Group Title: ARC-A research report - Agricultural Research Center-Apopka ; RH-81-5
Title: Common fungal leaf spot diseases of foliage plants
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00065949/00001
 Material Information
Title: Common fungal leaf spot diseases of foliage plants
Series Title: ARC-A research report
Physical Description: 17 leaves : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Agricultural Research Center (Apopka, Fla.)
Publisher: IFAS, University of Florida, Agricultural Research Center-Apopka
Place of Publication: Apopka Fla
Publication Date: 1981
 Subjects
Subject: Foliage plants -- Diseases and pests -- Florida   ( lcsh )
Leaf spots -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaves 15-17).
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065949
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70921966

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








S Common Fungal Leafspot Diseases of Foliage Plants

A. R. Chase
IFAS, University of Florida ",
Agricultural Research Center Apopka /
ARC-A Research Report RH-81-5
lF Univ. of F;rii da
Diseases of foliage plants are commonly a limiting factor in profitatiT "
plant production in Florida. Some diseases occur frequently on a wide variety
of hosts while others occur only occasionally on one or a few hosts. Regardless
of the frequency, most diseases present typical, easily identified symptoms
in affected plants. Recognition of the commonly occurring diseases is an
important step toward effective economical disease control. This article is
the first of a series that will discuss the most common diseases of foliage
plants in Florida. These articles will deal with five disease types based on
the kind of organism involved and the location on the host that the organism
attacks. The following are the five disease types: 1) fungal leafspots;
2) fungal stem rots; 3) fungal root rots; 4) bacterial diseases; and 5) viral
diseases. At the end of each article a table has been included listing the
major diseases of each plant discussed.
All fungal leafspots, although caused by a wide variety of fungi have
one major factor in common. They require free water on leaves or high humidities ..
to develop. Thus, the most important control measure of this group of diseases
is keeping the foliage dry. This is most easily accomplished by growing plants
in enclosed structures and watering them by a method which delivers water only ..
to the potting media and the roots. Studies at the ARC-Apopka demonstrate the
effect of water on leafspot severity. Alternaria leafspot of scheffleras was
reduced from 50 to 100% in plants watered at the soil level compared to plants
watered by overhead irrigation. The importance of this control method cannot :
be stressed too highly! In all cases, the need for chemical sprays for leafspot








control will be minimized and in some instances eliminated entirely.
The following paragraphs deal with specific fungal leafspots of foliage
plants and will include pertinent information regarding symptoms of the
leafspot, the plants which it is known to infect and references to additional

literature concerning those diseases (in parentheses following each heading).

This will help growers diagnose common diseases of their plants and determine

appropriate control methods.
ALTERNARIA (22)

Alternaria leafspot is the most common disease of Brassaia actinophylla

(schefflera), especially when the plants are grown exposed to rain. Lesions

range in size from pin points to 5 cm (2") or more. They are generally
dark-brown to black and may have a watersoaked appearance. A yellow halo
can be seen surrounding many of the spots. Lesions may develop on the petioles

and even on the stems of infected plants. Large spots can be surrounded by

smaller spots which were created by water splashing spores from the central
spot over the leaf surface. Severe infections result in considerable leaf
drop. Alternaria leafspot occurs throughout the year, although it is most

severe during warm!wet weather. Scheffleras are typically very sensitive to

pesticide injury so it is especially important to keep the foliage dry and avoid
chemical sprays. In addition to scheffleras, many species of Polyscias and
Fatsia have been infected by Alternaria sp. causing similar spots.
BOTRYTIS (1,4)

The most important host of Botrytis sp. is Saintpaulia ionanthd (African

violet). This disease has been present on African violet since the 1940's
and continues to cause severe losses today. Botrytis is usually a pathogen
of flowering plants and it does indeed cause a flower blight of African violet.








It also causes a leaf blight characterized by small watersoaked lesions

starting on petioles in contact with the pot rim. Spots enlarge rapidly

and may encompass the entire leaf blade which eventually becomes black.

Spots may start in the center of leaf blades when infected flowers drop

onto them. The fruiting structures of Botrytis can be readily seen on

infected leaves as dusty masses of gray-brown spores. One of the keys to

control of this.disease is removal of damaged leaves to eliminate the

introduction of the fungus into the plant and to maintain a vigorously
growing plant.
The same fungus causes a disease of Ficus elastica. Leafspots develop
in the youngest leaves and are tan to brown with concentric rings. The

newly emerging leaf may be infected and show black spots under the leaf

sheath. As with Botrytis blight of African violet keeping the humidity low
and removing diseased leaves can reduce disease severity.
Many other foliage plants have been reported as hosts of Botrytis sp.,

including Aeschynanthus, Dracaena, Hoya and Hedera. In general the most

susceptible plant parts are flowers, immature leaf tissue and leaves in

contact with the soil. Botrytis is most prevalent during the cooler winter

months and special care should be taken then to prevent an outbreak.

CEPHALOSPORIUM-(3,15,16)

Cephalosporium has not been a serious pathogen of most foliage plants.

The most important host of Cephalosporium sp. is Syngonium spp. nephthytiss).
This leafspot occurs during the warm wet months and is most often serious on
plantings of syngonium grown in ground beds outdoors. Leafspots are small
and generally have a reddish brown to yellow border. Leafspots may become

very numerous giving the leaves the appearance that they have been shot with




-4-


a shotgun, thus the common name of the disease "Shotgun fungus". Infection

is most severe on the youngest leaves and they should be kept dry at all times.

Improvements in growing conditions of syngonium have greatly reduced the

occurrence of Shotgun fungus. In addition to syngonium, Dieffenbachia spp.

are susceptible to the same fungus. Again, the youngest leaves are the most

susceptible and infections appear as tiny reddish brown circular to elongate

lesions. As spots enlarge the centers turn grayish brown. The same control
tactics should be used to prevent the disease on syngonium and dieffenbachia.

CERCOSPORA (2,18,19,29)

Cercospora leafspot has been found on numerous species of foliage plants.

Since it may seem similar to a physiological condition such as edema, diagnosis

of this disease is often difficult. Specific diseases caused by Cercospora have
been described on Peperomia spp., Ficus sp. and Kalanchoe sp. although records

show many other hosts including Brassaia spp. Generally symptoms produced by

Cercospora spp. are slightly raised pinpoint swellings on the underside of

leaves. In Ficus elastica these swellings become tan to brown and the area

may be surrounded by a yellow halo. Severely infected leaves become chlorotic

and abscise. In contrast, the Cercospora leafspot of Kalanchoe sp. is typified

by sunken lesions which are purplish-brown when young and tan as they develop.

As with the ficus, the leaves may drop early when they are severely infected.
Symptoms of Cercospora leafspot of Brassaia spp. (especially B. arboricola)
are tiny purple spots on leaf undersides. Tan centers can develop as they

enlarge and the upper leaf surface appears chlorotic. Controlling Cercospora

leafspots is based upon keeping the foliage dry and allowing adequate air space

around plants to lower relative humidity.
COLLETOTRICHUM (7,8,12,24,26,30)

Colletotrichum and Gloeosporium spp. are frequently isolated from

leafspots of foliage plants. They are considered the same organism by most




-5-


mycologists and I have grouped diseases caused by both fungi under the

same title. The list of susceptible plants includes: Aglaonema,

Araucaria, Cryptanthus, Dieffenbachia, Dionaea, Dracaena, Ficus, Hedera,

Monstera, Peperomia, Philodendron, Pilea, and Syngonium. The most important

diseases in Florida occur on Araucaria heterophylla, Hedera helix, and

Dieffenbachia maculata.

Colletotrichum needle necrosis of Araucaria sp. (Norfolk Island pine)

occurs primarily on newly developing needles and appears as tan to brown

areas frequently accompanied by black fungal fruiting structures. Needle

infection requires either very high humidities or wet foliage and control is

based on keeping the foliage dry. This is especially important in seedling

beds since seedlings are most susceptible to Colletotrichum.

Glomerella leafspot of Dieffenbachia spp. is quite common during the
cooler months in Florida when plants are exposed to rainfall or overhead

irrigation. Glomerella is the name for the perfect stage of Colletotrichum

and Gloeosporium and may be considered a closely related organism. Glomerella

leafspot appears anywhere on the leaf surface as very small watersoaked

lesions. Spdts enlarge and become papery and tan in color if allowed to dry.
The borders are frequently yellow and can contain the fungal fruiting structures.

If wet conditions continue, the spots can enlarge to 1-2 cm and the dead

tissue in the center can fall out.

Colletotrichum leafspot of Hedera helix (Engli.sh ivy) is frequently

encountered in the winter months. As with the majority of diseases caused by

this organism, the lesions are dark brown to black and contain fruiting

bodies of the fungus. Lesions appear on leaves and petioles and can be severe

enough to kill large areas of the plant. Lesions may reach 1 cm in size when

wet conditions prevail. This disease is confused with Rhizoctonia aerial

blight of the same plant but is distinguished by the fruiting bodies and by




-6-


the absence of coarse brown hyphae on stems of infected plants (discussed

later).

CONIOTHYRIUM (27,32)

Brown leafspot of Yucca aloifolia (soft-tipped yucca) is caused by

Coniothyrium sp. The perfect stage of this fungus is Leptosphaeria which

also is isolated frequently from these spots. Spots begin as dark brown to

black elliptical lesions on lower leaves becoming depressed with age and

tan centers and wide purplish margins. Concentric zones of black and light

brown tissue can be seen in mature spots. Removal of lower leaves with

severe leafspot can reduce spread to upper leaves.

CORYNESPORA (21)

Corynespora leafspot of Aphelandra squarrosa (zebra plant) can be

controlled by avoiding wounding of leaves, since this fungus is primarily a

wound pathogen. Dark brown to black lesions appear most commonly on lower

leaves in contact with the soil starting on the edge of the leaf or in the

center. The spots may reach 1 cm in diameter. In most cases this disease

does not cause serious losses in aphelandra production and can be controlled
by avoiding rough handling of the plants and removal of diseased leaves as

they appear. Another susceptible plant is Aeschynanthus sp. (lipstick vine).

Leafspots appear purplish-red with tan centers and again are found on lower

leaves.

CURVULARIA- (23)

Curvularia or tan leafspot of Rhoeo discolor (oyster plant) is typified

by tan sunken lesions. In early stages spots appear greenish and are small

and generally on leaf undersides. As they mature they become tan and can

coalesce to form irregularly shaped spots. In severe infections leaves become








distorted. Reduction in wetting foliage is an important means of control.

CYTOSPORINA (32)

Gray leafspot of Yucca sp. is caused by Cytosporina sp. and differs

from brown leafspot (Coniothyrium) of yucca in the size and color of the

lesions. The leafspots are generally gray with a brown border and may

reach a size of 7 cm. Spots form on leaf tips and margins. As with brown

leafspot this disease occurs most frequently on lower leaves and the same

control procedures are recommended.

DACTYLARIA (14)

Dactylaria leafspot of Philodendron scandens oxycardium is prevalent

in stock beds during the warm wet season. Initial leaf symptoms appear
as tiny watersoaked areas on both surfaces of young leaves. As leaves
mature lesions become yellow to tan and are slightly depressed. As with

Cephalosporium leafspot of syngonium,this disease has decreased in importance

as the stock beds of philodendron have been moved off the ground and placed

in enclosed structures.

FUSARIUM (10,33)

Fusarium leafspot is the most serious disease of Dracaena marginata and

occurs on most other species of Dracaena as well as pleomeles and sansevierias.

Infections occur only in the whorl on immature leaves, appearing initially
as pinpoint watersoaked lesions which generally escape notice. They enlarge

and become irregularly shaped with reddish centers and a yellow halo. The

disease is commonly called red leafspot on sansevierias due to the color

of the spots. When conditions are warm and wet the cream colored spores of
the fungus appear in lesions and are spread by splashing water to other plants.
In the most severe cases the entire meristem of the plant is rotted. This

disease can be controlled by eliminating overhead watering and exposure to rain.








HELMINTHOSPORIUM (20)

This fungus (also called Bipolaris, Drechslera and Exosporium)
causes several serious diseases on foliage plants in Florida, although

little research has been published to describe them. The most important

diseases occur on Aechmea fasciata (bromeliad), Chrysalidocarpus lutescens

(areca palm) and many other palms, Maranta leuconeura (prayer plant) and
Calathea spp.

The only adequately described disease is Helminthosporium leafspot of
Aechmea sp. This leafspot begins as tiny watersoaked spots which become
brown and have sunken centers and may have a yellow margin. Under optimum
conditions for disease development, the spots coalesce to form large brown

watersoaked areas and can result in leaves hanging limply from the plant.

Under low humidities spots cease to develop.
Helminthosporium leafspots of palms, especially areca palms, can be
serious under certain growing conditions. The most susceptible palm is
areca, although the following genera are susceptible also: Caryota,

Chamaedorea spp:., Kentia, Phoenix, and Raphis. Leafspot causedby

Helminthosporium spp. can occur on any leaf and is characterized by small

elliptical reddish-brown lesions frequently surrounded by a yellow halo. In
severe infections the leaf.may be covered by numerous spots which coalese to

form irregularly shaped areas. Infections of the immature leaf can result in

blight of that leaf, which subsequently may expand slightly or remain
unexpanded. Tips of pinnae may remain intact or shredded depending upon
disease severity and environmental conditions. Spots also have been seen on.
petioles although this is rare. Certain Helminthosporium spp. create a yellow

halo around the central spot which extends for 1-2 cm from the spot along the

leaf veins. Nutrition of the host plant appears to play a role in the severity








of the leafspot. Although the precise effect remains undetermined, plants

under poor nutrition seem to be more susceptible to this leafspot. Older

plants appear to be more resistant than younger plants, and as always,

control should be based on growing a nonstressed plant and keeping the

foliage dry.

Helminthosporium leafspot of marantas and calatheas can be severe during

the warm wet summer months. The infection in calatheas is characterized by
large irregularly shaped tan to dark brown spots. Spots can enlarge to
2 cm in diameter. Helminthosporium leafspot of maranta differs in the size

of the lesion, which is generally less than 2 mm in diameter. The color of the

spots is tan and they appear to be more numerous on affected leaves than
those on calatheas. This disease is most severe when plants are grown in
ground beds and exposed to rainfall. In this situation even chemical sprays
can be ineffective.

LEPTOSPHAERIA (17)

Brown leafspot of Dieffenbachia spp., caused by Leptosphaeria sp., is

quite similar to'Glomerella leafspot and is easily confused with that disease.

It is more prevalent during the cooler winter months and depends upon free

water on the leaves to develop and spread. The symptoms of brown leafspot

are lesions from pinpoint size to 3 cm (1") and are brown to grayish in

coloration. When the lesions are new they appear yellow and are watersoaked.

Lesions appear on leaf blades, petioles, stems and even on the flower spathes.

Severely infected leaves turn yellow and die. Control is the same as for

Glomerella leafspot.
MYROTHECIUM (None)

Myrothecium leafspot of Aphelandra sp. is similar in several ways to
Corynespora leafspot of the same plant. MyrotQecium sp. is a wound pathogen





-10-


and generally appears on the lower foliage touching the soil. The

appearance of the leafspot differs in that the spots are tan to dark black
and almost always have the black and white fruiting bodies of the

pathogen in the lesion. Myrothecium leafspot occurs on other species of

foliage plants and can be easily diagnosed by isolation of the pathogen

and by observation of the characteristic fruiting bodies. Myrothecium

leafspot also occurs on many other foliage plants including Pilea and

Aeschynanthus spp. Control of this disease is the same as for Corynespora

leafspot.
PHYLLOSTICTA (6)

Phyllosticta leafspot and blight of Dracaena sp. (formerly cordyline)

occurs primarily on older.leaves. Infection begins as a yellow area later

turning brown with a purple margin and frequently a yellow halo. In severe
infections spots coalesce and the leaf may die. The fruiting bodies of the
fungus form in concentric rings within the lesions and appear as tiny black

specks. Removal of infected leaves from the base of the plant is an

important control measure.

PHYTOPHTHORA (9,25,31,34,35)

Phytophthora leafspot is a serious disease on many of the most widely

grown foliage plants. This disease, like most foliar diseases, is most

severe in the warm wet months of the summer especially when plants are grown

in ground beds exposed to rainfall. Some of the hosts of this organism are

Brassaia sp., Dieffenbachia spp., Dracaena sp. (cordyline), Hedera sp., and
Philodendron spp. (especially P. scandens oxycardium).

The first report of this disease was made on P. scandens oxycardium

in 1963 by McFadden. Symptoms of Phytophthora leafspot include watersoaked

lesions of irregular shape beginning usually on the edges of ground beds. If




-11-


spots dry they appear papery and tan in color, but if wet conditions

prevail the spots continue to develop and their centers may become so wet

.that they fall away. As the stock beds of philodendron have been moved
to raised benches away from native soil (the presumed source of the

pathogen) this disease has decreased in its importance. Nutritional

studies have shown that use of more than the optimum amount of nitrogen

can reduce the severity of this disease on philodendron.

Phytophthora leafspot of schefflera is characterized by dark brown

watersoaked leafspots on lower leaves. The source of the pathogen is

thought to be the native soil and control should be based on placing a bar

between the soil and the plants.
Phytophthora leafspot of cordyline (ti plant) is also characterized by

large watersoaked irregularly shaped lesions. Infection usually occurs on

the lower leaves of plants exposed to water splash from the soil.

Leaf and stem blight of Hedera helix (English ivy) is caused by

P. palmivora, and affects both leaves and stems. Dark brown to black,

irregular spots and blights of leaves and blights of new shoots are symptoms
of this disease. This disease develops rapidly and may encompass an entire

leaf in 48 hours under favorable conditions. Control of this disease should

include use of sterile potting media and pots since the pathogen lives in
the soil.
RHIZOCTONIA (11,13)

Rhizoctonia solani causes seedling damping off in many foliage plants

but it is also an important cause of aerial blights. Susceptible plants

include most seedlings (schefflera, philodendron, syngonium) as well as
mature plants. Rhizoctonia aerial blight is most serious in the warm wet

months and may not appear at all during cool winter months unless plants are





-12-


grown under mist. Rhizoctonia blight is very important on syngonium,

ferns and English ivy. One of the most important keys toward diagnosis

of this disease is the presence of "spiderweb-like" reddish-brown strands of

the fungus. Lesions caused by this fungus are often tan to black and

appear watersoaked. In severe infections, the entire plant may become

blighted and brown and covered with strands of the fungus. Use of sterile

potting media, pathogen-free plants and maintaining water at low levels

can help control this disease. Since the pathogen requires high humidities

to develop, keeping the plants spaced widely to promote rapid drying of the

foliage is important.

SPHAEROBOLUS (5)

This organism is not a pathogen of foliage plants but is so common
that it bears'discussion here. The tiny fruiting bodies of "Shotgun fungus"
are produced in the potting media and fired onto plant leaves where they

stick and detract substantially from their appearance. The small mustard

seed sized bodies are black and can be removed by scraping. Sphaerobolus

lives in potting medium and appears to develop best under wet conditions
and keeping the soil moisture level low can help control this problem.

STEMPHYLIUM (28)

Stemphylium leafspot is not a serious disease of most foliage plants

but has been reported to cause losses in Kalanchoe, Echeveria, and Sedum spp.

Lesions form on both leaf surfaces and appear raised and wartlike with age.
They are generally dark brown to black and up to 3 mm in diameter. In some

plants several lesions coalesce and create irregularly shaped spots and

severe infections may result in chlorotic leaves and leaf abscission. On

some cultivars of kalanchoe, spots are larger and have a purple border.








-13-


Control of this leafspot should be based on elimination of overhead watering

which spreads the spores of the fungus and provides optimum conditions for

the development of the disease.


Summary of leafspot diseases caused by fungi


Host


Disease


Pathoaen


Aechmea fasciata
Aeschynanthus


Aphelandra squarrosa

Araucaria heterophylla
areca palm
Brassaia actinophylla
and other spp.



bromeliad
Calathea spp.
Chrysalidocarpus
lutescens and many
other palms
cordyline
Dieffenbachia spp.






Dionaea muscipula
Dracaena spp.



Fatsia japonica
Ficus elastica


Helminthosporium leafspot
Botrytis blight
Corynespora leafspot
Myrothecium leafspot
Corynespora leafspot
Myrothecium leafspot
Colletotrichum needle blight
(see Chrysalidocarpus)
Alternaria leafspot
Cercospora leafspot
Phytophthora leafspot

Rhizoctonia blight
(see Aechmea)
(see Maranta)


Helminthosporium leafspot
(See Dracaena)
Cephalosporium leafspot
Glomerella leafspot

Brown leafspot
Phytophthora leafspot

Colletotrichum leafspot


Botrytis blight
Fusarium leafspot
Phyllosticta leafspot (ti
Phytophthora leafspot (ti
Alternaria leafspot
Gray mold
Cercospora leafspot


plant)
plant)


H. rostratum
B. cinerea
C. cassiicola
M. spp.
C. cassiicola
I. spp.
C. derridis

A. actinoohvlla
-. spp.
P. parasitica var.
nicotianae
R. solani





H. spp. and others


C. cinnamomeum
G. cingulata
(Colletotrichum
sPP.)
Leptosphaeria sp.
P. parasitica var.
nicotianae
C. gloeosporioides
B. cinerea
F. rronifi~orme
P. draconis
7. parasifTca
A. actinophylla
Botrytis cinerea
C. sp.








-14-


Host


Disease


Hedera helix



Hoya spp.
Kalanchoe spp.

Maranta leuconeura
Nephrolepis exaltata
and other ferns
nephthytis
Peneromia spp.
Philodendron spp.


Pilea muscosa and
other spp.

Pleomele spp.
Polyscias spp.
Rhoeo discolor ;-
Saintpaulia ionantha

Sansevieria spp.
Synonium spp.

Yucca aloifolia


Botrytis blight
Colletotrichum leafspot
Phytophthora leafspot
Rhizoctonia blight
Botrytis blight
Cercospora leafspot
Stemohylium leafspot
Helminthosporium leafspot


Rhizoctonia blight
(See Syngonium)
Cercospora leafspot
Dactylaria leafspot (P. scandens
oxycardium)
Phytophthora leafspot

Rhizoctonia blight

Colletotrichum blight
Myrothecium leafspot
(See Dracaena)
Alternaria leafspot
Tan leafspot
Botrytis leaf and flower
blight
Red leafspot
Cephalosporium leafspot
Rhizoctonia blight
Brown leafspot


Gray leafspot


Pathoqen


cinerea
trichellu m
palmivora
solani
cinerea
sp.
bolicki
sp.


R. solani


C, sp.


humicola
parasitica var.
nicotianae
solani


capsi ci
spp.


A. actinophylla
Curvularia eraqrostidis

B, cinerea
Fusarium moniliforme
C. cinnamomeum
R. solani
Coniothyrium
concentricum
Cytosporina sp.


_ _


. U.
* ^






-15-

Literature Cited


1. Alfieri, S. A., Jr. 1966. Gray mold disease of Ficus. Fla. Dept. Agric.,
Div. Plant Ind., Plant Pathol. Circ. 45. 2 pp.

2. Alfieri, S. A., Jr. 1968. Cercospora and edema of Peperomia. Proc. Fla.

State Hort. Soc. 81:388-391.

3. Alfieri, S. A., Jr. and C. Wehlburg. 1969. Cephalosporium leafspot of

Syngonium podophyllum Schott. Proc. Fla. State Hort. Soc. 82:366-368.

4. Beck, G. E. 1949. Botrytis leaf and blossom blight of Saintpaulia.

Phytopathology 39:1054-1056.

5. Birchfield, W., J. L. Smith, A. Martinez and E. P. Matherly. 1957.

Chinese evergreen plants rejected because of global masses of Sphaerobolus
stellatus on foliage. Pl. Dis. Reptr. 41(6):537-539.

6. Desai, M.-V. and K. P. Patel. 1961. Leaf blight of Dracaena incited by

Phyllosticta draconis. Dept. of Plant Path. Inst. of Agric., Anand, India

45(3):203.

7. Garren, K. H. 1946. A disease of English ivy in Georgia. Pl., Dis..

Reptr.. 30(6):209-210.

8. Graham, S. 0. and J. W. Strober. 1958. Incidence of Anthracnose fungi on

ornamental foliage in Washington State greenhouses. Pl. Dis. Reptr. 42(11):

1294-1296.

9. Harkness, R. W. and J. E. Reynolds. 1964. Effect of nitrogen and potassium

nutrition on phytophthora leafspot of Philodendron oxycardium. Fla. State

Hort. Soc. 77:475-480.

10. Jones, L. K. 1949. Fusarium leafspot of Sansevieria. Phytopathology
30:527-530.
11. Knauss, J. F. 1971. Rhizoctonia blight of 'Florida Ruffle' fern and its

control. Pl. Dis. Reptr. 55(7):614-616.







-16-


12. Knauss, J. F. 1972. Foliar blight of Dionaea muscipula incited by

Colletotrichum gloeosporioides. Pl. Dis. Reptr. 56:394-397.

13. Knauss, J. F. 1973. Rhizoctonia blight of syngonium. Fla. State Hort.

Soc. Proc. 86:421-424.

14. Knauss, J. F. and S. A. Alfieri, Jr. 1970. Dactylaria leafspot, a new

disease of Philodendron oxycardium 'Schott'. Proc. Fla. State Hort. Soc.
83:441-444.

15. Linn, M. B. 1940. Cephalosporium leafspot of two aroids. Phytopathology

30:968-972.

16. Linn, M. B. 1942. Cephalosporium leafspot of Dieffenbachia. Phytopathology

32:172-175.
17. Marlatt, R. B. 1966. Brown leafspot of Dieffenbachia. Pl. Ois. Reptr.
50:687-689.

18. Marlatt, R. B. 1970. Isolation, inoculation, temperature relations and

culture of a Cercospora pathogenic to Efics elastica 'Decora'. Pl. Dis.
Reptr. 54:199-202.

19. Marlatt, R. B. 1972. Inoculation, incubation and abscission of Ficus

elastica foliage with Cercospora disease, P1. Dis. Reptr. 56:1091-1103.

20. Marlatt, R. B. and J. F. Knauss. 1974. A new leaf disease of Aechmea
fasciata caused by Helminthosporium rostratum. P1. Dis. Reptr. 58:445-448.

21. McRitchie, J. J. and J. W. Miller. 1973. Corynespora leafspot of Zebra

plant. Proc. Fla. State Hort. Soc. 86:389-390.

22. Miller, H. N. 1957. An Alternaria leafspot of Schefflera actinophylla.

Phytopathology 47:529. (Abstr.)
23. Miller, J. W. 1971. Tan leafspot of Rhoeo discolor caused by Curvularia

eragrostidis. P1. Dis. Reptr. 55(1):38-40.






-17-


24. Ridings, W. H. 1973. Colletrotrichum needle necrosis of Norfolk Island

pine. Proc. Fla. State Hort. Soc. 86:418-421.

25. Ridings, W. H. and J. J. McRitchie. 1974. Phytophthora leafspot of

Philodendron. Fla. Flower Grower 11:(12):5-6.

26. Saksena, H. K. 1960. Blight of Pilea muscosa caused by Colletotrichum

capsici. Pl. Dis. Reptr. 44(9):697.
27. Sobers, E. K. 1967. The perfect stage of Coniothyrium concentricum on

leaves of Yucca aloifolia. Phytopath. 57:234-235.

28. Sobers, E. K. and C. P. Seymour. 1963. Stemphylium leafspot of Echeveria.

Kalanchoe and Sedum. Phytopath. 53(12):1443-1446.

29. Spencer, J. A. 1973. A new Cercospora leafspot of Kalanchoe. Phytopath.

63:449. (Abstr.)

30. Strobel, J. W. and S. 0. Graham. 1960. Some physiologic responses of

Glomerella cingulata to various media and growth substances. Phytopath.

50:86. (Abstr.)

31. Trujillo, E. E., A. M. Alvarex, and D. N. Swindale. 1975. Phytophthora

leafspot of Ti. P1. Dis. Reptr. 59(5):452-453.

32. Wehlburg, C. 1969. Two leaf diseases of Spanish bayonet. Fla. Dept.

Agric., Div. Plant Ind., Plant Pathol. Circ. 79. 2 pp.

33. Wehlburg, C. and A. P. Martinez. 1967. Leafspot of Dracaena marginata

Lam. caused by Fusarium moniliforme Sheld. and its control. Proc. Fla.

State Hort. Soc. 80:454-456.

34. Wisler, G. C., W. H. Ridings and R. S. Cox. 1978. Phytophthora leafspot

of Brassaia actinophylla. Proc. Fla. State Hort. Soc. 91:240-242.
35. Uchida, J. Y. and M. Aragaki. 1978. Leaf and stem blight of ivy caused

by Phytophthora palmivora. Hawaii Agric. Exp. Sta. Jr. Series No. 2220.

62(8):699-701.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs