• TABLE OF CONTENTS
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 Front Cover
 Table of Contents
 Introduction
 Symptoms
 The pathogen Cylindrocladium...
 Host range
 Epidemiology
 Chemical control
 Tissue-cultured plantlets
 Summary
 Reference
 Back Cover














Group Title: Bulletin - Agricultural Experiment Station, University of Florida, 860
Title: Cylindrocladium root and petiole rot of spathiphyllum spp.
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00086508/00001
 Material Information
Title: Cylindrocladium root and petiole rot of spathiphyllum spp.
Series Title: Bulletin Agricultural Experiment Station, University of Florida
Alternate Title: Petiole rot of spathiphyllum spp
Physical Description: 20 p. : ill. ; 23 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Poole, R. T ( Richard Turk )
Publisher: Agricultural Experiment Station, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1988
 Subjects
Subject: Spathiphyllum -- Diseases and pests   ( lcsh )
Foliage plants   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: A.R. Chase and R.T. Poole.
General Note: Cover title.
General Note: "August 1988."
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00086508
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 19697314
issn - 0096-607X ;

Table of Contents
    Front Cover
        Front Cover
    Table of Contents
        Table of Contents
    Introduction
        Page 1
        Page 2
    Symptoms
        Page 3
        Page 4
    The pathogen Cylindrocladium spathiphylli
        Page 5
        Page 6
    Host range
        Page 7
    Epidemiology
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
    Chemical control
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
    Tissue-cultured plantlets
        Page 20
    Summary
        Page 20
    Reference
        Page 21
    Back Cover
        Page 22
Full Text
1oo

August 1988


Bulletin 860


Cylindrocladium Root and
Petiole Rot of
Spathiphyllum spp.

A. R. Chase and R. T. Poole


Agricultural Experiment Station
Institute of Food and Agricultural Sciences
University of Florida, Gainesville -
J. M. Davidson, Dean for Research .,


''ru. 27 O ?-


Anmversity of Florida






Table of Contents


Page


Introduction

Symptoms

The Pathogen Cylindrocladium spathiphylli

Host Range

Epidemiology

Chemical Control

Tissue-Cultured Plantlets

Summary

References


Acknowledgements
Appreciation is extended to Jeanne M. F. Yuen and William A.
McLees for technical assistance, and to Debbie Kennedy, Elina
Faircloth and Nancy Cochrane for preparation of this manuscript.
Special thanks to N. E. El-Gholl and C. L. Schoulties for the
micrographs used in this bulletin.


Cover. Infection of Spathiphyllum 'Bennett' with C. spathiphylli showing
chlorosis and loss of lower leaves (plant on right). The plant on the left
is healthy.






Cylindrocladium Root and Petiole Rot
of Spathiphyllum spp.
A. R. Chase and R. T. Poole

Dr. Chase is Professor of Plant Pathology and Dr. Poole is Professor of Plant
Physiology at the IFAS Agricultural Research and Education Center, Apopka,
Florida 32703


Introduction
Spathiphyllum species and cultivars make up an important portion
of Florida foliage plants, constituting approximately 10% of the
foliage plants produced in south Florida and 5% of those produced
in central Florida in 1985. In 1975, they accounted for only 3% of
the foliage plants produced in Florida. The increase in popularity of
this plant group occurred at the same time that a severe disease of
Spathiphyllum spp. appeared and spread throughout the industry.
Cylindrocladium root and petiole rot of Spathiphyllum spp. was
described in 1980 by Schoulties and El-Gholl, with the first incidence
of disease reported in late 1979. The pathogen was identified as
Cylindrocladium floridanum Sobers & Seymour, which causes
production losses in several other ornamentals grown in the south-
eastern United States. In 1982, the pathogen was described as a new
species, Cylindrocladium spathiphylli Schoulties, El-Gholl & Alfieri.
Cylindrocladium root and petiole rot of Spathiphyllum appears to
have been absent prior to 1979, although many growers were
producing this plant during the 1960s and 1970s. Spathiphyllum with
symptoms of this disease have been seen growing in tropical Central
and South America, leading to the theory that C. spathiphylli was
introduced into Florida by movement of infected plants from the
tropics. This theory is supported by the rapid spread of the disease
throughout the majority of Spathiphyllum producers in Florida over
a 2-year period. Long-distance dissemination of the disease is easily
accomplished by transfer of infected seedlings, contaminated seeds
and established plants, all of which commonly occurred among
Florida producers prior to the presence of this disease in Florida.
Considerable research has been conducted during the past 9 years
on Cylindrocladium root and petiole rot of Spathiphyllum spp. in an
effort to more fully understand the biology of the pathogen and
epidemiology of this disease. Much of the published research has
centered around use of fungicides for disease control. This technical






























Figure 1. Typical symptoms of naturally infected Spathiphyllum sp.
seedlings with Cylindrocladium root and petiole rot caused by
C. spathiphylli.


Figure 2. Close-up view of a petiole lesion on Spathiphyllum sp. caused by
an artificial inoculation with C. spathiphylli.






bulletin was written to review published and unpublished information
available on the biology of the pathogen, epidemiology of the disease,
and the potential of an integrated approach for disease control.

Symptoms
The earliest symptoms of Cylindrocladium root and petiole rot are
slight wilting and chlorosis of lower leaves. These leaves gradually
turn necrotic, and bases of petioles become rotted, and detach from
the main plant (Figure 1). When high moisture conditions are present,
conidia may splash onto petioles and leaves, forming elongated
dark-brown to black lesions with a bright yellow halo (Figure 2).
Lesions may range from a pinpoint to 1 cm in length.
The root system of plants showing slight loss of lower leaves may
appear unaffected initially, with roots rotting later. Occasionally
petioles bend sharply downward about 1 cm from the surface of the
potting medium (Figure 3). During the winter, petiole epinasty and
a general chlorosis may be the most common symptoms seen. In
advanced stages of disease development the entire top becomes


Figure 3. Spathiphyllum sp. artificially inoculated with C. spathiphylli
showing epinasty of many petioles.







completely separated from roots (Figure 4). Plants in 11.4 liter
containers, with high quality foliage void of symptoms, are frequently
found without roots.
Development of symptoms is associated with the site of the initial
infection. Crowns of plants infected by splashed conidia rot there
first, whereas plants infected through drainage holes in pots develop
severe root rot before showing any foliar symptoms. Conidia of the
pathogen are readily produced on rotted petioles and stem bases,
and the disease can be diagnosed easily through microscopic exami-
nation of this tissue. If only root symptoms are present, isolation
on culture media is recommended to verify the causal agent, since
Pythium root rot appears similar to Cylindrocladium root rot.


Figure 4. Severely infected Spathiphyllums frequently show complete
separation of leaves and petioles from the roots.







Generally, on smaller plants (12.5 cm pots and smaller), the severity
of symptoms of roots and foliage is similar. On large plants, however,
that correlation is usually very low, and roots must be examined to
evaluate plant health.

The Pathogen Cylindrocladium spathiphylli
C. spathiphylli was previously identified as C. floridanum.
Schoulties et al. (1982) elaborated on the differences between the two
species, establishing C. spathiphylli as a new species of Cylindro-
cladium, differing from Spathiphyllum sp. 'Clevelandii.' Their
manuscript fully describes the morphology of the pathogen as well
as its taxonomic relationship to C. floridanum.
Cultures of C spathiphylli are initially white and cottony, becoming
variously brown to reddish-brown after approximately 2 weeks on
either potato-dextrose agar (PDA) medium or V-8 juice agar (V-8A)
medium. Conidiophores branch dichotomously, are hyaline and
smooth, and terminate in two to four phialides that are cylindrical
and occasionally doliform or reniform. Stipes arise from procumbent
mycelia or sclerotia in culture, and terminate in a hyaline, granular,
globose vesicle (9.0 to 15.0 tm in diameter). Conidia form singly at
phialide apices, and are held together in a palisade-like cluster by
a mucilagenous substance. Conidia are also hyaline, straight, rounded
at both ends, and usually one-septate (45.0 to 101.0 tm long by 5.0
to 7.0 lm wide) (Figure 5).
Direct observations of C. spathiphylli conidiophores and conidia
on roots and petioles of infected plants are sometimes sufficient to
make an accurate diagnosis (Figure 6). To ascertain the presence of
the pathogen, roots and petioles of plants are washed in tap water,
and tips with both necrotic and healthy tissue are removed. They
are then stained with lactophenol cotton blue and examined with a
microscope at 100 X magnification. Conidia of C. spathiphylli readily
absorb this stain and are easily seen if present.
C. spathiphylli is easily isolated from diseased roots and petioles
of many species and cultivars of Spathiphyllum. Isolation frequencies
are unaffected by concentrations of up to 2.6% active ingredient (ai)
sodium hypochlorite (NaOC1) used as a surface-disinfestant, and by
exposure times from 1 to 10 minutes. This is possible due to the
pathogen's relative resistance to high concentrations of NaOC1, since
recovery of saprophytic fungi from the same tissue was reduced
approximately 75%. This effect of using a partial vacuum during
surface-disinfestation was not statistically significant.
The effect of continuous temperatures on radial growth of
C. spathiphylli was tested on V-8A at temperatures between 15 C




























Figure 5. Two-celled conidia of C. spathiphylli stained with aniline blue-
lactophenol (magnification 500 X).


Figure 6. Clusters of conidia from an infected Spathiphyllum are sometimes
visible and can be sufficient for an accurate diagnosis.






and 33 C (Table 1). These temperatures were tested because
Spathiphyllum production commonly occurs within this range. Five
plates per temperature were inoculated with a 7-mm inoculum disk,
wrapped in aluminum foil and a polyethylene bag, and placed in an
incubator. Radial growth was measured after 7 to 11 days incubation.
Growth occurred over this temperature range, reaching a maximum
between 210C and 30 C (Table 1).

Host Range
Considerable research has been reported on the host range
C. spathiphylli on some Spathiphyllum species and cultivars and
other foliage plants in the family Araceae. Only Spathiphyllum
species and cultivars have been found to be susceptible (Schoulties
and El-Gholl, 1983). Additional research evaluated eight different
cultivars or species of Spathiphyllum for susceptibility to
C. spathiphylli.
Plants were established in a steam-treated (1.5 hours at 90 C)
potting medium (50% Canadian peat:50% pine bark) amended with
4.2 kg dolomite, 4.4 kg Osmocote (N:P:K, 19:6:12) and 0.9 kg
Micromax (micronutrient source) per m3. All plants were inoculated
with 10 mL of a mycelial slurry plus conidia created by blending
2-week old culture of C. spathiphylli on V-8A in 200 mL of sterilized
deionized water. Plants were grown in a greenhouse with
temperatures between 15 OC and 30 oC, and maximum light levels of
175 1mol/m2/s. Ratings were made weekly on a scale from 1 (no
disease) to 5 (76% to 100% diseased). Figure 7 shows plants rated
1 through 5.



Table 1. Effect of various continuous temperatures on radial growth of
Cylindrocladium spathiphylli grown on V-8 juice agar medium in the dark.
Temperature Mean radial growth (mm)t
C Test 1 Test 2
15 37.6* 20.6*
18 48.2 22.8
21 60.0 31.0
24 56.6 32.8
27 56.6 34.2
30 51.4 27.6
33 41.0 24.6
t Value given is a mean for 5 replicates measured after 11 days (Test 1) or 7 days
(Test 2) of incubation.
Significant level of P < 0.01.
























Figure 7. Rating system used for all Cylindrocladium root and petiole trials
with an asymptomatic plant on the left. The ratings are from left to right
1, 2, 3, 4, and 5.


After 8 weeks, disease severity depended upon the type of host
species of cultivar infected. Symptoms of disease on all susceptible
cultivars were typical of those previously described on Spathiphyllum
sp. 'Clevelandii.' The cultivars tested (Table 2) appeared to be highly
susceptible, with the exceptions of S. cannifolium, S. floribundum,
and S. floribundum 'Mini' (a dwarf selection). Resistance of S. flori-
bundum was previously reported (Schoulties and El-Gholl, 1983).
Although the various cultivars of species react differently to this
pathogen, all die if symptoms of infection develop.
Experiments with Rumohra adiantiformis (leatherleaf fern) showed
that isolates of C. spathiphylli could cause leaf spots similar to those
caused by C. pteridis and C. heptaseptatum, both of which are found
naturally on this host (Schoulties and El-Gholl, 1983). In contrast,
these latter pathogens did not cause a disease of Spathiphyllum spp.

Epidemiology
Disease Development and Spread
The pathogen is most active when the temperature is warm, the
soil is wet, and the air is humid (Schoulties et al., 1983). This
corresponds with observations of the amount of time between
inoculation and plant death. This period can be from 8 to 12 weeks






during the winter, while during the summer it shortens to 3 or 4
weeks. Most of the spread of inoculum occurs through water
movement, and infections occur when water splashes conidia onto
plant foliage, or washes conidia along the ground or bench and into
drainage holes in pots. Many infections can be traced to a probable
source by examining the area of the plant with the most severe
symptoms. In one experiment, when a central core of plants was
inoculated with conidia of C. spathiphylli, approximately 3 months
elapsed before symptoms were detected in surrounding, noninocu-
lated plants. Infected plants were sometimes adjacent to inoculated
plants and other times far away, with many apparently healthy
plants in between.

Host Nutrition
Altering host nutrition has been used as a means of reducing the
susceptibility of many plants to specific pathogens. Research was
conducted at the AREC-Apopka to evaluate the potential of varying
host nutrition to control Cylindrocladium root and petiole rot. Plants
were established in the medium described in the Host Range Section,
but without the addition of Osmocote. They were then topdressed
with various rates of Osmocote 19:6:12 and allowed to grow in a
greenhouse at temperatures ranging between 15 C and 30 C, and
light levels of 150 to 200 Mmol/m2/s. The recommended rate of
fertilization for Spathiphyllum spp. under these conditions is 2.5 g
per 12.5 cm pot every 3 months. The rates tested were 0, 3, 6, 9, 12,
and 15 g per 12.5 cm pot in the first test, and 0, 1, 2, 3, 4, 5, and
6 g per 12.5 cm pot in the second test. Plants were inoculated 8 weeks

Table 2. Response of Spathiphyllum species and cultivars to artificial
infection with Cylindrocladium spathiphylli.
Mean disease severity rating t
Spathiphyllum species and/or cultivar Test 1 Test 2 Test 3
S. floribundum 1.0 a* 1.0 a 1.1 a
S. floribundum 'Mini' 1.5 a 1.3 a 1.0 a
S. cannifolium 1.3 a 1.1 a 1.6 a
Tasson 2.6 b 4.1 b 3.0 b
Mauna Loa 3.2 bc 5.0 c 4.9 c
Bennett 3.6 bc 4.4 b 4.7 c
Wallisii 4.3 c 4.9 c 4.4 c
Queen Amazonica 4.4 c 4.3 b 2.9 b
t Values given are the mean for 10 plants rated 8 weeks after inoculation according
to the following scale: 1 = no symptoms, 2 = 1 to 25% diseased, 3 = 26 to 50%
diseased, 4 = 51 to 75% diseased, and 5 = 76 to 100% diseased, usually dead.
* Means followed by the same letter within a column were not significantly different
at P s 0.05 (Duncan's new multiple range test).







Table 3. Effect of host nutrition on severity of Cylindrocladium root and
petiole rot of Spathiphyllum sp.
Mean disease severity rating*
Grams 19-6-12 Osmocote per 12.5 cm pott 4-30-82 5-6-82
0 1.3** 1.4**
3 2.1 3.5
6 1.9 2.9
9 2.1 2.6
12 2.1 2.6
15 2.4 2.9
t Fertilizer was applied once on 1-28-82 as a top dressing.
Plants were inoculated on 3-31-82 and rated for disease severity on the dates given
according to the following scale: 1 = no disease, 2 = 1 to 25% diseased, 3 = 26 to
50% diseased, 4 = 51 to 75% diseased, and 5 = 76 to 100% diseased, usually dead.
** F test significant at P < 0.01.



after fertilizer application. They were rated for disease severity 4 and
5 weeks later. Disease severity was significantly less in plants
receiving no fertilizer, but was approximately equal for all plants
receiving different fertilizer levels (Table 3).
The speed with which disease develops during the spring (plants
were inoculated March 31, 1982) is also apparent, as mean disease
severity increased from ratings of 2.1 to 3.5 (inoculated control) in
a single week (Table 3). In the second trial all plants were equally
susceptible to C. spathiphylli, with severity ratings ranging from 4.0
to 5.0. The increase in severity ratings may be due to the time of
year during which the second test was performed (plants were
inoculated August 20, 1982). The increased temperatures may have
resulted in increased disease development.
Soil Temperature
Recent work has been performed to explain the effects of soil
temperature on development of Cylindrocladium root and petiole rot.
Plants were established in various potting media (discussed later)
and inoculated with the pathogen in the manner described previously.
They were placed on benches that allowed some degree of tempera-
ture control from a heating system under the bench.
Benches were maintained with the following temperature ranges:
1) 25 C to 29 C; 2) 21C to 24C; and 3) 19C to 22C. Ten plants
in each of three potting media were placed on each bench and
inoculated on January 1, 1985. Disease severity was significantly
greater on plants on the two warmer benches. On February 6, 1985,
ratings were 2.4, 1.8 and 1.1 for benches 1, 2 and 3, respectively, and
1 week later, 2.9, 2.8 and 2.0. A second trial performed between







February 15, 1985, and March 6, 1985, validated these results.
Although it is unlikely that soil temperatures of 25 C to 29 C can
be avoided during the summer months in Florida, certainly the use
of soil-heating systems in the winter should be avoided on
Spathiphyllum spp. sensitive to C. spathiphylli.

Potting Medium Compaction
The effects of potting medium compaction and components on
disease severity were tested in a variety of trials. A trial on soil
compaction included three compaction levels: 0, 0.14 and 0.3 kg/cm2
pressure. The medium used was a mixture of Canadian peat (75%
by volume) and pine bark (25% by volume) that was steam treated
and amended with 4.4 kg Osmocote (N:P:K, 19:6:12), 4.2 kg dolomite,
and 0.9 kg Micromax per m3. Plants were grown for 8 weeks in a
greenhouse with temperatures ranging from 15C to 30 C, and light
levels between 150 and 200 tmol/m2/s prior to inoculation. Plants were
irrigated three times per week. Plants were inoculated on March 10,
1982, and disease evaluated on June 8, 1982. Disease severity was
3.4, 4.0 and 4.7 for the 0, 0.14 and 0.3 kg/cm2 compaction treatments,
respectively. Greater compaction apparently favored development
of disease, presumably due to decreased root aeration and increased
moisture in the potting medium.
Potting Medium Components
Potting medium composition is another important facet of plant
production. In the test described in the Soil Temperatures Section,
the following media were employed: 1) Canadian peat:sand (50% each
by volume); 2) Canadian peat:pine bark (50% each by volume); and
3) Canadian peat:vermiculite:perlite (50%:25%:25% by volume).
Media were steam-treated prior to the addition of standard rates of
dolomite (4.2 kg/m3), Micromax (0.9 kg/m3), and Osmocote (N:P:K,
19:6:12, 4.4 kg/m3). Plants were irrigated three times per week. Plants
were inoculated 1 month after establishment in these media, and
rated about 3 weeks later for disease severity. In this trial, disease
severity was unaffected by potting medium.
Additional trials were conducted with five potting media created
by mixing a single component with Canadian peat in a 50:50 mixture
(by volume). The components employed were pine bark, perlite,
Styrofoam, Compro (a composted sewage product) and mushroom
compost. Although disease severity ranged from 2.0 to 2.8,
differences in potting media had no significant effects on disease
severity. Other trials using these and other components gave similar
results. Apparently potting medium composition does not






significantly affect disease development.
Potting Medium pH
The effect of potting medium pH was evaluated in a mixture of
Canadian peat and pine bark (50:50 by volume) amended with 0, 2.5,
5.1, 7.6, or 10.2 kg dolomite per cubic meter, Micromax (0.9 kg/m3)
and Osmocote (N:P:K, 19:6:12, 4.4 kg/m3). Single plants were placed
in each of 20 pots per potting medium and grown in a greenhouse
under standard conditions. Plants were inoculated on November 11,
1984 with C. spathiphylli about 3 weeks after potting and
disease was rated weekly starting on December 4, 1984 (about 3
weeks after inoculation). The potting media pH 1 week after potting
ranged from 3.4 to 6.2, and at the end of the trial, the range was 3.8
to 7.1. Ratings indicated that the amount of dolomite affected disease
severity as greatly in the first weeks of the trial as at any other time
(Table 4). Rate of disease development was similar for all treatments,
regardless of the amount of dolomite added (about 1.0 unit increase
over the test period). This indicates that although disease severity
was lower for plants with higher soil pH's, the higher soil pH simply
delayed onset of symptoms and did not permanently arrest disease
development. Similar tests were performed using MgSO,47HO and
CaSO4, since these compounds do not change potting medium pH.
Disease severity was unaffected by the amount of these sulfates
added, indicating that pH and not magnesium or calcium concentra-
tion affected disease severity.


Table 4. Effect of dolomite additions to potting media on severity of
Cylindrocladium root and petiole rot of Spathiphyllum sp.
Kilograms dolo- potting medium Mean disease severity rating*
mite per m3 pH reading
1-1 medium 10-31-84 12-7-84 12-4-84 12-19-84 1-2-85
0 3.4** 3.8** 2.0** 2.5** 3.1**
2.4 4.7 5.0 1.5 2.0 2.6
4.8 5.7 6.3 1.3 1.9 2.5
7.2 6.2 6.8 1.3 1.8 2.3
9.6 6.2 7.1 1.2 1.5 2.2
t Medium was composed of equal volumes of Canadian peat and pine bark, was
amended with 0.9 kg Micromax per m3.
Mean severity rating for 10 plants based on the following scale: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and 5 = 76
to 100% diseased, usually dead.
** F test significant at P < 0.01.







Planting Depth and Irrigation Frequency
Depth of planting and irrigation frequency can influence severity
of stem root diseases. Spathiphyllum sp. were planted in a steam-
treated potting medium (50% Canadian peat, 25% pine bark and
25% cypress shavings by volume) at three different depths: 1 cm
above the junction of roots and leaves (deep); at the junction (normal);
or 1 cm below that junction (shallow). They were also irrigated 1,
3, or 5 times per week. Ten pots were used for each treatment in a
3 X 3 factorial experiment. Plants were inoculated the day after
potting (October 3, 1983) and rated for disease severity on weekly
intervals starting October 21, 1983.
Disease severity was significantly affected by planting depth, but
not by irrigation frequency in the first experiment (Table 5). Shallow-
potted plants were more severely affected than those potted too
deeply or at the normal level. A second trial was performed between
November 14 and December 22, 1983, using the same treatments.
In this test, neither factor significantly affected disease severity,
indicating that disease development is not generally dependent on
either plant depth or irrigation frequency.


Chemical Control
Initial research on chemical control of Cylindrocladium root and
petiole rot was published in 1982. Since that time, much research
has been conducted to evaluate factors to improve the use of


Table 5. Effect of planting depth and irrigation frequency on severity of
Cylindrocladium root and petiole rot of Spathiphyllum sp.
Mean disease severity rating
Treatment Test 1 (10-21-83) Test 2 (12-22-83)
Irrigation/week
1 1.6ns* 2.3ns
3 1.6 2.7
5 1.7 2.5
Potting depth**
deep 2.0 2.4ns
normal 1.6 2.6
shallow 1.4 2.5
t Disease severity given is the mean for 30 plants rated on the following scale:
1 = no disease, 2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75%
diseased, and 5 = 76 to 100% diseased, usually dead.
Significance of the F test denoted as ns = not significant and P < 0.05.
** Plants potted 1 cm above the junction of roots and leaves (deep) at the junction
(normal) and 1 cm below the junction (shallow).







Table 6. Relative efficacy of fungicides for control of Cylindrocladium root
and petiole rot of Spathiphyllum spp.


Fungicide
Triflumizole
Prochloraz
Benomyl
XE-779
Thiophanate methyl
Thiophanate methyl and mancozeb
Iprodione
CGA-64250
CGA-64251
Pentachloronitrobenzene (PCNB)
Captan
Ferbam
Thiram
Vinclozolin
MF-667
MF-654 (benodanil)


chemicals for disease control as well as screen new compounds that
have become available.
All chemical testing trials were performed with plants grown as
described in the Host Range Section. At least one fungicide drench
was applied prior to inoculation. Drenches were applied at the rate
of 0.5 ml per cm2 on a weekly basis. Each trial included noninoculated
and inoculated control treatments, and was usually comprised of ten
single pot replicates per treatment.
Trials concerning the use of a wide variety of fungicides have been
performed throughout the past 4 years. Table 6 summarizes the
relative efficiency of materials tested up to 1988. Overall, benomyl,
prochloraz and triflumizole provided the best control of Cylindro-
cladium root and petiole rot. Iprodione, thiophanate methyl, and
XE779 products also provided some disease control, but were not
as effective as the other three compounds.
Comparisons of benomyl and thiophanate methyl (a closely related
compound) showed that benomyl provided a high level of control at
0.15 g (ai) per liter, whereas thiophanate methyl provided a similar
degree of control only when used at 0.6 g (ai) per liter. Rates of
benomyl from 0.3 to 1.2 g (ai) per liter provided equivalent control
(Table 7), with phytotoxicity noted at rates of 0.9 g (ai) per liter or
above (Figure 8). These rates are excessive, damaging and illegal.
Prochloraz (MF-718) is a compound relatively new to the United
States, and was tested for control of Cylindrocladium root and petiole
rot beginning in 1984. Early tests showed that this compound works
as well as benomyl when used at 0.6 g (ai) per liter (Table 7). Further


Relative degree of control
high
high
high
moderate
moderate
moderate
moderate
moderate
moderate
poor to moderate
poor
poor
poor
poor
poor
poor






testing verified that prochloraz provides a higher degree of disease
control than benomyl. Two other numbered compounds which also
have been tested are triflumizole (Terraguard 50 WP) and dithianon
(MF-711). Triflumizole showed a high degree of disease control, but
dithianon did not provide sufficient control to warrant further
testing.
In 1985 and 1986 several of the newer compounds (including
prochloraz and triflumizole) were evaluated for efficacy. The potential
for a combination treatment of these compounds with benomyl was
evaluated by combining one of the two newer compounds at 0.15 g
(a.i.) per liter with each other or benomyl. In addition, each compound
was tested singly at 0.15 or 0.3 g (a.i.) per liter. Results of this trial
indicated that all rates of prochloraz and triflumizole when used
singly or in combination were more effective in controlling


Figure 8. Phytotoxicity symptoms on Spathiphyllum sp. drenched five times
at weekly intervals with 2.4 g (a.i.) benomyl per liter.






Table 7. Effect of benomyl or prochloraz on efficacy and phytotoxicity on
Spathiphyllum sp. artificially inoculated with Cylindrocladium spathiphylli.
Mean disease Phytotoxicity
Rate (ai) severity rating* % plants with
Treatment per liter 1-18-85 1-31-85 2-13-85 marginal necrosis
Noninoculated 1.2 1.1 1.2 0
Inoculated** 3.2 3.8 3.2 0
Benomyl 0.3 g 1.3 1.5 1.8 0
Benomyl 0.6 g 1.1 1.2 1.2 10
Benomyl 0.9 g 1.0 1.1 1.1 80
Benomyl 1.2 g 1.2 1.2 1.3 70
Prochloraz 0.3 g 1.0 1.4 1.8 0
Prochloraz 0.6 g 1.2 1.4 1.8 0
Prochloraz 0.9 g 1.1 1.2 1.3 0
Prochloraz 1.2 g 1.1 1.1 1.3 0
t Plants were drenched at the rate of 0.5 ml per cm2 weekly for a total of 8 weeks.
* Mean disease severity rating for 10 replicates rated as follows: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and
5 = 76 to 100% diseased, usually dead.
** Plants were inoculated on 12-14-84.
Cylindrocladium root and petiole rot than benomyl (Table 8). There
was no benefit achieved by combining the compounds.
Triflumizole was tested in 1986 for best treatment interval at either
0.3 or 0.6 g (a.i.) per liter. Good disease control was achieved with
applications of 0.3 g applied every other week (Table 9). In the same
year the effect of timing with respect to infection was tested. Plants
were treated with benomyl or triflumizole 10 days before inoculation,
5 days after inoculation or at the onset of symptoms (18 days after
inoculation). Even when applied before inoculation, benomyl at 0.3 g
(a.i.) per liter did iot provide as high a degree of control as triflumizole
applied at 0.075 g (a.i.) per liter 5 days after inoculation (Table 10).
Unfortunately, neither of the compounds could provide adequate
disease control after the onset of symptoms.
The role of soil temperature in degree of control achieved with
prochloraz, benomyl, or triflumizole was tested in 1988. At soil
temperatures of 65 o or 70 F, all three compounds provided excellent
disease control (Table 11). At soil temperatures of 75 or 80 F only
prochloraz and triflumizole provided excellent disease control with
benomyl failing to give comparable control. Use of benomyl for
control of Cylindrocladium root and petiole rot during the summer
months especially may fail due to higher soil temperatures.
Additional research has been conducted using benomyl with
several other agents added to the tank mix. Aquagro was added to
either 0.3 or 0.6 g (ai) benomyl per liter at the rate of 0.08 ml (ai)
per liter. Addition of Aquagro did not affect the degree of disease
control in either test.








Table 8. Efficacy of benomyl, prochloraz and triflumizole used singly and
in combination for control of Cylindrocladium root and petiole rot of
Spathiphyllum sp.
Mean disease severity rating*
Treatment Rate (a.i.) per liter (5-16-85)
Noninoculated 1.2 a t
Inoculated** 4.0 c
Triflumizole 0.15 g 1.9 b
Triflumizole 0.30 g 2.1 b
Triflumizole 0.15 g
and benomyl 0.15 g 1.6 ab
Triflumizole 0.15 g
and prochloraz 0.15 g 1.9 b
Prochloraz 0.15 g 1.6 ab
Prochloraz 0.30 g 1.5 ab
Prochloraz 0.15 g
and benomyl 0.15 g 1.2 a
Benomyl 0.30 g 3.8 c
t Plants were drenched at the rate of 0.5 ml/cm2 weekly for a total of 6 weeks.
* Mean disease severity rating for 10 replicates rated as follows: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and 5 = 76
to 100% diseased, usually dead.
t Numbers in the column followed by the same letter were not significantly different
at P 0.05 (Duncan's new multiple range test).
** Plants were inoculated on 3-27-85.


Table 9. Effect of treatment interval and rate on efficacy of triflumizole for
Cylindrocladium root and petiole rot of Spathiphyllum sp.
Mean disease
Rate (a.i.) No. applications severity rating*
Treatment per liter per 4 weeks (5-13-86)
Noninoculated 4 1.0 a t
Inoculated** 4 5.0 d
Triflumizole 0.3 g 4 2.7 b
Triflumizole 0.3 g 2 3.0 b
Triflumizole 0.3 g 1 4.2 c
Triflumizole 0.6 g 4 2.8 b
Triflumizole 0.6 g 2 4.1 c
Triflumizole 0.6 g 1 4.6 c
Benomyl 0.6 g 4 5.0 d
t Plants were drenched at the rate of 0.5 ml/cm2 weekly for a total of 8 weeks.
* Mean disease severity rating for 10 replicates rated as follows: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and
5 = 76 to 100% diseased, usually dead.
** Plants were inoculated on 3-17-86.
t Numbers in the column followed by the same letter were not significantly different
at P 0.05 (Duncan's new multiple range test).








Table 10. Effect of treatment timing on efficacy of triflumizole or benomyl
on Cylindrocladium root and petiole rot of Spathiphyllum sp.
Mean disease
Rate (a.i.) severity rating*
Treatment per liter First application (5-20-86)
Noninoculated 10 d before 1.0 a t
Inoculated** 10 d before 4.9 f
Benomyl 0.300 g 10 d before 3.3 cd
Benomyl 0.300 g 5 d after 3.6 cd
Benomyl 0.300 g 18 d after 4.9 f
Triflumizole 0.150 g 10 d before 1.2 ab
Triflumizole 0.150 g 5 d after 2.5 bc
Triflumizole 0.150 g 18 d after 4.1 de
Triflumizole 0.075 g 10 d before 2.3 b
Triflumizole 0.075 g 5 d after 2.7 bc
Triflumizole 0.075 g 18 d after 4.5 ef
t Plants were drenched at the rate of 0.5 ml/cm2 weekly for a total of 8 weeks.
* Mean disease severity rating for 10 replicates rated as follows: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and
5 = 76 to 100% diseased, usually dead.
I Numbers in the column followed by the same letter were not significantly different
at P < 0.05 (Duncan's new multiple range test).
** Plants were inoculated on 3-25-86.
The first fungicide application occurred 10 days prior to inoculation, 5 days following
inoculation or 18 days following inoculation (at the onset of symptoms).


Table 11. Effect of soil temperature on efficacy of benomyl, prochloraz or
triflumizole for Cylindrocladium root and petiole rot of Spathiphyllum sp.
Temperature
Rate (a.i.) (Mean disease severity rating* 2/18/88)
Treatment? per liter 65 70 75 80
Inoculated 3.7 4.8 4.9 5.0
Benomyl 0.6 g 1.1 1.0 3.0 3.2
Prochloraz 0.6 g 1.0 1.0 1.0 1.0
Triflumizole 0.6 g 1.0 1.0 1.1 1.1
Significance I
Fungicide (F) **
Temperature (T) **
FXT **
t Plants were drenched at the rate of 0.5 ml/cm2 weekly for a total of 8 weeks.
* Mean disease severity rating for 10 replicates rated as follows: 1 = no disease,
2 = 1 to 25% diseased, 3 = 26 to 50% diseased, 4 = 51 to 75% diseased, and
5 = 76 to 100% diseased, usually dead.
t Significance of the F test (P < 0.01).
** Plants were inoculated on 1-4-88.























Figure 9. Effect of transplanting on root growth of Spathiphyllum sp.
naturally infected with C. spathiphylli. The plant on the right remained
in its original container while the one on the left was transplanted into
steam-treated potting medium prior to four weekly applications of
0.3 g (a.i.) benomyl/per liter.



Similar trials were conducted with a quaternary ammonium
compound (Prevent) used to disinfest greenhouse benches and other
inanimate surfaces. Prevent was moderately effective in controlling
Cylindrocladium root and petiole rot when used alone, and also
increased benomyl's degree of control when it was added to benomyl.
Transplanting large stock Spathiphyllum sp. proved to be
important in the degree of control provided by subsequent benomyl
drenches. Severely infected Spathiphyllum sp. in 20-cm pots were
either left in their original containers and potting medium or
transplanted into new containers with steam-treated potting
medium. All plants were then drenched 4 times with benomyl
(0.3 g (ai) per liter) on a weekly basis. Examination of the root
systems at the end of the experiment (6 weeks total) revealed a
significantly better root system on plants that had been transplanted
compared to those that had not (Figure 9).
Development of a scheme for chemical control of Cylindrocladium
root rot must include preventive measures. Once symptoms have
occurred, it is not likely that a significant degree of control can be
achieved with benomyl or triflumizole. Although triflumizole
(Terraguard 50 WP) is currently available (Section 18) it does not
completely control this disease.






Tissue-Cultured Plantlets
During the past 6 years, the tissue culture industry has supplied
an increasing number of Spathiphyllum propagation materials used
in Florida. Currently, few growers use seedlings of any but the most
unusual Spathiphyllum cultivars. One of the major benefits of using
these tissue-cultured plantlets is that they are generally free from
Cylindrocladium root and petiole rot. Thus, the grower can start with
a healthy plant and use standard cultural means for exclusion of the
disease from the plants.
To maintain a disease-free Spathiphyllum, most growers should
follow these guidelines.
*Do not grow the plants on the ground, especially if the area
contained Spathiphyllums infected with Cylindrocladium in the past.
*Water the plants minimally for the production of a healthy crop.
*Use only new pots.
*Use only new potting medium.
*Apply fungicides for root rot control to the potting medium, not
the foliage.
*Avoid soil heating systems during the winter.
*Avoid soil compaction.
*If you see symptoms of this disease, have a plant pathologist
culture the pathogen, and discard all symptomatic plants.

Summary
Cylindrocladium root and petiole rot has become a limiting factor
in production of Spathiphyllum spp. in the past 10 years. Early
research centered on description of the disease, investigations into
the host range of the pathogen, and chemical control methods. Most
recently, cultural control techniques involving host nutrition, potting
medium composition and pH, soil temperature, and host resistance
have been investigated. Of the many potential elements of a disease
control program for Cylindrocladium root and petiole rot on
Spathiphyllum spp., perhaps the one with the greatest promise is
development of cultivars with increased resistance to the pathogen.
In the future, use of an integrated program employing resistant
cultivars (preferably from tissue culture), soil pH of about 6.5, and
routine applications of the most effective fungicide(s) will allow
continued production of this popular and important foliage plant.






Tissue-Cultured Plantlets
During the past 6 years, the tissue culture industry has supplied
an increasing number of Spathiphyllum propagation materials used
in Florida. Currently, few growers use seedlings of any but the most
unusual Spathiphyllum cultivars. One of the major benefits of using
these tissue-cultured plantlets is that they are generally free from
Cylindrocladium root and petiole rot. Thus, the grower can start with
a healthy plant and use standard cultural means for exclusion of the
disease from the plants.
To maintain a disease-free Spathiphyllum, most growers should
follow these guidelines.
*Do not grow the plants on the ground, especially if the area
contained Spathiphyllums infected with Cylindrocladium in the past.
*Water the plants minimally for the production of a healthy crop.
*Use only new pots.
*Use only new potting medium.
*Apply fungicides for root rot control to the potting medium, not
the foliage.
*Avoid soil heating systems during the winter.
*Avoid soil compaction.
*If you see symptoms of this disease, have a plant pathologist
culture the pathogen, and discard all symptomatic plants.

Summary
Cylindrocladium root and petiole rot has become a limiting factor
in production of Spathiphyllum spp. in the past 10 years. Early
research centered on description of the disease, investigations into
the host range of the pathogen, and chemical control methods. Most
recently, cultural control techniques involving host nutrition, potting
medium composition and pH, soil temperature, and host resistance
have been investigated. Of the many potential elements of a disease
control program for Cylindrocladium root and petiole rot on
Spathiphyllum spp., perhaps the one with the greatest promise is
development of cultivars with increased resistance to the pathogen.
In the future, use of an integrated program employing resistant
cultivars (preferably from tissue culture), soil pH of about 6.5, and
routine applications of the most effective fungicide(s) will allow
continued production of this popular and important foliage plant.






References


1. Chase, A. R. 1982. Control of Cylindrocladium root rot of
Spathiphyllum. Proc. Fla. State Hort. Soc. 95:139-141.
2. Chase, A. R. 1986. Current developments in chemical control of
foliage plant diseases. SAF Proceedings of the Second Conference
on Insect and Disease Management on Ornamentals. pp. 130-137.
3. Chase, A. R., and C. A. Conover. 1986. Effect of soil temperature
on severity of Cylindrocladium root and petiole rot of
Spathiphyllum. AREC-Apopka Research Report, RH-86-7.
4. Chase, A. R., and R. T. Poole. 1985. Root rot Is steam
treatment the answer? Greenhouse Manager 4(2):142, 145-146,
and 149.
5. Chase, A. R., and R. T. Poole. 1987. Effects of potting medium
pH and air temperature on severity of Cylindrocladium root and
petiole rot of Spathiphyllum sp. Plant Disease 71:509-511.
6. Henny, R. J., and A. R. Chase. 1986. Screening Spathiphyllum
species and cultivars for resistance to Cylindrocladium
Spathiphylli. HortScience 21(3):515-516.
7. Schoulties, C. L., A. R. Chase, and N. E. El-Gholl. 1983. Root
and petiole rot of Spathiphyllum caused by Cylindrocladium
spathiphylli. Fla. Dept. Agric. and Cons. Serv., Div. P1. Indus.,
P1. Path. Circ. 218 (revised).
8. Schoulties, C. L., and N. E. El-Gholl. 1980. Pathogenicity of
Cylindrocladium floridanum on Spathiphyllum sp. cv. Cleve-
landii. Proc. Fla. State Hort. Soc. 93:183-186.
9. Schoulties, C. L., and N. E. El-Gholl. 1983. Host range and
pathogen specificity studies of Cylindrocladium spathiphylli.
Proc. Fla. State Hort. Soc. 96:282-284.
10. Schoulties, C. L., N. E. El-Gholl, and S. A. Alfieri, Jr. 1982.
Cylindrocladium spathiphylli sp. nov. Mycotaxon 16(1):265-272.
11. Smith, C. N., and J. R. Strain. 1976. Market outlets and product
mix for Florida foliage plants. Proc. Fla. State Hort. Soc.
89:274-278.



































1 UNIVERSITY OF FLORIDA I


This publication was promulgated at a cost of $3160.10, or 90 cents
per copy, to inform Florida growers about effective treatment for
cylindrocladium infection.



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Agricultural Experiment Station are open to all persons regardless of race,
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