Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-93-11
Title: Bacterial leaf spot and blight of Calatheas
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Permanent Link: http://ufdc.ufl.edu/UF00065830/00001
 Material Information
Title: Bacterial leaf spot and blight of Calatheas
Series Title: CFREC-Apopka research report
Physical Description: 2 p. : col. ill. ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, IFAS, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1993
 Subjects
Subject: Calathea -- Diseases and pests -- Florida   ( lcsh )
Bacterial diseases of plants -- Florida   ( lcsh )
Leaf spots -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 2).
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065830
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70214311

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9 -// BACTERIAL LEAF SPOT AND BLIGHT OF CALATHEAS

A. R. Chase1 :

University of Florida, IFAS)
Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-93-11 i -sity of Fiord

Bacterial leaf spot of Calatheas can be caused by either Pseudomonas cichorii which is
fluorescent in culture or another Pseudomonas sp. which is nonfluorescent. Symptoms of
Pseudomonas leaf spot (P. cichorii) are characterized by water-soaked spots that turn dark green
to black. They may have a yellow edge but this is not common. Calathea roseo-picta and C.
'Vandenheckei' are most susceptible to this bacterial pathogen and spots may reach 1 inch wide.
There are rarely more than two spots on a leaf and loss of the leaf often occurs if it is infected
before complete expansion (2).

Symptoms of the Pseudomonas blight (Pseudomonas sp.) are somewhat different. This
bacterial disease has become a problem for calathea growers during the past two years (1).
Symptoms start as water-soaked areas along the leaf veins and are especially visible on new leaves
as they open up. The spots appear clear and run together readily. When completely mature, the
spots are tan to brown and papery. C. roseo-lineata is very susceptible to this pathogen, with
severe symptoms developing even when drip irrigation is used to keep leaves as dry as possible.


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Fig 1. Pseudomonas leaf spot on Fig 2. Pseudomonas blight on
Calathea argentea 'Vandenheckei' Calathea roseo-lineata caused
caused by P. cichorii. by Pseudomonas sp.

Professor of Plant Pathology, University of Florida, IFAS, Central Florida Research
and Education Center Apopka, 2807 Binion Rd., Apopka, FL 32703.









Control of Pseudomonas leaf spot should be based on eliminating overhead watering as
much as possible to reduce conditions for infection and spread of the bacterium between plants.
Preventive applications of a copper bactericide may aid in disease control but none are labeled
for calathea at this time. Control of Pseudomonas blight is more difficult. Infected plants should
be destroyed since the bacterium is systemic in infected plants. Although tissue culture plants
may be free of the disease when purchased they are as easily infected as cuttings. Other controls
mentioned for P. cichorii can be used as well.

Since Pseudomonas blight is so difficult to control even when the best cultural conditions
prevail the following studies were undertaken to determine resistance of some Calatheas and
related plants to this bacterial pathogen. The table lists the plants tested for susceptibility to
Pseudomonas blight. Many calatheas and all marantas tested were immune to the pathogen while
Stromanthe 'Burle Marx' was as susceptible as C. omata.

References

1. Leahy, Robert. 1991. Bacterial leaf spot of Calathea spp. P1. Path. Circ. No. 345, Fl. Div.
of P1. Industry. (not in print)
2. Wick, R. L. and Robin Shrier. 1990. Pseudomonas leaf spot of Calathea picturata
'Argentea'. Phytopathology 80:124.


Table 1.


Susceptibility of Calatheas and their relatives to Pseudomonas blight.


Plant Symptoms Susceptibility level"
Calathea concinna marginal/interveinal burning low to medium
Calathea leperdina marginal burning slight
Calathea majestica interveinal burning low to medium
Calathea makoyana none immune
Calathea orata interveinal burning very high
Calathea roseo-picta marginal burning low to medium
Calathea vittata none immune
Calathea wilson-princep scattered spots high
Ctenanthe lubersii none immune
Maranta leuconeura 'Green' none immune
Maranta leuconeura 'Red' none immune
Maranta leuconeura 'Blue' none immune
Stromanthe amabilis marginal and tip burning very high
'Burle Marx'

"Susceptibility was rated from lowest to highest: immune, slight, low, medium, high and very high.




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