Group Title: CFREC-Apopka research report
Title: Chemicals for control of Pythium root rot, 1988
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 Material Information
Title: Chemicals for control of Pythium root rot, 1988
Series Title: CFREC-Apopka research report
Physical Description: 2 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1988
Subject: Root rots -- Control -- Florida   ( lcsh )
Plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065319
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70118258

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Chemicals for control of Pythium root rot-1988

Central Science A. R. Chase
Library vIFAS, University of Florida
Library Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-88-13
Pythium root rot is a very common disease affecting the majority of
UniveAi B1i4ts produced. Chemical control is often excellent, in part due
to the wide variety of fungicides that are effective against species of
Pythium. The most common species found on foliage plants in Florida is
Pythium splendens. Fungicide trials were conducted in 1988 to evaluate
various fungicides for control of Pythium root rot on schefflera and
Brassaia actinophylla (schefflera) seedlings from commercial producers
were planted in steam-treated potting medium consisting of Canadian peat
and pine bark (1:1 by volume). The medium was amended with Osmocote (10
Ibs/yd ), dolomite (7 Ibs/yd ) and Micromax (1 Ib/yd3) following steaming
at 1900F for 1.5 hr. One seedling each was transplanted into 6-inch pots
when they were about 6-8 inches tall.
Begonia 'Mini Angel Wings' plants were produced from cuttings. When
cuttings were well-rooted and about 6-8 inches tall they were planted
singly into 6-inch pots containing the peat-pine bark medium.
In each test, the plants were treated a single time with the
appropriate fungicide 3 or 4 days prior to inoculation with 10 ml/pot of a
mycelial slurry of Pythium splendens. Each test included an inoculated and
a noninoculated set of control plants. Ten single pot replicates were used
per treatment.
Test 1 employed scheffleras and the following fungicide treatments:
etridiazol (Truban 30WP 0.6 g/l), etridiazol (Terrazole 35WP 0.45,
0.52, and 0.6 g/l), and metalaxyl (Subdue 2E (0.16 ml/1). Plants were
drenched with a test material on 29 April 1988 and again on 27 May 1988
except Subdue was applied once on 29 April. On 10 June, plant quality (1 =
dead to 5 = excellent), level height, number of leaflets bigger than 1 inch
long and fresh weight of tops were determined. Control of Pythium root rot
was excellent with Terrazole 35WP at 0.45 and 0.52 g/l and Subdue 2E (Table
1). Truban 30WP and Terrazole 35WP were less effective and appeared to
cause some stunting and loss in plant quality.
Test 2 employed begonias and the following treatments: metalaxyl and
benomyl (Subdue 42WP 1.2 and 2.4 g/l), fosetyl aluminum (Aliette 80WP -
1.4 and 2.9 g/l), a combination of fosetyl aluminum and iprodione (Aliette
80WP 1.4 g/l and Chipco 26019 50WP 2.4 g/l) and metalaxyl (Subdue 2E -
0.2 g/l). Plants were drenched or sprayed once on 17 June 1988. On 13
July both level height and fresh weight of tops were determined. Level
height was not affected by treatment but differences in fresh weight of
tops were significant (Table 2). All fungicide treatments provided

1Associate Professor of Plant Pathology. Thanks to the following chemical
companies for partial support of these studies: Ciba Geigy Corp., Rhone
Poulenc, Inc., and UniRoyal Chemical Co.

Although the foliar spray of the higher rate of Aliette 80WP was not as
effective as the other fungicides tested.
This study substantiates the efficacy of several chemical treatments
)r the control of Pythium root rot caused by P. splendens. Application of
different fungicides on an alternate schedule is recommended since the
.kelihood of the development of resistance to the chemicals by the fungus
; thereby decreased. Chemicals should be tested for phytotoxicity prior
5 their being applied on a new crop.

ible 1. Efficacy of Terrazole 35WP, Truban 30WP and Subdue 2E for
controlling Pythium root rot of Brassaia actinophylla (schefflera)
caused by Pythium splendens.

Plant Level Number of Top fresh
'eatment g/litera quality height (in) leaflets weight (g)

inoculatedd 4.4 cd 12.7 d 36.0 b 114.0 d
loculated 2.4 a 6.6 a 22.3 a 30.5 a
*uban 30WP 0.6 2.6 ab 7.4 ab 23.5 a 34.8 a
*rrazole 35WP 0.6 2.9 b 7.8 b 22.5 a 38.6 a
.rrazole 35WP 0.52 4.6 c 11.4 c 34.4 b 104.0 cd
*rrazole 35WP 0.45 4.4 c 11.2 c 32.8 b 92.6 bc
Lbdue 2E 0.16 ml 4.1 c 10.9 c 33.3 b 79.0 b

'esticides were applied on 29 April and 27 May 1988, except for Subdue 2E
which was applied only on 29 April.
'lant quality was rated from 1 (dead) to 5 (excellent).
number of leaflets longer than 1 inch.
unmbers in the same column followed by the same letter were not
significantly different at the 5% level (DNMRT).

ble 2. Efficacy of Subdue 42WP, Subdue 2E, Aliette 80WP and Aliette 80WP
in combination with Chipco 26019 50WP for control of Pythium root rot
of Begonia 'Mini Angel Wings' caused by Pythium splendens.

Level Top fresh
eatment g/liter Applications' height (in) weight (g)

ninoculated 17.5 ab 169.9 b
oculated 17.4 a 117.2 a
bdue 42WP 1.2 drench 18.4 a 180.5 b
bdue 42WP 2.4 drench 18.2 a 178.6 b
iette 80WP 1.4 spray 18.4 a 168.7 b
iette 80WP 2.9 spray 16.6 a 150.5 ab
iette 80WP and 1.4 spray 16.5 a 162.7 b
Chinco 26019 0OwP 2-4

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