of wind and waves. Leaves of
spatter-dock are held above the surface of the water on
stiff, erect petioles, and thus are not influenced as much
by wind and waves.

Water-lilies, because of their large, showy and sometimes
fragrant flowers, are favorite aquatic plants for use in
ornamental pools and ponds. Modern-day interest in
water-lilies is said to have begun in 1786 with the
introduction to England of fragrant white water-lilies from
North America for use as ornamental aquatic plants.

There are about 35 species of water-lilies worldwide. Many
water-lily hybrids have been produced for ornamental
purposes. A few hybrids have naturalized from cultivation
but none are known to cause problems. Water-lilies in
Florida include both native, e.g., Fragrant white
water-lily, and introduced species, e.g., Cape Blue
water-lily; naturalized hybrids, e.g., Dauben water-lily;
and one natural hybrid, Sulphur water-lily.

Native

Fragrant White Water-lily (Nymphaea odorata Ait.)

Fragrant white
water-lily
plants are the
ost abundant of
all the
water-lilies in
li or th America
ar cl they occur
fro-m Canada to
Iicaragua. Two
varieties occur
in Florida.
variety gigantea
Tricker has
large flowers
and medium to large leaves and occurs through out much of
Florida. Variety godfreyi Ward has small flowers and small
to medium leaves and occurs primarily in West Florida.
Several other varieties of fragrant white water-lily occur


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in other areas of North America.


Yellow Water-lily (Nymphaea mexicana Zucc.)

Yellow water-lilies occur in Florida, along the southeast
coast of the US into Texas and Arizona, and in Mexico.
Yellow water-lilies were abundant in many shallow water
areas in Florida before the introduction of water hyacinth
(Eichhornia crassipes). Yellow water-lilies have been
crowded out by the aggressive floating waterhyacinth plants.
Now that maintenance control of waterhyacinth plants has
been achieved in many lakes such as in Lake Okeechobee and
the Kissimmee Chain, yellow water-lilies are much more
common than they were a few years ago.

Flowers of yellow water-lilies extend above the surface of
the water on a stout peduncle. The yellow petals open around
noon and close about 4 PM in the afternoon. Upper surfaces
of leaves tend to be bright green in the summer and
greenish-purple in the winter.

Sulphur Water-lily (Nymphaea x thiona Ward)

This plant is a natural hybrid of the yellow water-lily and
variety gigantea of the fragrant white water-lily, and may
be found where both parents grow close to each other. Its
flowers are quite large like the fragrant white water-lily
with light yellow petals on inflorescences that extend above
the surface of the water like the yellow water-lily. The
Sulphur water-lily appears to be sterile since viable seeds
have never been collected.

The Sulphur water-lily was first described in 1957 from
plants collected in the St. Johns River. A horticultural
hybrid was developed a number of years ago but this hybrid
is probably the result of the cross between the yellow
water-lily and the fragrant white water-lily variety
odorata.

Lloyd Mitchum, 11 to 12 years ago, observed the Sulphur
water-lily in areas between Indian Prairie Canal and Dykes
Ditch on Lake Okeechobee. Within the last few years however,
this plant has been found in several areas south of the
Monkey Box on Lake Okeechobee. The apparent expansion of the
Sulphur water-lily again suggests that maintenance control


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of water hyacinth is allowing re-establishment and growth of
native aquatic plants.

Everglades Water-lily (Nymphaea elegans Hook.)

The Everglades water-lily is found in shallow water areas
primarily in the south to southwestern portions of Florida.
It flowers from August to November. The flower consists of
small pale blue to almost white petals. The petals always
have a bluish tinge that deepens on drying.

Naturalized

Cape Blue Water-lily (Nymphaea capensis Thunb.)

Cape Blue Water-lilies are native to South Africa. As its
name indicates, the flowers contain blue to lavender petals
that are whitish at the base. This plant has many
horticultural variations, and the plants in Florida may be
variety zanzibariensis (Casp.) Conard.


Dauben Water-lily (Nymphaea x daubeniana)

The Dauben water-lily is a horticultural hybrid that has
naturalized in a few areas of Florida. Its leaf blades are
usually green on both surfaces. The upper leaf surface
contains a mound of fibrous tissue at a point above the
juncture of the blade and petiole from which epiphyllous
plantlets form. These plantlets may be used to propagate new
plants. Petals of Dauben water-lilies are light blue and may
be confused with other blue water-lilies.

Sleeping-beauty Water-lily (Nymphaea blanda G. F. W.
Meyer) and N. jamesoniana Planch.

These two species are rare in Florida. Although they belong
to a large South American group of night blooming
water-lilies, they probably are native to Florida. They
occur primarily in the west central areas of Florida.
Because they bloom at night, they are easily overlooked.
These water-lilies produce white flowers from September to
November.

Nymphaea ampla (Salisb.) DC.


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This water-lily, native to tropical America, has naturalized
in areas of Lee County. The plant has flowers with white
petals that extend above the surface of the water.

Management of Water-lilies

Water-lily plants are not generally considered to be problem
aquatic plants. However, at times they may present problems
in localized areas of a body of water or in small ponds.
Foliar applications of glyphosate products registered for
use in aquatic sites at label rates will provide adequate
control of problems resulting from excessive growth of
water-lily plants. With careful applications, a desirable
level of plants can be maintained.


References

Godfrey, R. K. and J. W. Wooten. 1981. Aquatic and Wetland
Plants of Southeastern United States: Dicotyledons. The
University of Georgia Press, Athens. 933 pp.

Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular
Plants. St. Martins Press. NY. 610 pp.

Ward, D. B. 1977. Keys to the Flora of Florida -- 4,
Nymphaea (Nymphaeaceae). Phytologia 37(5) :443-448.

Zomlefer, W. B. 1989. Flowering Plants of Florida A Guide
to Common Families. Biological Illustration, Inc.
Gainesville, FL. 207 pp.

Aquatic plant images provided by the Information Office of the University of Florida, IFAS, Center for
Aquatic Plants (Gainesville).


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