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Group Title: AREC-A research report - Agricultural Research and Education Center - RH-1984-23
Title: Some new soil fungicides for control of Pythium root rot of foliage plants
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Permanent Link: http://ufdc.ufl.edu/UF00066538/00001
 Material Information
Title: Some new soil fungicides for control of Pythium root rot of foliage plants
Series Title: AREC-A research report
Physical Description: 6 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Agricultural Research and Education Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1984
 Subjects
Subject: Foliage plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Soil fungicides -- Testing -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
Funding: AREC-Apopka research report ;
 Record Information
Bibliographic ID: UF00066538
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 - 71313704

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Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
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Some New Soil Fungicides for Control of Pythium
Root Rot of Foliage Plants
SA. R. Chase
University of Florida, IFAS
Agricultural Research and Education Center---Ap.p |
::AREC-A Research ReportjRHl 8 U- [ -

Root diseases caused by species of Pythlium and yt ohhNoa can be the
most serious problems encountered during foliage plant production. lhile
disease avoidance through use of pathogen-fr e potsa'rs~i otting media,
growing plants on raised benches and starting _itj p hogen-free cuttings or
seedlings is always recommended, many growers find these cultural controls
difficult to implement.- Fungicides applied to the potting.medium before or
after planting are therefore important tools in disease control. Some of the
fungicides currently used to control the pythiaceous fungi listed above are
metalaxyl (Subdue), etridiazole (=ethazol, Truban and Terrazole), propamocarb
(Previcur and Banol) and, fenaminosulf (Lesan). Other fungicides which are
currently under investigation for use in the foliage plant industry include
fosetyl aluminum (Aliette 80WP), benalaxyl (similar to metalaxyl) and two
numbered compounds from Zoecon Chemical Co. (SAN 371F and SAN 518F). The -
following report summarizes tests conducted during the past twelve months at
the AREC-Apopka for control of Pythium splendens on several foliage plants.
METHODS

The pathogen used in all tests was Pythium splendens which was
introduced to the potting medium 1 to 3 weeks after transplanting rooted
cuttings or seedlings. The fungicide treatments were applied twice at
10-week intervals; with plant growth ratings made periodically during the
trials. Soil drench treatments were applied at about 1 pint/ft of surface
area and foliar applications were applied to runoff with a 2-gallon hand
sprayer. Aglaonema commutatum 'Silver Queen', Epipremnum aureum (pothos),
Brassaia actinophylla (schefflera), and Peperomia obtusifolia (peperomia)
were each tested separately with specific treatments given in the tables.
Ten or twelve plants per treatment were arranged in a randomized complete
block design. Plants were grown in various sizes of black plastic pots in a
potting medium composed of Canadian peat, pine bark and cypress shavings in a
ratio of 2:1:1 by volume. The medium was steam-treated for 1.5 hr at 190 F
before adding 1 lb Micromax, 7 lb dolomite and 10 lb Osmocote 19:6:12 per
cubic yard. Tests were performed in a glasshouse receiving about 1800 ft-c
natural light and temperatures ranging from 60 to 95 F.
RESULTS

Aliette and Aglaonema. Treatment did not significantly affect either
height or number of shoots in this trial with Aglaonema. At the end of the

1Associate Professor of Plant Pathology, Agricultural Research and Education
Center, 2807 Binion Road, Apopka, FL 32703.








test both the top and root weights of all plants were determined (Table 1).
In this case best top weight was found on plants treated with the highest
rate of the Aliette drench. The control treatments had the smallest tops as
did those plants treated with either Aliette at the low rate of foliar spray
or the Previcur drench. Root weight is sometimes a better indication of the
degree of root disease control. In this case, the Subdue drench provided by
far the best root mass; the high rate of the Aliette spray or drench also
provided an increase in root growth compared to the controls.

Aliette and Schefflera. In the trial with Schefflera, the height and
numbers of leaves (data not given) were not affected by treatment (Table 2).
The top weight was highest for plants receiving the high rate of the Aliette
drench, with the best root grade found on plants receiving the Subdue drench
which was similar to the previous test.

Aliette and Pothos. As in the previous two tests, ratings of leaves and
height (vine length) were not affected by treatment. Best top weight was
found on plants treated with either rate of the Aliette drench which also
corresponded to best root weight (Table 3). Since no other fungicides were
included in this trial it can only be concluded that the drench application
was superior to the foliar application of Aliette in this trial.

Zoecon compounds and Pothos. Vine length or number of leaves of Pothos
were unaffected by treatments. Best top weight of plants was achieved in the
Subdue drench treatment with good results also achieved for all rates of the
SAN 518 drench treatments. Largest root weights occurred on plants drenched
with the two higher rates of the SAN 371 product (Table 4).

Benalaxyl and Pothos. Number of shoots and top weights were unaffected
by treatment in this trial. Root weights were greatest for plants treated
with benalaxyl at the 3 oz rate or Subdue which were also noninoculated. In
this case all treatments gave good disease control compared to the inoculated
controls (Table 5).

Benalaxyl and Peperomia. Number of shoots was unaffected by treatment
of Peperomias, although the inoculated control had at least one less shoot
compared to any other treatment. Similarly, the number of leaves and the
root grade showed that all noninoculated plants and all inoculated plants
treated with fungicides had higher ratings compared with the inoculated
control plants (Table 6). Top weight of Peperomias was best in the
inoculated treatments receiving benalaxyl at either 1.5 or 6.0 oz/100
gallons. Benalaxyl appeared to provide better disease control in this test
than the Subdue when comparisons were made between inoculated and noninocu-
lated plants receiving the same fungicide drench (Table 6).
CONCLUSIONS

Although these tests were conducted using a limited variety of plants,
several general conclusions can be made regarding the potential use of these
"new" products for Pythium root rot control. These tests indicate that use
of Aliette as a foliar to spray to control root rot varies with type of
plant. In most tests the 5.0 lb rate of Aliette applied as a foliar spray
provided a positive growth response for one part of the plant but not the
other. Overall the 5.0 lb rate of Aliette used as a soil drench appears to









be superior to the foliar application. Subdue treatment usually resulted in
better roots than any Aliette treatment.

The Zoecon products were tested in only one trial on pothos which limits
the application of these results to a wide number of foliage plants. How-
ever, in this trial the SAN 371 drench gave the best roots with the Subdue
giving the greatest growth response of the plant tops.

Benalaxyl is an analog of metalaxyl, the active ingredient in Subdue.
Trials with peperomia and pothos show that the compound provides similar
levels of disease control as well as the growth response for noninoculated
plants. Benalaxyl did cause significant color breaking (mottling) when used
at either the 3.0 or the 6.0 oz/100 gallons rate on pothos while Subdue used
at 3.5 oz (higher than legally labeled use) was safe during this trial.
Overall the benalaxyl treatments appeared to.give better disease control than
the Subdue treatment.

Many soil fungicides provide a marked increase in size of plant tops
even when applied to plants which are not infected with root-rotting
pathogens. This effect may be due to reduced stress by controlling disease
or stimulation of the host directly.


Table 1. Effect of Aliette treatment on growth of Aglaonema commutatum
infected with Pythium splendens.
Final Number Top Root
Treatment.. Rate/100 gal ht (in) shoots wt (g) wt (g)

Noninoculated control --- 18.6az 4.8a 213.6a 131.5a
Inoculated control --- 17.9a 4.9a 202.7a 124.6a
Aliette-foliar 2.5 lb 18.1a 4.7a 208.6a 127.7a
Aliette-foliar 5.0 lb 18.6a 4.7a 229.lab 141.3ab
Aliette-drench 2.0 lb 18.1a 5.1a 229.6ab 135.4a
Aliette-drench 5.0 lb 18.4a 5.1a 260.4b 142.0ab
Subdue-drench 3.5 oz 18.2a 4.9a 229.2ab 157.7b
Truban-drench 8.0 oz 18.6a 5.7a 228.5ab 133.2a
Previcur N-drench 40.0 oz 18.3a 4.9a 201.3a 122.2a
Captan-drench 2.0 lb -17.8a 4.8a 219.4ab 130.1a

ZMeans in the same column were separated using Duncan's new multiple range
test at the 5% level.








Table 2. Effect of Aliette treatment on growth of Brassaia actinophylla
(schefflera) infected with Pythium splendens.

Final Top Root
Treatment Rate/100 gal ht (in) wt (g) gradey

Noninoculated control --- 13.9az 125.4ab 1.0a
Inoculated control --- 14.3a 109.8a 2.3bc
Aliette-foliar 2.5 lb 14.6a 127.6ab 1.8bc
Aliette-foliar 5.0 lb 13.5a 110.4a 2.5c
Aliette-drench 2.0 lb 15.8a 157.6bc 2.3bc
Aliette-drench 5.0 lb 15.7a 172.9c 1.8bc
Subdue-drench 3.5 oz 14.6a 128.9ab 1.7b


ZMeans in the same column were separated using
test at the 5% level.


Duncan's new multiple range


YRoots were graded on the following scale: 1 = good roots throughout the
potting medium, 2 = slight root loss with roots in 50% of the pot, 3 = loss
of 50% of the roots with good roots in only 50% of the pot, 4 = good roots
in less than 25% of the pot, and 5 = no living roots.


Table 3. Effect of Aliette treatments on growth of Epipremnum aureum
(pothos) infected with Pythium splendens.
Length of No.yellow or Top Root
Treatment Rate/100 gal vine (in) dead leaves wt (g) wt (g)

Noninoculated control --- 50.7az 6.8a 128.2ab 37.8cd
Inoculated control --- 49.Oa 8.8a 115.3a 25.8a
Aliette-foliar 2.5 lb 52.2a 6.1a 128.9ab 32.1b
Aliette-foliar 5.0 lb 52.9a 6.5a 127.7ab 34.7bc
Aliette-drench 2.0 lb 55.1a 6.9a 138.6b 41.2d
Aliette-drench 5.0 lb 57.1a 6.3a 134.8b 42.8d

ZMeans in the same column separated using Duncan's new multiple range test at
the 5% level.









Table 4. Effect of Zoecon numbered compounds
(pothos) infected with Pythium splendens.


on growth of Epipremnum aureum


Number Vine Top Root
Treatment Rate/100 gal leaves length (in) wt (g) wt (g)

Noninoculated control --- 13.7az 56.3a 83.6ab 32.2bc
Inoculated control --- 13.5a 56.4a 85.5ab 29.Oa
SAN 371-drench 1.0 oz 13.5a 52.9a 81.7a 30.2a
SAN 371-drench 2.0 oz 13.9a 52.8a 82.6a 38.2d
SAN 371-drench 4.0 oz 15.Oa 61.4a 95.7ab 33.Oc
SAN 518-foliar 1.0 oz 15.0a 60.la 91.6ab 30.9ab
SAN 518-foliar 2.0 oz 15.Oa 58.8a 91.6ab 30.2a
SAN 518-foliar 4.0 oz 13.8a 56.6a 85.6ab 32.2bc
Subdue-drench 3.5 oz 15.2a 61.5a ..98.1b 30.5ab


Means in the same column were separated using Duncan's new multiple range
test at the 5% level.



Table 5. Effect of benalaxyl on growth of Epipremnum aureum (pothos)
infected with Pythium splendens.

Number Top Root
Treatment Rate/100 gal shoots wt (g) wt (g)

Noninoculated control --- 5.7az 248.1a 63.4bc
Inoculated control --- 4.9a 221.8a 36.9a
Noninoculated benalaxyly 1.5 oz 5.6a 235.2a -73.5bc
Inoculated benalaxyl 1.5 oz 5.2a 230.2a 73.0bc
Noninoculated benalaxyl 3.0 oz 5.3a 225.8a 78.2c
Inoculated benalaxyl 3.0 oz 5.0a 218.5a 60.3b
Noninoculated benalaxyl 6.0 oz 5.3a 225.7a 69.6bc
Inoculated benalaxyl 6.0 oz 5.5a 222.4a 60.9b
Noninoculated Subdue 3.5 oz 5.3a 233.3a 78.4c
Inoculated Subdue 3.5 oz 6.0a 233.4a 63.0bc


ZMeans in the same column separated
the 5% level.


using Duncan's new multiple range test at


YAll treatments applied as drenches to the potting medium.








Table 6. Effect of benalaxyl on growth of
with Pythium splendens.


Peperomia obtusifolia infected


Number Number Top Root
Treatment Rate/100 gal leaves shoots wt (g) grade

Noninoculated control -- 52.8bz 11.6a 198.8b 4.2b
Inoculated control -- 40.9a 9.4a 175.6a 2.4a
Noninoculated benalaxyly 1.5 oz 51.0b 11.8a 212.3bc 4.1b
Inoculated benalaxyl 1.5 oz 49.5b 11.3a 222.2c 4.6b
Noninoculated benalaxyl 3.0 oz 53.2b 12.1a 213.8bc 4.3b
Inoculated benalaxyl 3.0 oz 50.9b 11.2a 209.8bc 4.4b
Noninoculated benalaxyl 6.0 oz 48.5b 10.9a 210.4bc 4.2b
Inoculated benalaxyl 6.0 oz 51.3b 10.9a 222.4c 4.5b
Noninoculated Subdue 3.5 oz 50.6b 12.0a .213.9bc 4.4b
Inoculated Subdue 3.5 oz 48.3b 11.6a 197.8b 4.4b


ZMeans in the same column were
test at the 5% level.


separated using Duncan's new multiple range


YAll treatments were applied as drenches to the potting medium.

XRoots were graded on the following scale: 1 = good roots throughout the
potting medium, 2 = slight root loss with roots in 50% of the pot, 3 = loss
of 50% of the roots with good roots in only 50% of the pot, 4 = good roots
in less than 25% of the pot, and 5 = no living roots.




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