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
A. R. Chase, R. T. Poole and L. S. Osborne1
University of Florida, IFAS
Agricultural Research Center Apopka
ARC-A Foliage Plant Research Note RH-1983-B
Dieffenbachias, originally from Costa Rica to Colombia, are found in
many homes and offices. They are sturdy, thick-stemmed plants with colorful,
oblong, pointed, glabrous leaves which are generally green and cream colored.
There are many important species of Dieffenbachias. Dieffenbachia 'Exotica'
is an attractive compact plant with green leaves splashed with cream-white
blotches. Dieffenbachia amoena grows to be one of the largest Dieffenbachi s,
having deep green leaves with cream markings along the veins. -Dieffenbachia
maculata 'Rudolph Roehrs' has yellow or chartreuse leaves edged and centered.
with dark green. Other popular Dieffenbachia cultivars include Perfection,
Camille and Compacta.
Plants are best produced commercially under 1,500 to 3,000 foot-candles
(approximately 80% shade), and should be fertilized with a 3-1-2 (N-P205-K20)
ratio at a rate of 2.5 pounds of nitrogen per 1000 ft2 per month. Excellent
Dieffenbachias can be grown in a variety of potting media, but the media should
be well aerated and have low soluble salts to avoid root damage.
1) Excess soil moisture or soluble salts.
Symptoms Leaves are frequently curved downward, are small and sometimes
have necrotic (burned) edges. Severe root loss can also occur in the
absence of foliar symptoms when plants in a greenhouse are watered
frequently. Plants with poor root systems will not endure either
shipping or adverse interior conditions as well as those with good roots.
plant Pathologist, Physiologist and Entomologist, Agricultural Research Center,
Rt. 3, Box 580, Apopka, FL 32703, respectively.
Control Fertilizer additions should be monitored, and excess soluble
salts avoided. Leach to remove excess salts. Reduce irrigation
frequency if rooting medium stays too wet. Dieffenbachias with a
vigorous root system do not need frequent irrigations when grown
in a good potting mix.
2) Temperature induced foliage water-soaking
Symptoms Young leaves have a watery transparent appearance, generally
found during winter months.
Control This problem is usually temporary, developing when plants
are grown in high air temperatures and relatively low soil tempera-
tures. Roots do not absorb enough water to maintain proper water
balance in the leaves. Increasing soil temperature or reducing
air temperature will alleviate the situation.
3) Low humidity foliar chlorosis (yellowing)
Symptoms The lower leaves of plants are yellow. This occurs more
often in the propagation area than in stock areas.
Control Yellow leaves are often the result of excess moisture loss.
When plants with poor root systems are kept in a warm atmosphere,
the water balance is sometimes deficient and leaf chlorosis
occurs. Increase the humidity, especially in the propagating
area, to control this problem.
4) Cold temperature damage
Symptoms Areas between main veins become chlorotic or light brown
as a result of cold temperatures.
Control Prevent exposure to low temperatures. Avoid extreme or
abrupt changes in temperature. Although some Dieffenbachias can
be exposed to 450F without apparent leaf damage, plants grown in
high temperatures (70-950F) can be damaged if the temperature
suddenly plunges to 50F or below.
5) Improper growing conditions leading to leaf notching
Symptoms A small notch appears, usually on lower edge of leaf.
Control The exact cause is unknown, but notching seems to occur
when plants have been exposed to stress conditions, e.g.,
drought, high temperature, possibly improper pesticide application;
thus, these conditions should be avoided.
DISEASES OF DIEFFENBACHIAS
Dieffenbachias are subject to Dasheen mosaic virus, several serious
bacterial diseases, including Erwinia blight, and many diseases of stems,
leaves and roots caused by fungi. Perfection-type Dieffenbachias are the
most susceptible cultivars to many diseases. Control of fungal diseases
is possible in many situations through use of pesticides and cultural
methods. However, control of viral and bacterial diseases is best
achieved through use of pathogen-free stock obtained from tissue-cultured
plants and roguing diseased plants. The most common or serious diseases
of these plants are listed below.
MAJOR FUNGAL PATHOGENS
1) Anthracnose and brown leaf spot
Symptoms Symptoms of these two leaf spots are very similar, with
both occurring primarily during the cooler, winter months. Leaf
spots are initially tan and water-soaked and may have a bright
yellow halo. Fruiting bodies of the causal organism (Glomerella
or Colletotrichum spp., anthracnose or Leptosphaeria sp.- brown
leaf spot) appear in concentric rings of tiny black specks within
the leaf spot.
Control Keep foliage dry, especially from cold water drips due to
condensate. Many fungicides, such as Benlate and Manzate, are
labeled for use on Dieffenbachia and provide some control of these
2) Fusarium stem rot (Fusarium solani)
Symptoms Fusarium stem rot typically appears as a soft, mushy rot
at the base of a cutting or rooted plant. The rotten area
frequently has a purplish to reddish margin. Infection also occurs
on leaves under very wet conditions and results in tan, papery
leaf spots with concentric rings. Fusarium does not form the
black fruiting bodies seen in anthracnose or brown leaf spot, but
forms tiny, bright red, globular structures at the stem base of
severely infected plants.
Control Benlate is labeled and provides good control of both the
leaf spot and stem rot phases. If stem rot or cutting rot is a
problem, treatment of the cuttings with a dip or a post-sticking
drench of Benlate should diminish losses. Remove infected plants
from stock areas as soon as they are detected. Since Fusarium
stem rot appears similar to Erwinia blight, accurate disease
diagnosis is very important prior to applications of pesticides.
3) Myrothecium leaf spot (Myrothecium roridum)
Symptoms Myrothecium leaf spot most frequently appears on wounded
areas of leaves such as tips and breaks in the main vein which
occur during sticking. The leaf spots are watery and nearly always
contain the black and white fungal fruiting bodies in concentric
rings near the outer leaf spot edge. The presence of these bodies
is good evidence that the cause is Myrothecium. Newly planted,
tissue cultured explants are especially susceptible to this disease.
Control Benlate is registered on this plant but Daconil will also
provide good control although it is not labeled. Avoid wounding
leaves and keep the foliage as dry as possible. Many other plants
are hosts of M. roridum such as Aphelandra, Aglaonema, Begonia
and Spathiphyllum and these plants must be included in control
4) Phytophthora stem rot and leaf spot
Symptoms This disease occurs primarily on plants grown in or on the
ground in South Florida. Leaf spots are initially small and water-
soaked, with irregular margins. They may become tan and papery if
conditions are dry or their centers may fall out if conditions are
wet. Stem rot usually begins at the soil line where the stem
becomes soft and watery and lower leaves turn yellow. Eventually,
the area becomes sunken and a cavity may form and result in lodging.
Control Banrot, Terrazole, Truban and Subdue are labeled and should
provide control. Growing plants on raised benches, away from the
natural source of infection, is the best way to avoid this disease.
Due to similarities between this and several other diseases, diagnosis
must be confirmed by a creditable plant pathology laboratory before
optimum control strategies can be developed.
MAJOR BACTERIAL PATHOGENS
1) Erwinia blight and stem rot (Erwinia carotovora pv. carotovora and E.
Symptoms Stem rot and leaf spot caused by Erwinia spp. appears very
much the same as Fusarium stem rot and Phytophthora stem rot.
Rotted areas are usually watery and mushy and have a rotten fishy
odor in many cases. The bacterial sometimes form a slimy, gelatinous
mass at the base of infected cuttings and infected plants generally
have yellow lower leaves. Leaf spots caused by Erwinia spp. enlarge
rapidly and centers may become so watery that they fall out.
Control The only successful control of this disease is eradication
of all plants with symptoms. This should be done during the hot
months when Erwinia blight is most prevalent. Use of infected
plants that are not showing symptoms generally results in loss of
most of the cuttings since the bacterium is found inside the plant
stem (systemic). Only pathogen-free plants should be used as stock.
Agri-mycin and copper compounds may provide limited control of the
leaf spot symptom as well as keeping foliage dry to minimize new
infections. Many other foliage plants are susceptible-to this
bacterium and must be considered as potential sources of infection
MAJOR VIRAL PATHOGENS
1) Dasheen mosaic virus (DMV)
Symptoms Dasheen mosaic virus is most severe on 'Perfection' and
related cultivars of Dieffenbachia. Symptoms include mosaic, leaf
distortion and stunting and appear periodically during the year.
Control DMV is spread by both aphids and man. It is very important
to use pathogen-free stock since the symptoms of DMV are not
always noticeable. No chemicals have any known effects on this
virus disease. Other hosts such as Aglaonema, Philodendron and
Spathiphyllum must be monitored for symptoms, since they can act
as a reservoir of the virus.
PHYTOTOXICITY OF BACTERICIDES AND FUNGICIDES ON DIEFFENBACHIAS
Benlate 50 WP Agri-mycin
Captan 50 WP
Chipco 26019 50 WP
Daconil 2787 75WP and 4.17F
Pesticides were tested at recommended rates and intervals.
MAJOR INSECT AND MITE PESTS OF DIEFFENBACHIAS
The most serious pest which attacks Dieffenbachia spp. is-the two-
spotted spider mite. Plants can become infested with this pest at any time
during the year. Multiple applications of pesticides are needed if quality
plants are to be grown. There are other less serious pests which require
control but only when they are observed. In the control section for each
pest, some of the many registered and effective pesticides are listed. For
a complete listing, please consult the references listed at the end of this
Symptoms Aphids are pear-shaped, soft-bodied insects which vary in
color from light green to dark brown. Infestations may go undetected
until honeydew or sooty mold is observed. Aphids can cause distor-
tion of new growth or, in extreme cases, infested plants can be
stunted. The root systems of Dieffenbachia spp. are sometimes
infested with a small reddish aphid. This aphid (rice root aphid)
can be found by removing the plant from its container and inspecting
the roots with a hand lens.
Control Aphids are relatively easy to control with many registered
materials, i.e., Orthene, Vydate or Temik. Root aphids have been
controlled with soil drenches of Diazinon or Metasystox-R.
Symptoms Mealybug eggs appear as white, cottony masses in leaf axils,
on lower leaf surfaces and on roots. Honeydew and sooty mold are
often present and infested plants become stunted. With severe
infestations, plant parts die.
Control Mealybugs are difficult to control especially when they are
mature. Control measures should be aimed at killing this pest when
it is in the crawler stage. Systemic materials are preferred.
Examples of chemicals which have systemic activity are: Dimethoate,
Disyston, Metasystox-R, Orthene and Vydate. Bendiocarb appears to
be as effective as some systemic materials. Root infestations can
be controlled with soil drenches of Diazinon or Metasystox-R.
Symptoms Two-spotted spider mites are very small and go unnoticed
until plants begin to turn yellow or become speckled due to the
feeding of this pest. Webbing, loss of leaves and plant death can
occur when mite populations reach high levels.
Control Mites can be controlled with either Vendex or Pentac. The
critical point in any control program is thorough coverage with
the pesticide. The best control program is to minimize the possibil-
ity of introducing mites into the growing area on infested plant
Symptoms Infested plants become weakened or stunted and begin to die.
Scales can be found feeding on leaves, petioles, or stems. Their
shapes, sizes and colors are.variable.
Control See mealybugs.
Symptoms Curled or distorted leaves with silver-gray scars where
feeding has occurred.
Control Many materials are registered for thrips control.
PHYTOTOXICITY OF INSECTICIDES AND MITICIDES TO DIEFFENBACHIA
Safe Questionable Unsafe
Bendiocarb WP Dimethoate EC Morestan
Diazinon EC Malathion EC Volck Oil
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. 1982. Disease control pesticides for foliage production-
1982. Extension Plant Pathology Report #30.
Mention of a commercial or proprietary product or of a pesticide in this
paper does not constitute a recommendation by the authors, nor does it
imply registration under FIFRA as amended.