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Group Title: Bulletin
Title: Gardenias in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00094963/00001
 Material Information
Title: Gardenias in Florida
Series Title: Bulletin - Florida Agricultural Extension Service ; 145
Physical Description: 16 p. : ill. ; 23 cm.
Language: English
Creator: Watkins, John V. ( John Vertrees )
University of Florida -- Agricultural Extension Service
Publisher: Agricultural Extension Service, University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1950
Copyright Date: 1950
 Subjects
Subject: Gardenia -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
General Note: Cover title.
General Note: "August, 1950."
Statement of Responsibility: by John V. Watkins.
 Record Information
Bibliographic ID: UF00094963
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 84169498

Table of Contents
    Front Cover
        Page 1
    Front Matter
        Page 2
    Main
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
Full Text
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COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
AGRICULTURAL EXTENSION SERVICE, UNIVERSITY OF FLORIDA
FLORIDA STATE UNIVERSITY
AND UNITED STATES DEPARTMENT OF AGRICULTURE
COOPERATING
H. G. CLAYTON, DIRECTOR
BOARD OF CONTROL
Frank M. Harris, Chairman George J. White, Sr., Mt. Dora
St. Petersburg Eli H. Fink, Jacksonville
Hollis Rinehart, Miami W. F. Powers, Secretary
N. B. Jordan, Quincy Tallahassee
STAFF, AGRICULTURAL EXTENSION SERVICE
J. Hillis Miller, Ph.D., President of the University I
J. Wayne Reitz, Ph.D., Provost for Agriculture 1
H. G. Clayton, M.S.A., Director of Extension
Marshall O. Watkins, M. Agr., Assistant Director
Agricultural Demonstration Work, Gainesville
J. Francis Cooper, M.S.A., Editor1
Clyde Beale, A.B.J., Associate Editor'
J. N. Joiner, B.S.A., Assistant Editor
J. Lee Smith, District Agent
K. S. McMullen, B.S.A., District Agent
F. S. Perry, B.S.A., District Agent
H. S. McLendon, B.A., Soil Conservationist
R. S. Dennis, B.S.A., Executive Officer, P. & M. Admin.2
C. W. Reaves, B.S.A., Dairy Husbandman
N. R. Mehrhof, M. Agr., Poultry Husbandman
J. S. Moore, M.S.A., Poultryman
A. W. O'Steen, B.S.A., Supervisor Egg-Laying Test, Chipley
O. F. Goen, D.V.M., Animal Husbandman
James A. McGregor, B.S., Assistant Animal Industrialist
L. T. Nieland, Farm Forester
H. G. Hamilton, Ph.D., Agricultural Economist 1
Charles M. Hampson, M.S., Agricultural Economist, Farm Management'
D. E. Timmons, M.S.A., Economist in Marketing
F. W. Parvin, B.S.A., Associate Economist
John M. Johnson, B.S.A., Agricultural Engineer
Fred P. Lawrence, B.S.A., Citriculturist
W. W. Brown, B.S.A., Boys' 4-H Club Agent
Joe N. Busby, B.S.A., Assistant Boys' 4-H Club Agent
A. M. Pettis, B.S.A., Farm Electrification Specialist2
John D. Haynie, B.S.A. Apiculturist
V. L. Johnson, Rodent Control Specialist 2
J. Russell Henderson, M.S.A., Agronomist 1
F. S. Jamison, Ph.D., Vegetable Crops Specialist 1
Stanley E. Rosenberger, M. Agr., Asst. Veg. Crops Specialist
Forrest E. Myers, M. Agr., Assistant Veg. Crops Specialist
Home Demonstration Work, Tallahassee
Mary E. Keown, M.S., State Agent
Ethyl Holloway, B.S., District Agent
Mrs. Edyth Y. Barrus, B.S.H.E., District Agent
Anna Mae Sikes, M.S., District Agent
Joyce Bevis, A.M., Clothing Specialist
Mrs. Bonnie J. Carter, B.S., Home Improvement Specialist
Grace I. Neely, M.S., Asso. Economist in Food Conservation
Mrs. Gladys Kendall, A.B., Home Industries and Marketing Specialist
Lorene Stevens, B.S., 4-H Club Specialist for Girls
Ruth Lemmon, B.S.H.E., Asst. Girls' 4-H Club Agent
Negro Extension Work, Tallahassee
Floy Britt, B.S.H.E., Negro District Agent
J. A. Gresham, B.S.A., Negro District Agent
Cooperative, other divisions, U. of F.
2 In cooperation with U. S.








Gardenias in Florida


By JOHN V. WATKINS
Associate Professor, Horticulture, University of Florida

Ranking with the camellia, rose and hibiscus, the gardenia has
long been a favorite dooryard shrub in the South. Usually grown
as a free-standing specimen, this beautiful broadleaved ever-
green is much planted by urban and rural homeowners alike.
A member of the Rubiaceae family, the genus Gardenia was
named after Dr. Alexander Garden, a physician in Charleston,
South Carolina, during colonial days. While botanists place 60
species of subtropical plants of the Eastern Hemisphere within
this genus, only two are prominent in American horticulture.
Gardenia jasminoides Ellis', from China, is the species to which
belong all forms-those available as cut flowers in retail shops
and those obtainable as landscape shrubs in nurseries and chain
stores. "Capejasmine" of anti-bellum days, the old vernacular
name, is quite rapidly losing ground and today the shrub, like the
ever-popular corsage-flower that it produces, is called "gardenia."
A second species, Gardenia thunbergia', is important because
it is used as a rootstock for out-door gardenias in southern Flor-
ida. Named for C. P. Thunberg, the 18th century Swedish
botanist, this robust shrub from South Africa resists attack of
the root-knot nematode and tolerates hot, inorganic sands.
The crape-jasmine (Ervatamia coronarium) and Grand Duke
jasmine (Jasminum sambac) are not true gardenias.

Choose Good Location
In its natural habitat in China the gardenia grows in a deep
fertile soil that is slightly acid in reaction, retentive of moisture
and well supplied with organic matter. Long sunny days, ap-
proximately 150 inches of rain annually and freedom from ex-
tremely low temperatures are also characteristic of its native
environment. Some of these factors are fulfilled, and all, upon
occasion, are present in the Southeastern States, and here the
gardenia has found a congenial home.
When these climatic factors exist, gardenias may be set di-
rectly into garden soil. When one or another is lacking, the gar-

Manual of Cultivated Plants, Revised Edition, L. H. Bailey, Macmil-
lan, 1949.






Florida Agricultural Experiment Station


dener must supply the lack. If the soil is light and sandy, it
should be removed from the planting site and replaced with an
acid, composted mixture of peat, leaf-mold and manure. The pH
may be reduced one point, say from 6.5 to 5.5, by the addition of
3 pounds of aluminum sulphate to 50 cubic feet of compost. In
order that there shall be no shortage of any mineral, a commer-
cial fertilizer known to contain minor elements, or a mineral
supplement mixture, should be sprinkled in lightly as the planting
site is being prepared. Your seedsman will help you select one of
these and advise you as to the quantity to use.
If it is feasible to treat the gardenia plot with a soil fumigant
well in advance of planting it is an excellent plan to do this.
Garden supply houses stock several chemicals that will kill nema-
todes and other soil-borne troubles. Patented applicators can be
rented when the chemical is bought.
A location in full sun well away from trees or large shrubs is
recommended. The north side of a tall building is not the best
location because of the absence of sunlight there, nor is the south
wall of a building a good location because of the excessive heat of
summertime and the large amount of water-loss to the sun.
The light, shifting shade cast by tall pine trees is good for
gardenias and the fallen needles make an excellent mulch. Open-
headed turkey oaks and tall palms cast mild shade in which
gardenias grow well.
Gardenias thrive on lake banks if the water level is constant.
The plants will be killed, however, by inundation.
A heavy mulch, four to six inches deep, of oak leaves, pine
straw, tobacco stems, cane bagasse, peanut hulls or other organic
material will be reflected in vigorous growth and heavy flowering.
Cultivation should be unnecessary under this system. In large
nurseries where gardenias are propagated on heavy fertile soil,
clean cultivation is used.
Watering during dry spells is necessary to the health of the
plants. Allow the hose to run for about two hours, once every
seven to 10 days during the dry periods of November and April.
This latter season is critical, as acute drought at this time may
cause severe bud drop. A moist soil is a requisite for success
with gardenias, yet low humidity during the flowering period
is desirable.
Pruning is accomplished when the blossoms are cut in spring-
time. Usually no other use of shears is necessary. Young plants,







Gardenias in Florida


Fig. 1.-The gardenia is a favorite dooryard shrub of long standing in
the South.












SF






Florida Agricultural Experiment Station


growing vigorously during their first year, may be pinched once
in June and again in August to encourage heavy branching.

Varieties
Gardenia jasiminoides displays a marked tendency to break
into abnormal (aberrant) forms by mutation. The score or
more of clones 2 known in American horticulture have arisen as
bud sports. These present-day gardenias, and others to arise
in future, are known as cultigens and are given distinctive names
(Belmont, Hadley, Mystery, Miami Supreme) by their origina-
tors. They are always increased asexually.
The first gardenia to be grown as a named type was Veitchii.
This small-flowered, dwarf-growing gardenia, introduced by the
well known English firm, James Veitch and Son, filled a long-felt
want, as it could be flowered in mid-winter.
Since the thirties several other new and distinctive gardenias
have been introduced in the trade. There follow descriptions of
all patented gardenias briefed from descriptions furnished by
the United States Patent Office.
Hadley, a leading commercial variety, has black-green foliage,
is a vigorous grower that produces large, flat blossoms in spring.
Mystery is grown as a greenhouse gardenia and very widely
as a garden shrub in Florida. The foliage is not as dark as that
of the preceding variety and is distinctly pointed. The blossoms,
produced in April-May out of doors, have short calyxes and
usually open quickly to display the anthers in the center.
Belmont, Plant Patent 93, April 17, 1934. A new and distinct
variety of gardenia, a vigorous grower that bears flowers of
extraordinary size (4-5 inches across) and quality at all seasons
of the year. This clone arose as a sport in a greenhouse in
Belmont, Massachusetts, in 1926.
Plant Patent 364, February 27, 1940. Originated as a
seedling resulting from a cross of California Grandiflora x
Mystery. This is said to be more vigorous than either parent,
produces large flat blossoms that have a distinct, tight, central
whorl. The flowers are said to be superior in keeping quality.
Miami Supreme, Plant Patent 622, April 4, 1944. A new and
distinct variety which arose as a sport of Veitchii in Miami,
Florida. The large blossoms (4-6 inches in diameter) are said

2 A clone is a group of identical plants, propagated vegetatively, that
arose from a single bud. Examples are Hamlin orange, Better Times rose
and Miami Supreme gardenia.






Gardenias in Florida


to resist bruising which makes it a good shipper. The flower has
a desirable camellia-form with a central whorl, has more than
25 petals which require 7-10 days to open.
Plant Patent 654, March 13, 1945. A new and distinct gar-
denia which arose as a seedling that resulted from self-pollination
of "grandiflora" by a nurseryman in Honolulu. The blossoms
(4 inches across) are flat, with the desired central whorl which
covers the anthers and contains 36 petals. Good keeping quality
and resistance to bruising are claimed by the originator.

Propagation

In Northern Florida and in other sections, when plants are to
be grown in containers up off the ground, cuttage is the method
used to increase gardenias. Tip cuttings some four or five
inches in length are taken from disease-free plants from Decem-
ber to March. The slips must be firm but not hard and woody,
as the latter type roots very poorly as a rule.
As high humidity, constant temperature and constant moisture
are necessary for speedy rooting, a closed case with a glass top
is desirable. This may be simply a wooden box with a pane of
glass over the top, or it may be a well-constructed propagating
case with hinged lid and electric cable bottom heat (see Fla. Agr.
Extension Service Bulletin 137). In each case some device must
be employed to break the direct rays of the sun, lest the tempera-
ture rise to dangerous levels.
The medium used in rooting gardenia cuttings may be clean,
sharp builder's sand, peat or sphagnum moss. Because of
gardenia's susceptibility to root-knot and diseases, sterilized or
absolutely fresh material is required.
One of the proprietary rooting aids may be used just before
the cuttings are inserted. While chemical aid is not essential,
larger root systems are formed in shorter periods on cuttings
that have been dipped in one of the root-inducing powders.
The leaves should be moistened daily with a very light mist.
For the first week newspapers or muslin should reduce the light.
After that the light is gradually increased. It has been proved
many times that leafy cuttings root more rapidly when they
are subjected to abundant light.
After a week or 10 days, open the case during the humid
hours of early morning and gradually increase the ventilation






Florida Agricultural Experiment Station


during the remaining three weeks that the cuttings remain in
the propagating case.
After a month the roots should be sufficiently numerous to
maintain the young plants. Then the plantlets are carefully
lifted and set into three-inch clay pots or into raised beds. The
growing medium may be a composted mixture of peat, leaf-mold
and soil. An open, well-aerated growing medium is necessary
for optimum development. A compact, heavy or water-logged
soil will cause the roots to die and the plant to deteriorate rapidly.
After the rooted cuttings are potted they are plunged in a bed
of cypress sawdust or peat, soaked heavily and protected from
sun and wind by muslin or a temporary glass case. Gradually
the plants are subjected to more and more light and air until,
after 10 days, they are protected by slat half-shade only.

Fig. 2.-Flowers of the Miami Supreme gardenia. Left, bud; next,
bud just opening; third, flower three days old; right, flower one week old.
(Permission by plant patent owner, Comte Nursery & Florist. Trade
Mark-Miami Supreme.)














".; PIN






Gardenias in Florida


Propagation By Graftage
For garden culture in southern Florida grafted gardenias are
preferred. Potted seedlings of Gardenia thunbergia, about
pencil thickness, are grafted by the side-graft, splice-graft or
whip-graft method.
In the side-graft a deep, sloping cut is made in one side of the
understock plant about six or eight inches above the pot. A
terminal cion with two to four leaves about three inches long is
sharpened to a long sloping wedge that will fit into this slot.
Cambiums on one side are carefully aligned, the work is bound
with a rubber budding strip, then carefully waxed to exclude air
and water. The newly grafted plants are carried in a glass-
topped, closed grafting case. After 10 days ventilation is given
and gradually increased each day until the case is left open,
except during the arid hours of mid-day. When the cion has
grown a few inches the top of the Gardenia thunbergia is care-
fully pruned away just above the successful graft union. The
rubber budding strip will have disintegrated by this time.







Florida Agricultural Experiment Station


In the splice-graft the entire top of a potted Gardenia thun-
bergia is removed with a long sloping cut. A cion is cut similarly
and, after cambiums on one side are matched, the work is
wrapped with cotton cord. Waxing and carrying the plants in
a closed grafting case to assure high humidity are recommended.
The cord should be cut during the second week.
With the whip- or tongue-graft method the approach is the
same as for the splice-graft. A tongue is cut by making an inci-
sion across the grain on the slope of both the understock and the
cion. The two are fitted together so the tongues interlock. Bind-
ing with cord and waxing finishes the job. This is the most diffi-
cult of the three methods.
Prior to World War II seeds of Gardenia thunbergia were im-
ported from Japan but today Florida growers are dependent
upon domestic seed supplies. Seeds and small seedlings are
indeed most difficult to come by.
Terminal cuttings of this tropical shrub will root, but usually
three to six months are required for the development of adequate
root systems.

Cutting the Blossoms
The buds are cut when white first begins to show as the petals
unfurl. Then they are placed in cold water and held under
refrigeration so that the petals unfurl slowly, allowing the cen-
tral whorl to give the flower a heart and cover the anthers. In
the warmth of Florida's springtime climate the petals fold back
quickly to expose the anthers. Yellow edged, these turn black
all too soon and the usefulness of the gardenia is at an end.
Nothing can be done about this undesirable condition, yet it is
claimed that some of the patented varieties hold the raised cen-
tral whorl better than older types. The open flower must be of
pure, unblemished white, with no yellow or green.
Gardenias have a wide variety of floral uses. For table decora-
tions, breakfast trays, for hospital arrangements they are superb,
but they reach their pinnacle of perfection as corsage flowers.

Pot Culture
In sections where the soil is of poor quality, of alkaline reac-
tion, or infested by root-knot nematodes, it may be desirable to
grow gardenias permanently in containers. From the three-inch






Gardenias in Florida


clay pots into which the rooted cuttings were set the plants can be
shifted over into five-inch or six-inch containers for six or eight
weeks, or they may be set in their permanent vessels. These may
be boxes of cypress, pots, urns, jardinieres or cans. Vessels 12
to 15 inches across should be large enough to support mature
flowering gardenias. Holes for drainage must be in the bottom
to allow the free passage of water, and an inch of neutral silica
gravel or broken flower pots should cover the bottom. The grow-
ing medium may be the same acid composted mixture of peat,
cow manure and soil. Because of the prevalence of root-knot
nematodes and soil-borne diseases, gardenia soil should be
sterilized by heating to about 1600 F. for three or four hours.
The containers should be placed upon an off-the-ground support
so that infected soil particles will not splash in from the earth.
Gardenias require regular applications of balanced fertilizer
materials for continued health and regular flowering. After the
plants have become established in the fertile composted mixture,
a monthly feeding with a complete fertilizer mixed in water at
the rate of a tablespoonful to the gallon should suffice. The
plants must never wilt, so careful attention to the matter of
watering is essential.
When a potted gardenia is received at Easter or Mother's Day
it should be kept in a cool moist spot. The dry atmosphere in
the average home is unsuitable to its continued welfare. Bud
drop is the first response to an uncongenial environment. Several
times a day the foliage may be lightly moistened with the mist
from a hand atomizer. The applicator sold with window clean-
ing fluid is suitable. Ammonium sulphate applied in liquid form,
one ounce to two gallons every two weeks, is desirable.

Greenhouse Culture
Several commercial greenhouses in Florida are producing
gardenia flowers successfully. The production of greenhouse
gardenias might be worthy of expansion in northern Florida.
Own-root plants are set from 15 by 18 inches to 18 by 24 inches
in raised beds or cypress boxes of rich, acid composted soil that
contains at least 50 % peat by volume. To control nematodes
and soil-borne diseases the growing medium must be sterilized
after it is placed in the benches or boxes. There are a number
of methods used to introduce steam into gardenia benches, but
perhaps the Thomas method is easiest. Two lines of drain tiles
are laid on the soil and steam is introduced after the entire bench






Florida Agricultural Experiment Station


is covered with a tarpaulin or with sisal kraft. The soil tempera-
ture should be held at 180 to 200 F. for at least a half hour.
Small quantities of soil can be sterilized by heating to 160 F.
for three or four hours.
Modern soil fumigants may be used to free greenhouse soils
of nematodes and soil-borne fungi. These must be used exactly
according to the direction sheet which accompanies each package.
After the plants have been set, high humidity is maintained
by syringing frequently during bright sunny weather. Mulching
with peat, oak leaves or tobacco stems is necessary as an aid in
holding an even supply of soil moisture. Be careful, however,
not to over-water, as this may cause bud drop.
One pound of copperas (ferrous sulphate) on 100 square feet
of bench space should be distributed monthly in order to maintain
acidity and a constant supply of iron.
A balanced commercial fertilizer known to be acid in reaction
should be used every month during growing weather.
A wire stake is set by each plant and the branches are bound
in by cord, raffia or other binding.

Diseases
The most serious disease of gardenias is stem canker
(Phomopsis gardeniae). Early symptoms are slightly sunken
discolored areas on the stems near the soil level. The infected
tissues become enlarged to form rough cankers. Here, the spores
of the fungus are produced to be distributed by splashing water,
cultivation and handling. In Florida's warm, humid summer-
time the disease may spread rapidly. Infection occurs through
wounds, so every possible precaution must be observed to avoid
injuring the bark. Infected plants must be destroyed. Bordeaux
mixture, copper-lime dust, a spray of fermate or zerlate used
around the plants, are suggested preventive. No cure is known.
When cuttings are taken for propagation they must be selected
from high up in the plant and immediately dipped in a fermate
bath (1 tablespoonful per gallon). Sterilized soil for potting is
recommended, as noted previously.
Leaf spotting diseases, sometimes quite prevalent, may be
checked by spraying with bordeaux mixture or fermate. This
should not be confused with tip burn, which may be caused by
fluctuating moisture and by a lack of usable iron.

Fig. 3.-The variegated-leaf gardenia appeals to some fanciers.






VOW,--










4 W
Se.






Florida Agricultural Experiment Station


Sooty mold, well known to everyone who grows gardenias, is a
fungus disease that injures by withholding light and preventing
gaseous exchange. The leaves become covered by a crusty black
film which is most unpleasant. This fungus lives on honeydew
from whiteflies and aphids. A 1 percent white summer oil will
cause the sooty film to roll off within hours after application.
Chlorosis, while not a parasitic disease, is a manifestation of
an abnormal condition and therefore may be considered a disease.
The loss of normal green color so that the veins appear bright
green on a yellow field may be due to several causes. In Florida
the most outstanding cause of chlorosis is lack of iron. A foliar
spray of copperas (ferrous sulphate) at the rate of a teaspoonful
to a gallon of rain water, with a half teaspoonful of detergent as
a spreader, will usually work a quick cure. If the soil is not cor-
rected, however, the foliage will develop chlorosis soon again,
brown areas will develop, and the plant will be stunted and un-
productive. The only permanent corrective method is to trans-
plant the chlorotic gardenia to a new site that has been prepared
with a known acid mixture that contains all necessary mineral
elements. Never apply superphosphate, bone meal, lime or any
material that will make soil basic in reaction. Much municipal
water in Florida is very alkaline and this, alone, is sufficient to
induce chlorosis in potted gardenias. Compost is lowered one
point by 3 pounds of aluminum sulphate in 50 cubic feet.
Chlorosis of the same pattern may be caused by overwatering,
low soil temperatures in wintertime or root-knot nematodes.
Bud drop is not a pathogenic disease, but as it reflects dis-
balance it can be classed as a disease. Despite much research
by able investigators, little is known about the cause of this
troublesome condition. Environmental factors which cause
flower buds to shed are excessively dry soil, excessively wet soil,
excessively low humidity, excessively cold soil or excessively
warm soil. Good light conditions, a constant optimum tempera-
ture of both air and soil, a medium-moist soil and a thick organic
mulch are helpful in preventing bud drop.
In Florida it is customary for speciality nurserymen to sell
budded field-grown balled and burlapped gardenias through
chain stores in April. These are excellent plants, well grown,
clean, free of root-knot and invariably well furnished with large
flower buds. The lifting, transporting, displaying, with attendent
sacrifice of optimum environmental conditions, usually results in
marked bud drop. Though consumers are justified in their com-






Gardenias in Florida


plaints, nothing can be done, under this system of merchandising,
to assure the holding and opening of flower buds. Gardenias,
carefully transplanted by the balled and burlapped method early
in the winter, should reestablish themselves well in advance of
flowering time.
Pests
Nematodes are the most serious pests of gardenias in Florida.
These minute worms feed upon the roots and cause galls to form.
Stunted, unthrifty growth, the decline of the plant and sub-
sequent death may follow. In southern Florida, nematode-re-
sisting Gardenia thunbergia used as a rootstock eliminates this
hazard. In northern Florida the planting site may be treated
with a soil fumigant before planting and then a mulch of leaves
four to six inches deep is kept over the root area at all times. If
it is planned to grow gardenias in containers the compost should
be sterilized (1600 F. for three or four hours).
Whiteflies are prevalent in Florida, where they are major pests
in the citrus industry. The eggs are laid on the under sides of
gardenia leaves. Here the young hatch and cause stunting as
they feed upon the cell sap. In addition, they secrete a liquid
upon which the sooty mold fungus grows. Parathion, 15%
wettable powder when used at 1 tablespoon per gallon of water,
will control whiteflies and eliminate sooty mold if used in May,
after the flowers are cut, and again in September when growth
has hardened. Caution: This is a very poisonous chemical and
persons have died from handling it carelessly. Wear a gas mask
and rubber gloves when mixing or applying parathion.
White summer oils, used at 1 to 2 % strength, have given good
control of whiteflies and sooty mold for many, many years.
Apply exactly as directed and do not use in very hot weather or
just prior to low temperatures.
Mealybugs are large scale insects that cover themselves with
white, cottony wax. As they multiply rapidly to form large
colonies and are voracious feeders, they have a depressing effect
upon the host plant. Parathion, 15 % wettable powder used at
the strength of a level tablespoon to a gallon of water, will kill
these harmful insects. A repeat spraying after 15 days will
clean up young mealybugs that have hatched in the interim.
Cottony cushion, soft brown, green shield and other tropical
scales are likely to attack gardenias. These will be controlled if
parathion is applied several times each year.
Leaf-rollers are small green caterpillars (moth larvae) that







Florida Agricultural Experiment Station


tie two terminal leaves together and then feed upon the tissues
of these leaves and the bud between them. When parathion or
DDT is used regularly these insects will not appear.
Red spider mites are eight-legged pests that dwell under pro-
tective webs and multiply very rapidly during warm, dry
weather. Parathion 15 % wettable powder 2 tablespoons in a
gallon of water will kill mites. Repeat in 15 days to destroy
young that have hatched in the interim. If it is not feasible to
use parathion, 300-mesh sulphur dust will effectively control
mites. An efficient, crank-type duster is needed so that the
sulphur will rise like smoke to cover all surfaces of leaves and
stems. Dusting sulphur should be applied on bright hot days so
that the element will volatalize and kill by suffocation.
All sprays must be applied at a considerable pressure so that
they are broken into a very fine mist and completely cover all
insects and parts of the plants. A knapsack or wheelbarrow
sprayer will be needed, as the little applicators that are sold
with household insecticides are completely ineffectual.


Diagnosing Gardenia Ills


SYMPTOM
Leaves turn yel-
low




Leaves are coat-
ed with black
film

Stems rough and
cracked near
ground
Leaves display
round spots that
turn brown
Bud drop


Leaves develop
a grayish, rusty
appearance

White, brown or
greenish blobs
below leaves on
terminal twigs


POSSIBLE
CAUSE
1. Iron chlorosis

2. Root-knot
nematodes
3. Cold soil
Sooty mold
fungus

Stem canker
fungus

Leaf spotting
fungi

Causes unknown


Red spider mites


Tropical scales'


RECOMMENDED
TREATMENT
Spray with copperas (ferrous sul-
phate) solution. Move plants to
acid composted soil.
Destroy infested plants.

Use bottom heat if possible.
Control whiteflies and other in-
sects with parathion 15% wet-
table powder, 1 tablespoon in a
gallon of water.
Destroy infected plants. Take cut-
tings from highest branches of
healthy plants. Use sterilized soil.
Spray with bordeaux mixture or
fermate regularly.

Keep soil uniformly moist, mulch
with 4-6 inches of leaves, try to
maintain reasonably high humid-
ity.
Spray with parathion 15% wet-
table powder, 2 tablespoons to a
gallon of water, or dust with 300-
mesh sulphur.
Spray with 15% wettable para-
thion mixed at the rate of a table-
spoon to a gallon of water.




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