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Institute of Food and Agricultural Sciences
University of Florida, Gainesville
tural Research Center
The Agricultural Research Center at Apopka was established primarily
through the efforts of local nurserymen and agricultural leaders who recog-
nized the need for research on problems associated with commercial foliage
Orange County purchased 18 acres of land and donated it to the Univer-
sity of Florida for the site. Building funds for the office building,
greenhouse, and storage building were .appropriated by the 1965 State Legis-
lature. Operating funds were appropriated by a special session of the
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 designed to closely
duplicate grower conditions with plants grown under shade cloth, fiberglass
and glass. The center also has over 2000 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.
Six 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 Asst. Entomologist Insect and Nematode
Pests of Ornamentals.
3. Dr. Richard W. Henley Assoc. Ornamentals Extension Specialist,
Ornamental Horticulture Extension Foliage.
4. Dr. Richard J. Henny Asst. Plant Geneticist Foliage Plant
5. Dr. James F. Knauss Assoc. Plant Pathologist Ornamental
6. Dr. Richard T. Poole Professor, Plant Physiologist Horticul-
ture and Physiology of Ornamentals.
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-76-7, 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.
Research Project RH-01069
Title: Effects of Photoperiod and Temperature on Growth and Flowering of
Certain Florists Crops.
Determination of optimum light and temperature for maximum growth of
high quality plants.
Regulation of light intensity during production of potted foliage is
important in acclimatization. Research has shown that light acclimatized
plants perform better under indoor conditions and provide higher consumer
satisfaction. Specific light intensities for various foliage plants are
provided in the September, 1975 Florida Foliage Grower. These intensities
are below levels previously suggested, but do not result in reduced product-
ion of foliage plants. Plants grown under low light intensities have a
smaller root system, but higher chlorophyll content.
Dieffenbachia exotica, Aphelandra squarrosa and Philodendron oxycardium
were placed in the dark for 3, 6 and 9 days at approximately 75F. Plants
removed had the same chlorophyll content as plants maintained under normal
light regimes. After one month there was no difference in quality of plants.
Philodendron oxycardium, Scindapsus aureus and Coffea arabica were
grown under various temperature schedules beginning January 17, 1975.
Night Temperature Day Temperature
March 25, plants were measured and no growth differences were noted.
Leatherleaf Fern averaged 2.1 fronds/sq. ft./mo during the months May,
June, July; 1.9 during August, September, October; 1.4 for November,
SDecember and January and 2.2 fronds for February, March and April.
Research Project RH-01555
Title: Weed Control for Ornamental Plants.
Evaluation of weed control techniques for reduction or elimination of
weed populations in commercial production of ornamental plants and deter-
miniation of the effect of these weed control techniques on yield of orn-
Herbicides were applied twice, initially and 6 months later, in a
one year period and Leatherleaf fern harvested 4 times during the year,
3 months after first herbicide application and every 3 months thereafter.
Yield data indicate Eptam, 5 pounds per acre per application, reduced
yield 2% when compared to hand weeded control, Granusil-X, 1 ppa, 5%,
Lorox, 1 ppa, 7%, Probe, 2 ppa, 8%, Princep, 2 ppa, 10%, Treflan, 2 ppa,
12% and Casoron, 2 ppa, 28%. All materials gave satisfactory weed control.
Research Project RH-01683
STitle: Effect of Growth Regulators on Ornamental Plants
Determination of the action of various growth regulators on ornamental
plants for control of growth and development for production of high quality
Gibberellic acid (GA) 200 and 400 ppm, Cytex, a kinetin, 2 and 4 ppm,
and Arest, 20 and 40 ppm, a growth retardant were sprayed on Philodendron
oxycardium and Neanthe bella palm. Growth regulators did not affect growth
increment, but GA did cause abnormal growth of Philodendron.
Schefflera were sprayed with 25, 50 and 75 ppm Arest. Three months
later water was withheld. The growth retardant had no influence on days
Research Project RH-01615
Title: Properties of Natural and Synthetic Media and Resulting Effects on
Production of Ornamental Plants.
Research on potting media has as major objectives the development of
low cost potting mixtures with physical and chemical properties conducive
to production of high quality plants, as well as desirable properties for
continued growth in the home. This research has as a basic commitment
identification of physical and chemical properties of good soil media.
Research is being conducted on twelve different peat sources, to
determine the differences in physical and chemical characteristics that
influence plant quality. Peat sources under study include native sources
as well as Canadian and European peats. Lack of adequate aeration (pore
space) has been identified as the major problem of several peats.
Several potting media used in production of potted foliage have been
tested on capillary watering mats. Best growth on constantly wet mats
was obtained from mixtures with excellent aeration characteristics such
as 2-1-1 Peat-Pine Bark-Shavings, while pure peat was not satisfactory.
On mats irrigated intermittently, where the capillarity was allowed to
break between waterings, pure peat was satisfactory, as was the 2-1-1 ratio
of Peat-Pine Bark-Shavings. Leaching or heavy application of water at the
surface of the medium at least once a month is necessary to control soluble
Influence of pot size on aeration of various potting mixtures has pro-
vided information that is of value in determining those media best adapted
to use in small, medium or large pots. In small pots, less than 4 inch,
mixtures high in peat must have at least 20% perlite or 15% sand to provide
proper drainage and aeration, and care must be taken to prevent packing when
Research Project RH-01107
Title: Macro-Element Nutrition of Certain Floricultural Crops.
Research under this project has as its aim, development of nutritional
programs that will maximize production efficiency and produce plants with
desired properties for continued growth under interior conditions. Research
in this area includes experiments on fertilizer sources, ratios and levels.
Data from many experiments has provided the published recommendations
now available on light and fertilizer requirements of foliage stock plants
and acclimatized potted plants. Fertilizer levels can be provided from
liquid, slow release or combined programs.
Research has shown that nutritional level of the soil at time of
transfer of a plant from the production area to utilization area can
strongly influence keeping quality. Therefore, acclimatization (condition-
ing) recommendations are very important.
Research has shown that tip burning of many foliage plants is due to
fluorine toxicity. Plant genera most severely injured include Chamaedorea,
Chlorophytum, Cordyline, Calathea, Dracaena, Maranta, Pleomele and
Spathiphyllum. Methods of reducing injury include elimination of super-
phosphate from the growing medium, raising medium pH to 6.0 to 6.5, using
irrigation water without fluoride where possible, and reduction of trans-
PLANT PATHOLOGY RESEARCH PROGRAMS
J. F. Knauss
Research Project RH-01021
Title: Nature, Cause and Control of Diseases of Tropical Foliage Plants.
Identification of major plant pathogens attacking tropical foliage
plants, cut fern and foliage and caladiums is a major objective. Often
the pathogen has been reported previously but is new to the host plant
being grown. In some cases, however, the pathogen was found to be
completely new to the U.S.A. Obtaining effective controls for plant
pathogens remain an important phase of this research project. Control
is achieved by both cultural improvements, development of known pathogen
free stock plants through tissue culture and information achieved in the
determination of non-phytotoxic and effective fungicides and bactericides.
Information on many new and/or previously undescribed diseases has
resulted from this work. Suggested cultural changes and knowledge
resulting from fungicide and bactericide testing (See: Florida Foliage
Grower, Vol. 10(9), Vol. 12(10), and Vol. 12(11); Florists' Review, May
17, 1973 and October 11, 1973) have enabled growers to effectively control
most major and minor disease problems. Indexed stock production via
tissue culture at ARC-A and in cooperation with Dept. Plant Pathology,
Gainesville, has produced indexed stocks of caladium, nephthytis, and
dieffenbachia. These stocks are presently under test for suitability to
Research Project RH-01518
Title: Diseases of Ornamental Plants Caused by Soil-Borne Pathogens.
Soil-borne plant pathogens are the most important and destructive
patheoen group attacking tropical foliage plants. Understanding the dis-
eases they cause, how they arise and determination of effective methods for
their control is the objective of this research project. Continued eval-
uation of soil fungicides has been and will continue to be an important
portion of research carried on under this project. Current emphasis is
being placed on evaluation of granular formulations for preplant incorpora-
tion in soil mixes. Combination drenches and rate (volume) of application
are also under investigation. Evaluation of soil fungicide for the control
of pythiaceous fungi will be a major part of this project. Current emphasis
is on experimental soil fungicides in granular forms for pre-plant soil
incorporation. Rates (volume) and concentration of drench applications are
also under investigation.
The major soil-borne plant pathogens have been identified as Pythium
spp., Phytophthora spp., Rhizoctonia solani and Sclerotium rolfsii. Infor-
mation on cultural and chemical methods for control have been published
(See: Florida Foliage Grower, Vol. 10(9), Vol. 13(3) and Florists' Review,
May 2, 1974). Results of soil fungicide testing at ARC-A, have assisted
in the clearance for use in the foliage industry of several soil fungici-
des in common use in the industry today. A new experimental compound
CGA-182 has proved to be particularly effective for Phytophthora parasitica
and Pythium splendens and Pythium aphanidermatum at concentrations of
active ingredient between 10-25 ppm for drench applications and at 5-25
oz/cu yd of a 1% granular soil incorporated.
Research Project RH-01657
Title: Non-Chemical Control of Soil-Borne Fungal Pathoqens of Container-
Grown Ornamental Plants.
Microorganisms which inhabit soils or media employed for growing foliage
plants may possess the ability to be antagonistic to soil-borne plant
pathogens. The objective of this project is the isolation of soil
antagonists and their subsequent manipulation in growing media to produce
effective control of pythiaceous fungi through antagonism and with
minimum employment of soil fungicides.
Several isolates of actinomycetes have been found to exhibit a high
degree of antagonism in petri plate culture to foliage plant pathogens
belonging to the genera Pythium and Phytophthora. An experimental system
for low temperature pasteurization (aerated steam sterilization) has been
constructed and is in use to help select out high temperature tolerant
antagonistic microorganisms. In addition to Florida isolates actinomycetes
have been obtained from commercially-available composted bark potting
mixes reputed to non-conducive to the growth of Phytophthora spp. In Vivo
tests for antagonist activity are planned for 1977.
ENTOMOLOGY AND NEMATOLOGY RESEARCH PROGRAMS
R. A. Hamlen
Research Project RH-01668
Title: Biology and Control of Insects and Related Pests on Ornamental
The objectives of this program are to identify, describe and solve the
insect, mite and related pest problems encountered by the Florida commer-
cial foliage, fern and caladium growers. Presently major emphasis is being
placed on the evaluation and selection of effective means of chemical con-
trol that are safe both to the plant and the environment. Techniques also
are under evaluation for the control of pests under interior environments.
Present and future plans involved additional chemical testing for pest con-
trol along with development of new programs to evaluate non-pesticide means
of pest control.
The major insect and mite pests have been identified as the broad mite,
Polyphagotarsonemus latus; several foliar inhabiting mealybugs, Pseudococcus
longispinus, Phenacoccus solani, Ferrisia virgata, Planococcus citri; root-
feeding mealybugs, Rhizoecus spp.; the green peach aphid, Myzus persicae;
numerous soft-scales, Coccus spp., Saissetia spp.; armored scales; thrips;
and most importantly, the two-spotted spider mite, Tetranychus urticae.
However, due to the enormous number of the plant species produced, new
pests are constantly being observed. Results of insecticide and miticide
evaluations for effectiveness and potential phytotoxicity at ARC-A have
assisted in the development of programs for control of these pests and in
the registration of pesticides for use by the ornamental foliage industry.
Various insect growth regulator (IGR) chemicals, i.e., insect controlling
chemicals that do not poison the insect as do conventional types, but rather
are toxic to the pest by inhibiting normal development; have proven highly
effective and appear as alternatives to the use of hazardous pesticides.
IGR development will continue to be an important part of this project.
Evaluations of aerosol formulations for use indoors has made available to
plant retailer and consumer needed information for selection of effective
and safe chemicals for control of pests on indoor foliage plants.
Research Project RH-01662
Title: Biology and Control of Nematodes Affecting Ornamental Crops.
Research is being directed toward the identification and solution of
nematode problems faced by the Florida foliage, fern and caladium growers.
Currently, major activity concerns the evaluation of registered and experi-
mental nematicides for effectiveness and safety. Future objectives call
for further chemical evaluations as well as the establishment of new re-
search areas for the integration of chemical and non-chemical means of
Major soil nematodes appear to be root-knot, Meloidoqyne spp.;
Pratylenchus spp.; the burrowing nematode, Radopholus similis; the
cactus cyst species, Heterodera cacti; while foliage inhabiting types
are Aphelanchoides spp. Based on effectiveness and phytotoxicity
testing of various nematicide formulations, controls are now available
for these pests under ground bed and container production.
GENETIC RESEARCH PROGRAMS
R. J. Henny
Research Project RH-01553
Title: Genetic Improvement of Ornamental Plants.
The development of new or improved cultivars of ornamental foliage
plants acceptable to both the producer and consumer is a major objective
of this program. A number of species within selected genera will be
gathered to serve as the genetic base for future breeding work. Intra-
specific and interspecific crosses within genera will be the main method
of transferring genetic variability to subsequent progenies. Another
important objective is the collection of any information relevant to a
foliage breeding program. Factors such as floral morphology, pollen
structure, chromosome numbers, pollination methods and the presence of
genetic sterilities or incompatibilities will be studied. This infor-
mation is lacking for almost all foliage plants at this time. Tissue
culture is being studied as a tool for rapid propagation of future
selected seedling lines. Other plans include irradiation and/or
colchicine treatment of established cultivars as a means to generate
new types or variants of plants while avoiding the lengthy periods of
time often linked with sexual regeneration.
Four genera of foliage plants (Aglaonema, Calathea, Dieffenbachia and
Maranta) have been selected for the major breeding effort in this program.
A less concentrated study will be made with Aphelandra, Dracaena,
Peperomia and Spathiphyllum species. A collection of species from each
genera is now under way. Fruit set has been induced following artificial