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 Front Cover
 Physiological problems
 Diseases of dieffenbachias and...
 Major bacterial pathogens
 Major viral pathogens
 Reference






Group Title: ARC-A foliage plant research note - Agricultural Research and Education Center - RH-1983-B
Title: Dieffenbachias
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00066498/00001
 Material Information
Title: Dieffenbachias
Series Title: ARC-A foliage plant research note
Physical Description: 10 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Poole, R. T ( Richard Turk )
Osborne, L. S
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1983
 Subjects
Subject: Dieffenbachia -- Growth -- Florida   ( lcsh )
Dieffenbachia -- Diseases and pests -- Florida   ( lcsh )
Dieffenbachia -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 10).
Statement of Responsibility: A.R. Chase, R.T. Poole and L.S. Osborne.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066498
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 71224432

Table of Contents
    Front Cover
        Front Cover
    Physiological problems
        Page 1
        Page 2
    Diseases of dieffenbachias and major fungal pathogens
        Page 3
        Page 4
    Major bacterial pathogens
        Page 5
    Major viral pathogens
        Page 6
        Page 7
        Page 8
        Page 9
    Reference
        Page 10
Full Text





HISTORIC NOTE


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
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




DIEFFENBACHIAS
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.
PHYSIOLOGICAL PROBLEMS

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

diseases.

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

programs.

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.

chrysanthemi)

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

for Dieffenbachia.


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

Safe Questionable

Benlate 50 WP Agri-mycin
Captan 50 WP
Chipco 26019 50 WP
Copper compounds
Daconil 2787 75WP and 4.17F
Manzate
Subdue 2E
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

report.

1) Aphids

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.

2) Mealybugs

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.

3) Mites

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

material.

4) Scales

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.

5) Thrips

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
Dipel Omite
Dursban EC
Dylox LS
Enstar
Kelthane EC
Lannate
Metasystox-R EC
Orthene S
Pentac WP
Permethrin
Plictran
Resmethrin EC
Sevin WP
Temik G
Thuricide EC
Vendex WP
Vydate EC

Pesticides were tested at recommended rates and intervals.






References

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.




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