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COMMON BACTERIAL DISEASES OF FOLIAGE PLANTS
S. -* ": A. R. Chase
L LL I FASUri diversity of Florida
Agricultural Research Center-Apopka
ARCApopka Research Report RH-81-8
The -ree.ious. thrpearticles of this series have been concerned with fungal
diseases of foliage plants and were divided according to symptomatology. This
article discusses diseases caused by bacteria affecting both leaves and stems
of infected plants. In one respect bacterial diseases are more serious than
fungal diseases since there are few efficaceous chemicals for their control.
Most bacterial diseases caused by Pseudomonas and Xanthomonas spp. involve the
leaves of the plant, while stem rots primarily are caused by Erwinia spp.
Cultural control methods for bacterial diseases are much the same as those
recommended for foliar fungal diseases and revolve around keeping the foliage
dry. Bacterial disease is generally most severe during the summer. Use of
pathogen-free stock is absolutely necessary since many bacterial pathogens
are introduced in this way. Control tactics depend to some extent upon
whether or not the stem of the plant is involved since some leafspots can be
controlled through bactericide applications. It is, however, doubtful that
stem rot organisms are affected by these chemicals since the major pathogen
is systemic in plants and cannot be eradicated with bactericides. Thus, the
best way to control bacterial stem rot disease is avoidance since infected
plants must be discarded to avoid contamination of uninfected plants. Of
course, the best way to control any disease is avoidance of infection and
good sanitation and other cultural controls should be designed toward this
Assistant Professor of Plant Pathology, Agricultural Research Center, Rt. 3,
Box 580, Apopka, FL 32703.
As in the previous articles, specific diseases followed by numbers of
references giving additional information on that topic are discussed. Many
of the papers listed include valuable information on chemical control of these
diseases which are not included in this article. The table at the end of the
article gives the known hosts of each organism and the common name of the
disease it causes.
ERWINIA CAROTOVORA (2,7)
Erwinia carotovora is a serious stem rot organism for many foliage plants,
especially those rooted from cuttings. The bacterium can be present in cuttings
when they are taken from apparently healthy stock plants. Under warm, wet
conditions required for rooting of cuttings, the bacterium develops extensively,
and a rapid mushy rot develops with most infected cuttings lost. The source of
the bacterium also can be a cutting instrument which is contaminated during
cutting removal from an infected plant and transfers the bacterium to cuttings
made from healthy plants. As the number of cuttings being transported from
the tropics increases, the number of reports of soft rot also increases. Cut-
tings are frequently held in sealed containers for periods up to one week in
which humidity and temperature levels are ideal for development of decay
resulting in a complete loss of the plants. The use of pathogen-free stock
plants and sterile cutting instruments is recommended for control of this
type of disease. Other hosts of this pathogen include aglaonema, anthurium,
dracaena, kalanchoe and syngonium.
ERWINIA CHRYSANTHEMI (3,4,5,8,9,12,13,15,16,18,19,23,24)
Erwinia chrysanthemi was first isolated from chrysanthemum and since
then has been reported to cause many serious diseases of vegetable, flower
and foliage crops. E. chrysanthemi has an extensive host range in foliage
plants. Hosts include African violet, aglaonema, dieffenbachia, philodendron
and syngonium but many others are subject to this organism as well. E.
chrysanthemi causes both stem rots and leafspots depending somewhat on the
environmental conditions and the host. Diseases caused by E. carotovora
and E. chrysanthemi are very similar and both organisms can be involved
in the same disease. Stem rot of dieffenbachia is generally caused by E.
chrysanthemi but E. carotovora is equally isolated from infected tissue.
Bacterial leafspots caused by E. chrysanthemi are characterized by water-
soaking and collapse of the spot. Frequently, the entire spot will melt
away and leave a ragged edge. There are some indications that wounding is
necessary for the initiation of infection, but this is not always the case.
Bacteria are easily splashed by irrigation water or rainfall and require
free water on leaves for development and keeping the foliage dry is extremely
important in their control.
Bacterial stem rot of dieffenbachia is possibly the most serious dis-
ease of that plant. Initial symptoms of infection are chlorotic lower
leaves and wilting, especially apparent in propagation areas. Many infected
cuttings develop a mushy stem rot and collapse and in very wet conditions
infected leaves melt away. Leafspots caused by E. chrysanthemi are generally
dark and develop rapidly sometimes affecting the entire leaf blade and petiole.
If infected leaves and plants are not removed from stock or production areas,
other plants easily become infected through movement of water or workers.
PSEUDOMONAS ALBOPRECIPITANS (10)
Pseudomonas alboprecipitans causes leaf blight offishtail palm (Caryota
mitis). This disease is not as common as many of those discussed in this
article but can be serious. Initial symptoms of disease are translucent,
water-soaked lesions developing into necrotic streaks along the leaf veins.
Mature lesions often are surrounded by a chlorotic halo and the center is dark
brown or black. Control of this disease can be accomplished through removal
of infected leaves and maintaining dry foliage as much as possible. No other
palms have been reported as hosts of this organism but the possibility should
PSEUDOMONAS ASPLENII (1)
Pseudomonas asplenii was reported in 1946 as the cause of a bacterial
disease of Bird's-nest fern (Asplenium nidus) but does not appear to be
common today. Initial symptoms start as small watersoaked spots which are
translucent and appear usually on the upper leaf surface. Spots enlarge rap-
idly and can encompass the entire leaf. Since the symmetry of the plant is
important in plant quality, the loss of a single leaf can be serious. Strict
sanitation and maintenance of dry foliage are important in disease control.
PSEUDOMONAS CICHORII (20,22,27)
Pseudomonas cichorii causes leafspots of many plants including aglaonema,
anthurium, dracaena, gerbera, monstera, philodendron and pothos. Conditions
for development of this bacterial leafspot are the same as those described
for Erwinia chrysanthemi leafspot and control methods are also the same.
One of the most commonly seen diseases occurs on Dracaena sanderana and is
characterized by dark green watersoaked spots which later turn tan and have
a chlorotic border. The spots can enlarge until the entire leaf blade is
involved. This disease is especially prevalent in mist beds where cuttings
are rooted since the high humidity and temperature favor disease development.
Use of pathogen-free stock is an important method of control.
XANTHOMONAS DIEFFENBACHIAE (6,11,14,16,17,25,26)
Xanthomonas dieffenbachiae was first described on dieffenbachia. Circu-
lar, translucent spots develop on all areas of the leaf blade, later becoming
dull green with a yellow halo. Mature lesions are tan and irregular usually
retaining the yellow halo. As with other bacterial diseases, keeping the foliage
dry and removing infected leaves is important to control this disease. The first
report of this disease was made in 1939 and it was not until 1962 that the same
organism was recognized as causing a disease on another foliage plant, aglaonema.
Since then anthurium, philodendron, and syngonium have been added to the list of
plants susceptible to Xanthomonas dieffenbachiae.
The disease is very serious in Philodendron scandens oxycardium when plants
are grown in ground beds and exposed to rainfall or watered from overhead.
When conditions are dry and cool, symptom expression can be limited to a reddish
leaf edge while under warm wet conditions, the bacterium spreads into the center
of infected leaves and water-soaked lesions appear. Lesions are most easily
recognized on the lower surface of the leaf and are yellowish and frequently
bounded by the leaf veins.
XANTHOMONAS HEDERAE (28)
Xanthomonas hederae causes bacterial leafspot and stem canker of English
ivy and was described as early as 1894 although the identity of the pathogen
was not determined until 1934. Bacterial leafspot and stem canker of Hedera
helix (ivy) has continued to cause serious losses over the last 47 years.
Leafspots appear as small water-soaked areas which turn dark brown to black
and have a chlorotic halo. Mature lesions have a similar appearance to those
caused by Colletotrichum sp. and indeed both diseases may occur simultaneously
on a planting. Colletotrichum leafspot can be differentiated if the small
black fruiting bodies of the fungus are present in the lesions. Under warm
wet conditions lesions develop extensively and spread into the petiole and
stems. Infection of stems also occurs directly through the succulent new
growth. A soft, dark brown to black decay rapidly occurs in this tissue
and advances until older more mature tissue is reached. Control of this
disease should be accomplished using the same cultural controls as other
XANTHOMONAS SP. (21)
Two additional foliage plants have been reported as susceptible to an
unidentified Xanthomonas sp., Pellionia spp. and Pilea sp. Lesions have
water-soaked margins and tan centers which can fall out under wet conditions.
Heavily infected plants also can suffer leaf abscission (drop).
Common bacterial diseases of foliage plants listed
giving the pathogen.
according to host and
Host Disease Pathogen
African violet (See Saintpaulia)
Aglaonema spp. Soft rot
Bacterial leaf blight
i. Erwinia blight and
Rapid decay (soft rot)
and stem canker
Pseudomonas cichorii and
Pseudomonas cichorii and
ivy (See Hedera)
Kalanchoe spp. Soft rot
Monstera sp. Bacterial leafspot
Pellionia sp. Bacterial leafspot
Philodendron spp. Erwinia blight
Red edge (P. scandens
Pilea sp. Bacterial leafspot
pothos (See Epipremnum)
Saintpaulia ionantha Erwinia blight
Sansevieria spp. Soft rot
Syngonium spp. Soft rot
1. Ark, Peter A. and C. M. Thompkins. 1946. Bacterial leaf blight of bird's
nest fern. Phytopathology 36:758-761.
2. Brown, J. G. and Alice M. Boyle. 1944. Bacterial soft rot of sansevieria.
3. Dickey, Robert S. 1979. Erwinia chrysanthemi: A comparative study of
phenotypic properties of strains from several hosts and other Erwinia
species. Phytopathology 69:324-329.
4. Dickey, Robert S. 1981. Erwinia chrysanthemi: Reaction of eight plant
species to strains from several hosts and to strains of other Erwinia
species. Phytopathology 71:23-29.
5. Haygood, R. A. and D. L. Strider. 1979. Influence of temperature,
inoculum concentration, and wounding on infection of Philodendron selloum
by Erwinia chrysanthemi. Plant Disease Reporter 63(7):578-580.
6. Hayward, A. C. 1972. A bacterial disease of anthurium in Hawaii. Plant
Disease Reporter 56(10):904-908.
7. Knauss, J. F. and J. W. Miller. 1972. Description and control of the
rapid decay of Scindapsus aureus incited by Erwinia carotovora. Proc. Fla.
State Hort. Soc. 85:348-352.
8. Knauss, J. F. and J. W. Miller. 1974. Bacterial blight of Saintpaulia
ionantha caused by Erwinia chrysanthemi. Phytopathology 64(7):1046-1047.
9. Knauss, J. F. and J. W. Miller. 1974. Etiological aspects of bacterial
blight of Philodendron selloum caused by Erwinia chrysanthemi. Phyto-
10. Knauss, J. F., J. W..Miller and R. J. Virgona. 1978. Bacterial blight
of fishtail palm, a new disease. Proc. Fla. State Hort. Soc. 91:245-247.
11. Knauss, J. F., W. E. Waters and R. T. Poole. 1971. The evaluation of
bactericides and bactericide combinations for the control of bacterial
leaf spot and tip burn of Philodendron oxycardium incited by Xanthomonas
dieffenbachiae. Proc. Fla. State Hort. Soc. 84:423-428.
12. Knauss, J. F. and C. Wehlburg. 1969. The distribution and pathogenicity
of Erwinia chrysanthemi Burkholder et al. to Syngonium podophyllum Schott.
Proc. Fla. State Hort. Soc. 82:370-373.
13. Lai, Mingtan, Steven Shaffer and Ken Sims. 1978. Bacterial blight of
Syngonium podophyllum caused by Erwinia chrysanthemi in California.
Plant Disease Reporter 62(4):298-302.
14. McCulloch, Lucia and P. P. Pirone. 1939. Bacterial leaf spot of
dieffenbachia. Phytopathology 29:956-962.
15. McFadden, Lorne A. 1961. Bacterial stem and leaf spot of dieffenbachia
in Florida. Phytopathology 51:663-668.
16. McFadden, Lorne A. 1962. Two bacterial pathogens affecting leaves of
Aglaonema robelinii. Phytopathology 52:20.
17. McFadden, L. A. 1967. A Xanthomonas infection of Philodendron oxycardium
leaves. Phytopathology 57:342.
18. McFadden, Lorne A. 1969. Aglaonema pictum, a new host of Erwinia
chrysanthemi. Plant Disease Reporter 53:253-254.
19. Miller, H. N. and Lorne A. McFadden. 1961. A bacterial disease of
philodendron. Phytopathology 51:826-831.
20. Miller, J. W. and J. F. Knauss. 1973. Bacterial blight of Gerbera
jamesonii incited by Pseudomonas cichorii. Plant Disease Reporter
21. Miller, J.W., R. J. Virgona and J. F. Knauss. 1976. Xanthomonas leaf
spot of Pellionia pulchra, P. daveauana and Pilea cadierei. Proc. Amer.
Phytopath. Soc. 3:340-341.
22. Miller, J. W. and C. Wehlburg. 1969. Bacterial leaf spot of Dracaena
sanderiana. Proc. Fla. State Hort. Soc. 82:368-370.
23. Munnecke, Donald E. 1960. Bacterial stem rot of dieffenbachia. Phyto-
pathology 50 (10):696-700.
24. Roberts, Betty J. 1977. Susceptibility of certain Saintpaulia species
and cultivars to bacterial blight. Plant Disease Reporter 61(12):1048-
25. Wehlburg, C. 1968. Bacterial leaf spot and tip burn of Philodendron
oxycardium caused by Xanthomonas dieffenbachiae. Proc. Fla. State
Hort. Soc. 394-397.
26. Wehlburg, C. 1969. Bacterial leaf blight of Syngonium podophyllum.
27. Wehlburg, C., C. P. Seymour and R. E. Stall. 1966. Leaf spot of araceae
caused by Pseudomonas cichorii (Swingle) Stapp. Proc. Fla. State Hort.
28. White, Richard P. 1934. A bacterial disease of Hedera helix. Journal
of Agricultural Research 48(9):807-815.