Group Title: ARC-A research report - Agricultural Research and Education Center - RH-82-10
Title: Chemical control of Myrothecium crown rot and leaf spot of Rex begonia
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00066478/00001
 Material Information
Title: Chemical control of Myrothecium crown rot and leaf spot of Rex begonia
Series Title: ARC-A research report
Physical Description: 3 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1982
Subject: Begonia rex -- Diseases and pests -- Control -- Florida   ( lcsh )
Myrothecium -- Control -- Florida   ( lcsh )
Leaf spots -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 3).
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066478
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 - 71211710

Table of Contents
        Page 1
        Page 2
        Page 3
Full Text


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

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida



A. R. Chase
University of Florida, IFAS .
Agricultural Research Center ApopkJ i
ARC-A Research Report RH-82-10

Myrothecium crown rot and leaf spot is a serious disease ofTmany.--. 'j

ornamental plants including gloxinia (2), aphelandra (1), dieffenbachia,

begonia, aglaonema, and lipstick vine. Symptoms are usually found on

leaves and appear as dark brown to black somewhat circular lesions which

can be wet or dry. The lower side of lesions contain black fruiting

bodies of the pathogen surrounded by a white fringe. They are easily

visible to the naked eye and are diagnostic for this disease. Leaf

spots of gloxinia and begonia may occur but the most serious symptom is

the crown rot which stops plant growth (begonia) or girdles the stem

when plants near maturity (gloxinia). The purpose of this research

was to identify the optimum chemical control for Myrothecium crown rot

and leaf spot of begonia.

Begonias were obtained from tissue culture and planted in 4" pots

in a medium containing Canadian peat, cypress shavings, and pine bark

(2:1:1 by volume) which was amended with 4.4 kg Osmocote (19:6:12), 4.2

kg dolomite, and 0.9 kg Micromax (micronutrient source) per m3 of medium.

After one week the plants became naturally infected with Myrothecium

roridum and benomyl (2.3 g/gal) was applied as a drench to all pots.

No control was achieved and the same plants were then employed in the

following experiment.

All plants were artificially inoculated with spores of M. roridum.

After one week chemical sprays (Table 1) were initiated and continued

on a weekly interval for a total of eight applications. Fungicides

were applied at the recommended rates to foliage and plant crowns with

the exception of CGA 64250 which was used as a soil drench applied at

the rate of 40 ml per pot twice at monthly intervals. Fifteen plants

were used in each treatment. Plants were evaluated for quality by

counting the number of healthy leaves after five applications and the

percentage of high quality plants at the end of the experiment.

All of the fungicides were safe for use on Rex Begonia except the

CGA 64250. This chemical caused leaf deformity, severe stunting and

burning. In another test, a similar reaction was noted when gloxinias

were drenched with this compound. The best plants were produced when

either Daconil or Manzate were used. The number of healthy leaves and

percentage of high quality plants at the end of the test support the

superiority of these compounds compared to the others used (Table 1).

Past research involving the control of this disease on gloxinia (3)

indicated that Rovral at 3.8 g/gal was effective and safe. Since their

tests did not include either Daconil or Manzate a comparison cannot be

made. Use of Daconil or Manzate at the recommended rates on a weekly

interval provided good, safe control of Myrothecium crown rot and leaf

spot of Rex Begonia in this test.

Use of trade names in this report implies no endorsement of specific

pesticides but were used only as a means of identification.

Table 1. Influence of chemical treatments on control of Myrothecium
crown rot and leaf spot of Rex Begonia.

Mean no. healthy
Treatment Rate leaves/plant Percentage high quality
4/15/82 5/11/82
Benlate 50WP 2.3 g/gal 3.7 ay 27
Manzate 75WP 6.8 g/gal 5.6 b 53
Ornalin 50WP 2.3 g/gal 3.5 a 7
Rovral 50WP 2.3 g/gal 3.6 a 27
CGA 64250 1.0 ml/gal 5.5 b 33
Daconil 75WP 6.8 g/gal 6.3 b 67
Zyban 75WP 6.8 g/gal 5.1 ab 33
Water --- 3.5 a 7

ZFungicides were applied weekly for eight weeks.

YNumbers followed by the same letter in the same column were not
statistically significant at the 5% level using Duncan's multiple
range test.

1. Chase, A. R. 1981. Comparison of Myrothecium sp. and Corynespora
cassiicola leaf spots on two cultivars of Aphelandra squarrosa Neese.
Proc. Fla. State Hort. Soc. 94:(in press).

2. Littrell, R. H. 1965. A Myrothecium rot of gloxinias. Plant Dis.
Rptr. 49:124-127.

3. Ploetz, R. C. and A. W. Englehard. 1980. Chemical control of
Myrothecium disease of Gloxinia. Proc. Fla. State Hort. Soc. 93:181-183.

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