Group Title: ARC-A research report - Agricultural Research Center-Apopka ; RH-75-1
Title: Caladium disease control
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 Material Information
Title: Caladium disease control
Series Title: Apopka ARC research report
Physical Description: 5 leaves : ; 28 cm.
Language: English
Creator: Knauss, James Frederick, 1938-
Magie, R. O ( Robert Ogden ), 1906-
Publisher: University of Florida, IFAS, Agricultural Research Center
Place of Publication: Apopka Fla
Publication Date: 1975
Subject: Caladium -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: J.F. Knaus and R.O. Magie.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065950
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70922021

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

J. F. Knauss and R. O. Magie'

University of Florida, IFAS ..

Apopka ARC Research Report RH7T5


A. Bacterial U 1976

Erwinia carotovora A S

Erninia chrysan-themi F"l-o Oridaj

B. Fungal

Sclerotium rolfsii

Botpryts app.

Fusarium solani, Fusarium spp.

S Pythium nyriotylum, Pythium spp.

Phytophthora spp.?

Rhizoctonia spp.

Rhipu spp.?


For planting stock, always select the healthiest tubers harvested from the

previous year's crop. The pathogens mentioned above survive from one season

to the next on infected tubers and selection of the best tubers (those which

appear the healthiest) for planting stock will keep the initial pathogen

population introduced into the planting area low. This is important because

low pathogen numbers early in caladium field culture usually aids in reducing

disease development throughout the growing season. Heat treatment of the

Associate Professor, ARC-Apopka and Professor, AREC-Bradenton, respectively.
2The authors thank Dr. Frank Marousky, AREC-Bradenton, for his suggestions
regarding the proper curing conditions for caladium bulbs.


planting stock at 1220F for 30 min, prior to cutting into planting chips is essential

in caladium culture and may be the difference between success or failure of the crop.

In research experiments, Benlate 50 WP (1.5 lb/100 gal) and streptomycin (200 ppm) have

been added to the heated treatment water with no adverse effect on their activity.

Both might be tried on a limited basis to a portion of the planting stock to further

evaluate their effectiveness when used in this manner. Proper heat treatment of planting

stock will eliminate Pythium and Phytophthora and possibly a portion of the other fungal

pathogens prior to chipping, dusting and subsequent planting. Heat-treated tubers are

much less likely to initiate disease through introduction of pathogens into the planting

area or in the planting chips. In tuber heat treatment, it is essential that the

temperature is maintained as close to 122F as possible and not be allowed to exceed

is temperature during the 30 min. treatment period. Constant observation of the

thermometers during the heat treatment process is important and worth every minute spent.

After the 30 min. heat treatment, extract the tubers and cool immediately ip clean

tap water**. After cooling, allow the tubers to dry in a clean area before cutting

into chips. Do not place these heat-treated tubers where they may become recontaminated

with caladium pathogens before chipping and planting. If you are heat treating for the

first time, do not be alarmed if after planting, the pieces seem a little slow in

germinating. Heat treatment has been shown to delay germination for approximately

7-10 days with no adverse effect upon later growth and bulb production. After heat

treatment and cutting the tubers, immediately apply a fungicide--bactericide dust.

Dusts which have been successfully employed on chips are:

Captan (5-10%)

Difolatan (5-10%)

SCaptan (5%) + Benlate (2.5%)

Captan (50) + Benlate (2.5%) + Streptomycin (0.5%)

Add streptomycin (200 ppm/100 gal water) to cooling water.

All these dusts are given in percentage of active ingredient.

In fall, after digging, wash tubers thoroughly and spray with or dip in a solution

containing 3 lb of Captan plus 200 ppm streptomycin/100 gal of water. Benlate 50 WP

might also be included in the spray or dip at l4 lb/100 gal. Ten percent Botran or

Difolatan dusts have also been reported as satisfactory in controlling storage rots

of tubers.

After digging, washing and chemically treating, tubers should be dried thoroughly

with fans. For curing, tubers are held at 80-900F for 10 days to 2 weeks. These

temperatures are helpful in developing a coating of suberin over the wounded areas.

Suberin is the chalky-white scar tissue which forms over injured surfaces. The suberin

layer protects against excessive drying and against' disease development. After tubers

cured, they should be stored at a controlled temperature of 700F. In the event

controlled temperature storage is not available, tubers may be stored at ambient

temperatures but the temperature should not be allowed to go below 700F for prolonged

periods. Caladiums are cold sensitive and are injured when exposed to low temperatures

(40-60F). Injury can vary from slight inhibition of growth to death. Death by cold

injury (40F for 6 days) can easily be mistaken for rotting by a disease organism.


A. Bacterial

Xanthomonas spp.

Erwinia spp.?

B. Fungal

Pythium yriotylum, Pythium spp.

S Phytophthora spp.

Sclerotium rolfsii

Rhizoctonia spp.

Fusarium solani, Fusarium spp.


Prepare the planting area properly for fumigation. Grade the soil in a manner that

allows the boundary areas to slope away from the area to be planted. Make certain the

drainage ditches are large enough to handle all anticipated run-off from the field.

These practices will help prevent wash-ins into the treated area and help to prevent its

recontamination. Fumigate the planting area, including road and turn areas. Plant

dusted chips obtained only from healthy heat-treated tubers. The following information

on field application of fungicides is to be taken as preliminary and is based upon

research conducted since 1972 and on results obtained from research conducted on

ornamental foliage plants. This research is continuing so that within the coming years

specific recommendations can be made based on thorough research results. At present,

it is felt that in-row spray treatments in the planting furrow at planting time, coupled

Pth 2 or more band treatments at the base of the plants during the growing season may

provide assistance in keeping the root and crown decay pathogens of caladiums under

control. The following fungicides and their stated concentrations on a 100 gal water

basis have given safe and effective control of the caladium pathogens listed:

Pythium spp.

Truban 30 WP (12 oz)

Sclerotium rolfsii

Terraclor 75 WP (1 ib)

Fermate 76 WP (2 Ib)

Demosan 65 WP (1 Ib)

Rhizoctonia spp.

Benlate 50 WP (12-16 oz)

S Terraclor 75 WP (1 ib)

Fermate 76 WP (2 Ib)

In the tropical foliage industry, Truban has been combined with either Benlate,

Fernate or Terraclor to produce a wide-spectrum soil fungicide. Benlate should never

be used alone as an in-row or band spray treatment and should always be used in

combination with Truban. The normal rate of application for these soil fungicides is

1 pint/sq ft or 1 pint/each 3 feet of a 4 inch band or in-row treatment. To cut down

on the amount of fungicide suspension needed, it is safe to increase the fungicide

concentration by puttingthe same amount in 25 gal water and applying pint/sq ft or

4 pint per each 3 feet of 4 inch band or in-row treatment. Although even higher

fungicide concentrations and corresponding lower application rates might be used, they

are not suggested because research has not yet determined their safety to caladiums.

Follow the chemical band applications with to 1 inch of irrigation water. One

optionn to applying the fungicides at a 4X concentration and following the chemical

band application with to 1 inch of irrigation water would be when either Sclerotium

rolfsii or Rhizoctonia are visibly attacking the basal portion of the leaves at the

soil line. In this case, the normal concentration of the fungicide stated on Page 4

should be used and the band application should only be followed with a light watering

to wash the chemicals from the upper foliage. Whenever possible, all the proceeding

chemical band applications should be done in the cooler morning hours, with the later

afternoon and evening hours as a second choice.




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