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C. A. Conover, L. S. Osborne and A. R E LIBRARY
University of Florida, IFAS
Agricultural Research and Education Centeri, o
AREC-A Foliage Plant Research Note R -1984"i 1600
I.F.A.S.- Univ. of Florida
The foliage industry in Florida began in 1914 w h to-E
(Nephrolepis exaltata 'Bostoniensis'), and it is fitting that Boston ferns
are still an important aspect of the foliage industry. No one can be sure
how many cultivars of Nephrolepis exaltata exist, because new forms are
being discovered all the time; however over 50 cultivars are listed in
Boston ferns grown in greatest numbers include Nephrolepis exaltata
'Bostoniensis', 'Bostoniensis Compacta', 'Florida Ruffle', 'Maasil' and
'Rooseveltii'. Some other cultivars of Nephrolepis exaltata sold in the
industry include Curly, Fluffy Duffy and Petticoat. Although there are
several other species of Nephrolepis, none have the popularity evidenced by
Nephrolepis exaltata. Historically, Boston ferns have been grown by off-
sets from runners, but in recent years tissue culture plants have become
common in the industry.
Boston Ferns have a wide tolerance to changing light levels, but grow
well when receiving 1500 to 3000 ft-c, with best quality usually produced
near 2000 ft-c. Suggested fertilizer level is 1500 Ib N/A/yr from a 3-1-2
ratio fertilizer source; liquid or slow-release (equivalent to 34.5 lb N,
11.5 Ib P205 and 23.0 lb K20/1000 ft /yr.
Potting media utilized for Boston fern should have high water holding
capacity, good aeration and not dry rapidly. Amendments should Pnclude a
low to moderate level of micronutrients such as 1 lb MicroMax/yd and
sufficient dolomite to adjust medium pH to 5.0 to 5.5. Higher pH levels
have been shown to slightly reduce growth rate. Suggested air temperature
for best growth is 650F minimum and 950F maximum; however, Boston ferns
will tolerate slightly lower and higher temperatures without great change
in growth habits.
iIn this article 'Boston Fern' is used collectively for cultivars of
2Professor, Ornamental Horticulture and Center Director; Assistant
Professor, Entomology; and Associate Professor, Plant Pathology,
respectively. Agricultural Research and Education Center, 2807 Binion
Road, Apopka, FL 32703.
Symptoms Fern has gray cast with reduced growth rate and few runners.
Control Boston fern will turn gray if it does not receive sufficient
water, and growth rate and runner production will be decreased if
potting medium is not moist all the time. Increase irrigation to
supply sufficient water.
2) Weak fronds
Symptoms Plants have a reduced number of fronds that are long, weak
and pendulous. Fronds are usually dark green in color and overall
plant quality is poor.
Control Increase light level to reduce frond length and increase
strength. Too much light will cause fronds to become light green in
3) Leaf Tip and Runner Burn
Symptoms Frond tips and leaflets and runner tips turn brown and die.
Control High soluble salts have been associated with tip burn and
leaching of media with good quality irrigation water will reduce
problem. In other cases tip burn has been associated with chemical
phytotoxicity frma sprays or poor quality irrigation water.
Nephrolepis exaltata cultivars are susceptible to few foliar and root
diseases. The most common and probably most important diseases are Rhizoc-
tonia aerial blight and Pythium root rot. Since both of these diseases are
soil-borne they can be controlled by either cultural (use of pathogen-free
potting media) or chemical means (fungicide drenches). Occasionally nema-
todes are also found on this crop.
1) Pythium root rot (Pythium spp.)
Symptoms Boston fern which are infected with Pythium spp. show a
variety of symptoms including stunting, wilting and graying or yellowing
of fronds. Examination of the roots shows a stunted, brown root system
with little vigor. The outer portion of the roots frequently falls away
from the inner core. Gray, water-soaked areas occur on portions of the
roots which are not completely rotted. Since ferns with root rot do not
always wilt, observation of a gray overcast to the foliage may signal
Control A pathogen-free potting medium is the first step to control of
pythium root rot and other root pathogens. Plants should be produced
fran pathogen-free stock and grown in new or sterilized pots on raised
benches. Chemical control of pythium root rot can be achieved with
ethazole (Truban 25 EC or 40.7 F are both labelled) as well as a
combination product of ethazole and thiophanate methyl (Banrot 40WP is
2) Rhizoctonia aerial blight (Rhizoctonia solani)
Symptoms Rhizoctonia aerial blight occurs primarily during the summer
months. Disease development can occur in less than a week, so plants
should be checked carefully and frequently. Brown irregularly shaped
lesions form anywhere in the foliage, but most commonly within the crown
of the plant which is often wet. Sometimes the first lesions form near
the top of plant confusing the source of the disease (the soil). The
lesions spread rapidly and cover the entire plant with the brown weblike
mycelium of the pathogen.
Control Cultural control of this disease is the same as that discussed
for pythium root rot. Since this pathogen inhabits the soil both the
roots and the foliage of the plants must be treated to provide optimal
disease control. A combination drench spray will best accomplish
this. Bencmyl (Benlate 50 WP is registered) provides good control of
rhizoctonia aerial blight. Chlorothalonil (Daconil 75 WP and 4.17 F) is
also very effective in controlling this disease although not registered
for this crop.
1) Lesion nematode (Pratylenchus spp.)
Symptoms Nematode infested plants appear similar to plants with fungal
root rot disease. Graying of foliage, a sign of water stress, is
Control Cultural control of lesion nematodes is the same as that
discussed for Pythium root rot. Chemicals which control nematodes
include aldicarb (Temik G) and oxamyl (Vydate L) which are both effec-
tive and registered for control of nematodes on fern.
PHYTOTOXICITY OF FUNGICIDES ON BOSTON FERN
Banrot 40WP Maneb compounds
Captan 50WP UNSAFE
Daconil 4.17 F and 75WP Agri-Strep
Truban 25 EC and 40.7 F Ornalin 50WP
Pesticides were tested at recommended rates and intervals.
MAJOR INSECT AND MITE PESTS
The major arthropod pests of Boston fern include caterpillars, mealy-
bugs, scales and thrips. Mealybug and scale infestations are typically the
result of bringing infested plant material into the greenhouse. Moths
(adult stage of caterpillars) and thrips have the ability to fly and thus
invade the greenhouse from weeds and other infested plants outside. In the
control section a few of the many registered and effective pesticides will
be listed. For a complete listing please consult the references at the end
of this report. Because of the numerous varieties grown in the greenhouse
a small group of plants should be tested for phytotoxicity prior to
treating the entire crop. The list given in this section should be used
only as a guide to the sensitivity of this plant to pesticides.
1) Caterpillars (worms)
Symptoms Infestations are easy to detect because worms, their excre-
ment and the damage they cause, are usually visible to the unaided eye.
Damage appears as holes in the center or along the edges of foliage.
Old damage can be distinguished from new by the calloused appearance of
the damaged areas (worms are usually gone by this time).
Control Lannate, Orthene, Dursban, Sevin, Dycarb, Mavrik, and Bacillus
thuringiensis are effective in the control of various worm species.
Symptoms Mealybugs appear as white cottony masses in frond axiles, on
the lower surfaces of fronds and on the roots. Honeydew and sooty mold
are often present, and infested plants become stunted and, with severe
infestations, they begin to die.
Control Systemic materials are preferred. Examples of chemicals which
have systemic activity are: Dimethoate, Disyston, Metasystox-R, Orthene,
and Vydate. Bendiocarb and Mavrik appear to be as effective as some of
the systemic materials. However, you should note that some of these
materials can damage fern. Control of root mealybugs is accomplished
with soil drenches with an insecticide. Diazinon and Vydate are the
only insecticides registered for this purpose but both can cause same
phytotoxicity. When pesticides are applied to the soil, care must be
taken to assure that the pots have good drainage and that no saucers are
attached or phytotoxicity may result.
Symptoms Infested plants become weakened or stunted and begin to die.
Scales can be found feeding on fronds and stems. Their shape, size, and
color are variable and many are hard to distinguish from the plant
material on which they are feeding.
Control See Mealybugs
Symptoms Infested fronds become curled or distorted, with silver-gray
scars or calloused areas where feeding has occurred.
Control Many materials are registered and effective at controlling
SAFE QUESTIONABLE UNSAFE
Bacillus Thuringiensis Pentac WP Dimethoate EC
Enstar 5E Mavrik Dursban EC
Kelthane EC Dylox LS
Metasystox-R EC Malathion EC
Orthene S Onite WP
Sevin WP Permethrin EC
Vydate L Plictran WP
Temik G Resmethrin EC
Pesticides were tested at recommended rates and intervals.
1. Chase, A. R. 1983. Phytotoxicity of some fungicides used on tropical
foliage plants. ARC-Apopka Research Report, RH-83-2.
2. Short, D. E. 1978. Phytotoxicity of insecticides and miticides to
foliage and woody ornamental plants. Extension Entomology Report #57.
3. Short, D. E., L. S. Osborne, and R. W. Henley. 1982. 1982-83 Insect
and related arthropod management guide for commercial foliage and woody
plants in Florida. Extension Entomology Report #52.
4. Simone, G. W. 1983. Fungicides for use on ornamentals 1983-84.
Extension Plant Pathology Circular 484-A.
Mention of a commercial or proprietary product or pesticide in this paper
does not constitute a recommendation by the authors nor does it imply
registration under FIFRA amended. Pesticides should be applied according
to the label instructions and safety equipment required on the label or by
federal law should be employed. Pesticides listed in the control sections
but not listed in the phytotoxicity charts HAVE NOT been tested for plant
safety by the University of Florida.