Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-93-16
Title: Pseudomonas leaf spot of Ruscus
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Permanent Link: http://ufdc.ufl.edu/UF00065887/00001
 Material Information
Title: Pseudomonas leaf spot of Ruscus
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: Foliage plants -- Diseases and pests -- Florida   ( lcsh )
Leaf spots -- Florida   ( lcsh )
Pseudomonas infections -- 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: UF00065887
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70627268

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( 3-i


PSEUDOMONAS LEAF SPOT OF RUSCUS


A. R. Chase1


SZP 30 '1


University of Florida, IFAS .
Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-93-16


Ruscus hypophyllum (Israeli/Holland ruscus) is a relatively new cut foliage crop which
is becoming popular with retail florits. The stems are durable and may last up to 6 weeks
even after storage at 40C for one month. The single greatest problem faced by Florida
ruscus growers is a bacterial leaf spot caused by Pseudomonas andropogonis. The disease
has caused severe losses since 1989 and continues to spread throughout most nurseries when
ruscus is in production (1). Like many bacterial leaf diseases, Pseudomonas leaf spot of
ruscus is most severe when plants are exposed to overhead irrigation or rainfall and grown
in a crowded condition which keeps plants wet for long periods of time. Trimming out
stems with spots has been shown to be an effective means of reducing disease severity even
when plants were purposely infected. Although clear-cutting infected pots would seem an
ideal way to remove the source of inoculum and control disease, the damage to the ruscus
is too severe and, indeed, disease severity is higher on clearcut plants than on those with
only symptomatic stems removed.

Chemical control of this disease was reported in 1992 for a variety of copper
compounds (2). This work showed that the copper compounds could not control disease
during the summer months when severity was the highest. Additionally, no differences were
noted between the copper compounds tested.


Fig 1. Leaf spot on Ruscus hypophyllum caused by Pseudomonas andropogonis.


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







Two tests were performed between the late July 1992 and October 1993 to evaluate
Kocide 101 77WP, Aliette and vinegar for disease control. Data included the average
number of stems with spots per plant and the average number of spots per plant. Plants
received 8 to 10 weekly treatments before evaluation. They were inoculated after the
second bactericide spray.

There were no significant differences in Test 1 for either the number of spots per
plant or the number of spotted stems per plant (Table 1). The vinegar treatment showed
promise. In Test 2, differences between treatments were statistically significant. Kocide was
the only treatment that significantly reduced the number of spots per plant.

Control of Pseudomonas leaf spot on ruscus is difficult. It is advisable to grow plants
in covered structures to reduce spread of bacteria by rainfall. Growing plants in containers
will allow them to dry more rapidly since they aren't as likely to form a dense mass of stems
and leaves as when grown in ground beds. In addition, they can be spaced out periodically
to increase air circulation between pots. Do not use overhead irrigation since it can spread
bacteria and increase disease severity. Remove spotted stems whenever they are found.
Treatment with bactericides is apparently helpful in some cases.


Table 1. Control of Pseudomonas leaf spot of ruscus with Kocide, Aliette or vinegar.
Test 1 Test 2
9 Jul to 15 Sep 92 29 Jul to 5 Oct 93
Treatment Rate per # stems # spots # stems # spots
100 gal w/spots w/spots
Noninoculated --- 1.1 ay 1.1 a 1.1 a 6.2 a
Inoculated --- 1.2 a 6.0 a 2.2 ab 38.6 b
Kocide 101 1 lb 1.3 a 6.0 a 1.9 ab 7.1 a
77WP
Aliette 80WP 2.5 lb 2.1 a 8.9 a 1.2 ab 13.1 ab
Vinegar 2 gal 0.9 a 1.7 a 2.3 b 27.9 ab

z Data are given as the average number of stems with spots per plant and the average
number of spots per plant.
Y Numbers in the same column followed by the same letter were not significantly
different using Duncan's New Multiple Range Test, P = 0.05.


Literature Cited

1. Chase, A. R. and R. H. Stamps. 1990. Bacterial disease damages ruscus. Cut
Foliage Grower 5(5/6):4.

2. Chase, A. R. and R. H. Stamps. 1992. Copper compounds do not provide adequate
Pseudomonas control on Ruscus. Cut Foliage Grower 7(5/6):1-3.




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