The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
/e -7 e- 7
4 Jiz'Slh.:. Li _RY-lo
The Agricui trial es arch C nter at Apopka was established primarily
through he efforts' of local nur erymen and agricultural leaders who recog-
nized th need for research onp oblems associated with commercial foliage
plant pr d~cfbin: Univ. of riodr
Orange County purchased 18 acres of land and donated it to the Univer-
sity of Florida for the site. Building funds for an office building, green-
house, and storage building were appropriated by the 1965 S ate Legislature.
Operating funds were appropriated by a special session of tIe Legislature
in 1968 as part of the special appropriation for the Institute of Food and
Agricultural Sciences. The center officially opened September 1, 1968 with
only the office building completed.
Research facilities at this center have been vastly expanded since 1968
and have been designed to closely duplicate grower conditions with plants
grown under shade cloth, fiberglass and glass. Presently there are over
40,000 sq ft of research area for plant production. The center also has over
2,000 sq ft of controlled environment rooms to test indoor growth of foliage
plants under consumer conditions.
The primary objective of this research center is to conduct research
and assist in State Extension activities on commercial ornamental horti-
cultural crops of Florida. The major industries involved are foliage plants,
cut ferns and woody plants used for cut foliage.
Seven faculty positions presently located at the Agricultural Research
Center Apopka and their area of specialization are:
1. Dr. Charles A. Conover Professor, Ornamental Horticulturist and
Center Director Administration, Soils and Nutrition.
2. Dr. Ronald A. Hamlen Assoc. Professor, Entomologist Insect and
Nematode Pests of Ornamentals.
3. Dr. Richard W. Henley Assoc. Professor, Ornamentals Extension
Specialist, Ornamental Horticulture Extension Foliage.
4. Dr. Richard J. Henny Asst. Professor, Plant Geneticist Foliage
5. Dr. James F. Knauss Assoc. Professor, Plant Pathologist Orna-
mental Plant Diseases.
6. Dr. Richard T. Poole Professor, Plant Physiologist Horticulture
and Physiology of Ornamentals.
7. Open Asst. Professor Cut Foliage, Research and Extension.
This report summarizes active research projects. Correspondence with
research or extension faculty regarding completed projects or extension
publications should be addressed to: Agricultural Research Center Apopka,
Rt. 3 Box 580, Apopka, FL 32703.
Telephone Number: (305)-889-4161.
ARC-Apopka Research Report RH-78-7. C. A. Conover, R. A. Hamlen, R. W. Henley,
R. J. Henny, J. F. Knauss and R. T. Poole.
HORTICULTURAL RESEARCH PROGRAMS
C. A. Conover and R. T. Poole
Research in this area has as its objective the development of new or
improved methods of increasing yield and quality of foliage, fern and cut
woody foliage. Major research areas include nutrition, media, photoperiod,
light intensity, temperature, growth regulators, herbicides and certain
cultural changes such as irrigation methods and frequency.
Immediate plans are to develop optimum cultural recommendations for
the major foliage crops, fern and cut woody foliage. Future plans will
include development of new crops and methods of changing the appearance
of crops presently grown.
Purpose: Although most foliage plants are easily propagated, the proper
selection of soil medium, soil and air temperature, light intensity,
irrigation method, type and condition of cutting, growth regulators
and maintenance of pest free materials is important and necessary in
order to produce a quality plant economically.
Approach: Stock plants are being grown under varying light intensities
where they receive different quantities of fertilizer. This is a con-
tinuation of several preliminary experiments that showed % rooting was
strongly affected by light and fertilizer levels received by the stock
plants. Growth regulators are also being applied to determine their
influence on rooting and subsequent growth of cuttings from stock plants
grown under different conditions. Crotons are the main crop being tested
at the present time.
Proram Achievements: Improvement in percentage of plants which root and
reduction in time required for development of roots has been shown to
be influenced and greatly improved by many factors. The importance of
vigorous, healthy stock plants has been demonstrated. Cuttings from
stock grown in low light and supplied with inadequate nutrition produce
small cuttings which require longer periods to root. Growth regulators
have been shown to be beneficial for a few cuttings such as Aphelandra,
Ficus and Polyscias. Additions of small amounts of fertilizer and
dolomite have been shown to be very beneficial when incorporated into
the propagation medium. Age is particularly important when germinating
tropical foliage seeds. Seeds should be obtained fresh and planted as
soon as possible. Propagation time of tropical plants can be reduced
greatly when medium temperatures are maintained between 75-80F.
Purpose: Need for information on fertilizer sources, levels, ratios and
frequency of application for the hundreds of foliage cultivars grown
commercially has created a need for fertilization research to maximize
production of quality plants.
Approach: Experiments being conducted in this area include effect of nitrogen
source on foliage plant growth and acclimatization, influence of several
new slow release fertilizer sources in comparison with liquid fertilizer
and Osmocote and continuation of fertilizer level testing on cultivars
not previously listed in published articles. Effect of macro and micro
nutrients on bent tip of Aglaonema is also being examined.
Program Achievements: Utilization of research results by growers from many
experiments conducted over the last seven years has allowed production
of higher quality crops. At present, suggested fertilizer levels for over
thirty species are listed in a research report and suggested tissue levels
for these plants have also been published. A major effect of fertilization
research has been a reduction in amount of fertilizer used, and therefore,
a better quality product being sold to consumers. The reason this has
occurred is that reductions in soluble salts present in potting media at
time of sale for placement indoors results in increased longevity.
Purpose: Extensive research has been conducted over the past 7 years on
acclimatization to aid in maintaining plant quality when plants are
moved from a production environment to an interior environment.
Approach: Experiments have been conducted on controllable environmental
factors during production that may influence conversion to an interior
environment.. These have included light, fertilization, growing medi'im
and watering. Since programs have been developed for most of the
major foliage plant genera being grown, emphasis has now been placed
on shipping and storage problems associated with plant decline. Several
experiments with Ficus benjamin have shown that up to 10 days dark stor-
age is not injurious to acclimatized plants, but is not acceptable for
those not properly acclimatized.
Program Achievements: Results of many experiments have indicated that ac-
climatization may be accomplished by growing plants under high light
and nutrition, and then holding them under reduced light and nutritional
levels for 3 to 9 months prior to interior use, or growing them under re-
duced light on lower fertilizer regimes. The best system is to grow the
plants under proper light and nutritional levels for acclimatization, as
a higher quality product is produced in less total time, and such plants
are also easier to ship and store for short periods.
Purpose: Industry requests for information on growth and maintenance of foliage
plants indoors continues to increase. For this reason, the level of re-
search effort has been increased in an attempt to solve some of the most
pressing problems facing the interior plant industry.
Approach: Experiments previously conducted in this area have examined the
influence of light intensity on interior plant quality and the influence
of varying fertilizer programs. More recently, the influence of light
duration and intensity have been examined, and at present, the effect
of light duration, intensity and fertilizer levels on plant growth are
being examined simultaneously. These experiments are all aimed at helping
people growing plants indoors maintain quality for longer periods.
Program Achievements: Influence of light intensity research has shown that
most plants need a minimum of 75 to 100 foot-candles of light for 12
hours a day to maintain quality. Under such conditions, very little
fertilizer is required, but if light levels are increased to 150 foot-
candles or more, considerable plant growth will occur and higher ferti-
lizer levels will be required. Recent research on light durations have
shown that several foliage plants maintain higher quality indoors when
they do not receive more than 12 to 18 hours of light a day. When con-
tinuous lighting was provided, quality of Brassaia, Chamaedorea and
Dieffenbachia declined tremendously.
Purpose: Relate soluble salts data to fertilizer recommendations for foliage
crops which vary from a low of 600 to a high of 2400 pounds of nitrogen
per acre per year and to reduce amount of total water and fertilizer
applied to plants.
Approach: Plants are watered constantly with varying rates of fertilizer,
750 ppm nitrogen is the maximum rate applied. Known quantities of water
are applied so that the exact amount of fertilizer applied can be cal-
culated. Some plants are given restriction volumes of water so that no
leaching occurs. Bi-weekly collection of the leachate are analyzed for
soluble salts and pH. The volume of leachate is determined.
Program Achievements: Experiments have been conducted which show that most
foliage plants will grow satisfactorily even though fertilizer quantity
varies greatly. Experiments have also shown that excess fertilizer re-
duces growth of plants even though visible symptoms generally associated
with excess soluble salts, such as necrotic edqes, are lacking and good
quality foliage plants can be grown with much less water and fertilizer
usually applied. Research results have also shown that heavily fertilized
plants are much more susceptible to mite injury.
Purpose: Many tropical indoor plants, besides having attractive foliage, pro-
duce showy flowers which enhance salability of the plants. There is a
need to determine methods of manipulating the environment so that these
plants can be forced into bloom throughout the year. The capability of
forcing plants into bloom whenever desired is helpful in a p]ant breeding
program to enable fertilization of plants by other plants that bloom at
different seasons of the year and also to reduce time between different
generations of plants.
Approach: Plants are grown under various combinations of light conditions,
of intensity and duration. While subjected to these varying light con-
ditions, plants are maintained with proper nutrition, irrigation and
Program Achievements: Aphelandra have been shown to be responsive to light
intensity, not photoperiod. Five hundred foot-candles and below will
maintain Aphelandra in a vegetative state. Aphelandra grown in an
environment of one thousand foot-candles or above will produce flowers.
Christmas cactus will bloom anytime of year if given the proper photo-
period. The plants do not need to be subjected to drought, low
temperatures or inadequate fertilization to produce a plant with many
blooms. Three weeks of short days, light from 8 a.m. to 5 p.m. will
produce some flowers, five weeks of short days will produce a Christmas
cactus with many blooms anytime of the year.
Purpose: The selection of the proper light level for foliage plant production
is very important, since it controls appearance, growth rate and longevity
indoors. Light levels supplied plants indoors are extremely important and
low light levels are one of the most frequent causes of unsightly plants.
Level of light influences the amount of fertilizer required to produce
good quality plants.
Approach: Several experiments on light (shade levels) are being conducted to
determine those levels that provide best appearance, growth and acclima-
tized plants. Shade variables range between 30, 47, 63 and 80 percent
shade and most are also combined with different fertilization levels.
The effect of duration of light, constant vs. 12 and 18 hours, is being
studied in combination with light levels and fertilizer levels.
Program Achievements: Publication of light intensity research has resulted in
adoption of recommended light intensities by a majority of the foliage
industry. Foliage plants produced under reduced light have larger leaves,
with increased chlorophyll levels, more open plant appearance, longer
internodes and reduced stem caliper. Such plants are better'adapted to
utilization indoors and sell more readily. Constant light of sufficient
intensity, such as sometimes found in malls can reduce the quality of
foliage plants. Light levels influence the degree of severity of damage
when plants are subjected to constant light.
Purpose: To determine satisfactory ingredients for the foliage potting medium
and the best proper maintenance of the medium to produce quality foliage,
also, determine the physical and chemical properties and their relation-
ship to quality foliage plant growth.
Approach: Since soil medium or substrate can greatly influence growth and
quality of foliage plants, and the combinations of medium ingredients
that will produce satisfactory foliage plants are numerous, medium studies
in combination with watering and fertilizing practices are being con-
ducted to determine if a specific medium can produce good plants under
one or several watering and fertilizing schedules. Cation exchange cap-
acity, water holding capacity, porosity, specific gravity and pH of
various mixes and ingredients are determined and correlated with growth
Program Achievements: Previous research at this Center has shown that many
combinations of ingredients will produce good quality plants in a rel-
atively short time and that the well aerated mixes frequently require
more frequent irrigation than a less porous mix. However, a tight mix,
one with low pore space, produces poorest growth of foliage plants unless
extreme care is taken not to over-water. Cation exchange capacity and
water holding capacity are not frequently limiting physical character-
istics of soil for plant growth. Plants also tolerate a wide range of pH
and soluble salts.
PLANT PATHOLOGY RESEARCH PROGRAMS
J. F. Knauss
FOLIAGE PLANT INDEXING TISSUE CULTURE PROGRAM
Purpose: Develop and evaluate known pathogen-free stocks of selected foliage
plants for eventual release to the'foliage plant industry. Develop in-
formation to provide a better understanding of the reasons behind contam-
ination in plant tissue.cultures. Develop more effective methods for the
handling of tissue cultures after planting out in soil media.
Approach: Plantlet lines are developed through tissue culture and indexed
for known plant pathogens employing appropriate pathological methods.
Once a plant line has been thoroughly indexed, multiplication studies
are initiated to develop methods of increase and subsequent handling of
the tissue cultures.
Studies to determine the nature and epidemology of tissue culture
contaminants ,have been initiated. The effects of the environment on
explant sources and of antibiotics are underway.
Program Achievements: Many of the commercially-produced Dieffenbachia types
have been indexed for all known Dieffenbachia pathogens and are being
maintained in tissue culture for horticultural evaluations to determine
acceptability for introduction into the industry. Several lines of D.
maculata 'Perfection' have been selected for final evaluations with
release tentatively scheduled in early 1980. Other plant types presently
in the indexing program are species of Aglaonema, Dracaena and Philodendron.
Initial studies have indicated antibiotics may have only limited
application in commercial plant tissue cultures. Post treatment of explant
sources to dry, cool environments for at least several weeks will aid in
obtaining contaminant free explants. Bacterial contaminants can exist
within plant tissue cultures and not exhibit growth in the medium until
later division expose the contaminant to the medium surface..
FOLIAGE PLANT DISEASE IDENTIFICATION AND CONTROL
Purpose: Identify important pathogens of foliage plants and develop effective
and safe methods for their control.
Approach: Studies are continuing to determine the identity of pathogens
affecting foliage plants in production. Isolation into pure culture
and the later reinoculation into healthy plants are steps used to
determine pathogenicity. Undescribed diseases are numerous because of
the many plants grown, the abundance of pathogens, and the very favorable
environment for disease development. Wherever possible cultural methods
for control are investigated. Chemical control compounds, where needed,
Program Achievements: The list of new or previously undescribed diseases in-
creases each year. Specific information on these diseases may be found
in recent publications printed in the following journals and newsletters:
Foliage Digest, Florida Foliage Grower, Plant Disease Reporter, Phyto-
pathology, and the Proceedings of the Florida State Horticultural Society.
A comprehensive treatment of foliage plant diseases and their control may
be found in Vol. 12 (10), Vol. 12 (11), and Vol. 13 (3) of the Florida
DISEASE CONTROL CHEMICALS REGISTRATION AND RE-REGISTRATION
Purpose: To provide data necessary to'ensure the continued availability of
disease control compounds that are effective and non-phytotoxic in the
control of tropical foliage plant pathogens.
Approach: Tests on efficacy and potential phytotoxicity are conducted under
greenhouse conditions upon control compounds deemed critical to the Future
and success of the foliage plant industry. Particular attention is paid
to develop the needed data for re-registration and label expansion on
the critical compounds.
Program Achievements: During the past several years, numerous studies have
been conducted utilizing the following compounds: Banrot, Benlate, Cap-
tan, Daconil, Fermate, FORE, Kocide 101, Manzate 200, Streptomycin,
Truban WP, Truban EC, and Zineb. In addition, a promising new compound,
CGA 48988, specifically for control of pythiaceous fungi has been under
test for several years. These studies have produced data that have al-
lowed publication of specific concentrations and rates of application
for many of the compounds presently in use in the foliage plant industry.
ENTOMOLOGY AND NEMATOLOGY RESEARCH PROGRAMS
R. A. Hamlen
FOLIAGE PLANT PRODUCTION PESTS IDENTIFICATION AND CONTROL
Purpose: Identify insect, mite, nematode and other pests in foliage pro-
duction and develop effective and safe methods for their control.
Approach: Visual and microscopic observations are made of infested plant
material and that suspected to be infested to determine the identity
of pests. Pest problems are numerous in production due to the
number of foliage plant species grown, the intensive culture and the
favorable environment for rapid pest population development. Cultural
methods of control, whenever possible, are investigated. Chemical
controls including pesticides, microbial insecticides and insect growth
regulators are evaluated if necessary.
Program Achievements: The tropical foliage plant industry is a relatively
new area of ornamental horticulture and many previously undetected
pest problems have been identified including species of aphids (Myzus,
Aphis), mealybugs (Phenacoccus, Pseudococcus, Planococcus), scales and
thrips (Hercinothrips, Heliothrips), while lepidopterous larvae (Spodop-
tera) and whiteflies (Trialeurodes), are potentially serious pests.
Soil inhabiting pests include fungus gnats (Bradysia), root mealybugs
(Geococcus, Rhizoecus) and nematodes (Heterodera, Meloidogyne, Praty-
lenchus, Radopholus). Mites are the most destructive pests with the
tetranychid (spider mites), tarsonemid (broad and cyclamen) and tenui-
palpid (false spider) mites being the most important pests in foliage
production. Specific information on foliage pest identification and
control can be found in the Florida Cooperative Extension Service Bul-
letin 2-3M-78 and the Foliage Digest 1(1) and 1(5).
CONTROL OF FOLIAGE PESTS UNDER INTERIOR ENVIRONMENTS
Purpose: Identify important pests of indoor plants, evaluate and develop
effective and environmentally acceptable methods of control.
Approach: The increasing use of foliage plants indoors has increased demands
for better quality plants. Pests often gain entry to indoor plants by
escaping detection during production and by surviving the most rigorous
control programs. Standard and experimental insecticide, miticide and
insect growth regulator aerosol and fumigant formulations have been
evaluated for indoor use.
Program Achievements: Evaluations demonstrated effectiveness and safety to
specific foliage plant species. These tests have made available to plant
retailers and consumers needed information for selection of effective and
safe chemicals for control. Specific information can be found in Florists'
Review 159(4128) and the Journal of the American Society for Horticultural
NONCHEMICAL CONTROL OF MITES IN PRODUCTION AND INDOORS
Purpose: To develop acceptable alternatives to the total chemical approach
in spider mite control on tropical foliage plants.
Approach: Spider mites are a most serious pest of tropical foliage plants
and chemical controls are often inadequate, cause phytotoxidity and
when regularly used, result in resistant mite populations. The importance
of predaceous mites (phytoseiids) as biotic agents for control of spider
mites is recognized. The specific predaceous mite, Phytoseiulus macro-
pilis, is under evaluation to determine its usefulness.
Program Achievements: Evaluations indicate P. macropilis has the ability
to effectively control spider mites under greenhouse environments.
Additional research concerns the timing and number of predators for
release, integration with cultural and chemical methods as well as
usefulness under interior environments. Specific information is
available in the Proceedings of the Florida State Horticultural
Society Vol. 91.
INSECT, MITE, NEMATODE AND OTHER PEST CONTROL CHEMICALS REGISTRATION AND
Purpose: Provide effectiveness and plant safety data to ensure the contin-
ued availability of pest control chemicals for use in the foliage plant
Approach: Tests on effectiveness and potential phytotoxicity are carried out
under greenhouse and shade house conditions. New experimental compounds
that show potential usage are included whenever possible and emphasis is
being given to compounds of low mammalian toxicity. Presently, efforts
are to obtain data required for the re-registration and label expansion
of pesticides essential in production of quality foliage plants. Major
funding of this program is from IR-4 and USDA minor use registration
programs, chemical producers and the Florida tropical foliage industry.
Program Achievements: Specific concentrations, application times and tech-
niques have been developed for various compounds. Registrations include
diazinon and Vydat&t and chemical producers have petitioned for regis-
trations of other compounds for use on tropical foliage plants.
GENETIC RESEARCH PROGRAMS
R. J. Henny
DETERMINING BREEDING POTENTIAL OF SELECTED FOLIAGE PLANTS
Purpose: To develop new or improved cultivars of ornamental tropical foliage
plants acceptable to both producers and consumers.
Approach: Studies are conducted concerning the breeding potential of dif-
ferent genera of foliage plants. Information such as floral morphology,
pollination methods, pollen structure and storage, pollen tube growth
and the presence of genetic incompatibilities or sterilities is collected.
Intraspecific and interspecific crosses are used as the main means of com-
bining desirable traits. The inheritance of various traits is noted and
used as a guide in planning future crosses. Present and future plans in-
clude screening pathogen-free Dieffenbachia from the plant pathology pro-
gram as well as seedlings from the breeding studies.
Program Achievements: Several species of Dieffenbachia, Maranta, Aglaonema
and Aphelandra have been collected and are being grown. Seeds have been
obtained from self-pollination of several Maranta types and from
several Dieffenbachia crosses. Information concerning inheritance
of leaf and petiole variegation patterns in Dieffenbachia is being
developed. The ability to produce seeds from different interspecific
crosses of Dieffenbachia indicates the potential for future develop-
ment of new plant types. Embryo culture has been used successfully
to overcome germination problems with the Maranta seeds. Studies
with pollen have shown methods of storing Spathiphyllum and Vriesea
pollen safely up to 4-6 months.
HORTICULTURAL EXTENSION PROGRAMS
R. W. Henley
The State Extension Foliage Specialist was located at the Agricultural
Research Center Apopka due to the high concentration of commercial foliage
producers in Central Florida and the close proximity to University of Florida
faculty involved with'tropical foliage research.
EXTENSION FOLIAGE PROGRAM AREAS:
1. Edit Foliage Digest A monthly magazine for the foliage industry
published by the Foliage Education and Research Foundation, Inc.
2. Co-edit Foliage News A monthly newsletter for County Extension Aqents
3. Co-coordinatelthe National Tropical Foliage Short Course.
4: Coordinate regional short courses for foliage plant producers and
foliage plant retailers.
5. Help County Extension Horticulturists with aspects of their programs
pertaining to foliage production or utilization.
6. Assist tropical foliage plant growers with production problems.
7. Prepare visual aids on foliage plant production and utilization for
County Extension Agents and horticultural teachers.
8. Develop miscellaneous publications pertaining to both the commercial
foliage plant industry and amateur interests.