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Group Title: Research report - Agricultural Research and Education Center - RH-1982-25
Title: Orthene 75S and its influence on two leaf spots of foliage plants
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Permanent Link: http://ufdc.ufl.edu/UF00066501/00001
 Material Information
Title: Orthene 75S and its influence on two leaf spots of foliage plants
Series Title: Research report
Physical Description: 4 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Osborne, L. S
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1982
 Subjects
Subject: Foliage plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Leaf spots -- Control -- Florida   ( lcsh )
Plants -- Effect of pesticides on -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: A.R. Chase and L.S. Osborne.
General Note: Caption title.
Funding: ARC-A research report ;
 Record Information
Bibliographic ID: UF00066501
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 - 71225942

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HISTORIC NOTE


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
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida







ORTHENE 75S AND ITS INFLUENCE ON TWO LEAF SPOTS OF F
7 -) A. R. Chase and L. S. Osborne
0) '- IFAS, University of Florida
Agricultural Research Center-Apopka


OLIAGE PLANTS

L ; .


Kesearcn Keport, Kn-IL-4 ." 9 8

The influence of pesticides on pests is not always well ,k nbown. _Indirect.

effects such as the influence of a pesticide on a plant (phytotoxicity)

are known in many cases but the effects of insecticides on diseases and

fungicides on insects are not generally documented. The following report

summarizes several experiments on the influence of acephate (Orthene-75S)

on two nontarget organisms (fungi) which cause leaf spot diseases of two

foliage plants. The combinations of pathogen-host used were Fusarium

moniliforme-Dracaena marginata (Fusarium leaf spot) and Bipolaris setariae-

Chrysalidocarpus lutescens (Helminthosporium or Bipolaris leaf spot).

Pathogen-free dracaenas and palms were grown in potting medium consist-

ing of Canadian peat, cypress shavings, and pine bark (2:1:1 by volume)

amended with 7.5 lb. Osmocote(19:6:12), 7 Ib. dolomite and 1.5 lb.

MicromaxR-per cubic yard. Plants were potted in 6" black plastic pots and

grown on a greenhouse bench receiving about 1200 ft-c. and temperatures from

68 90F. The following treatments were used: 1. inoculated, no spray;

2. noninoculated, no spray; 3. inoculated, sprayed 24 hrs before; and 4.

inoculated, sprayed 48 hrs after. The recommended rate of Orthene was

used (0.33 lb/100 gal) for treatments 3 and 4. Ten plants were used for

each treatment. Inoculation consisted of spraying 1x104 conidia onto palms

or pouring 1x106 conidia into the dracaena whorl. Plants were sealed in

plastic bags for 48 hrs after inoculation to insure high humidities and

thus a good infection rate. After 14 days, disease severity was rated from

1 (no disease) to 5 (severe disease). The test was performed three times

for each plant genus.

The influence of Orthene on growth of B. setariae and F. moniliforme






was tested also by growing these fungi on media amended with Orthene at

1/2, 1, 2 and 4x rates (x = recommended rate). The diameter of the fungal

colony was measured after 5-10 days and compared to growth on medium without

Orthene. In addition, the effect of Orthene on germination of B. setariae

conidia was tested using the same rates. Germ tube length and number of

conidia germinating after 4-8 hrs were recorded.
Orthene had a variable effect on severity of Fusarium leaf spot and

Bipolaris leaf spot (Tables 1 and 2). In the first test with Fusarium leaf

spot, Orthene sprays significantly increased the severity of disease compared

to the inoculated control. However, in the other two tests, Orthene did not

significantly influence severity of disease. Results for Bipolaris leaf

spot tests were equally unpredictable (Table 2). Orthene sprays again

increased severity of leaf spot in the first test but results were inconclu-

sive or not significant for the other two tests.
Incorporation of Orthene into culture medium significantly reduced

growth of B. setariae (Table 3) but did not influence the growth of the F.

moniliforme at the rates used (Table 4). Growth of B. setariae was reduced

as much as 66% compared to the control in all four tests. The germination

rate of B. setariae conidia was not affected but the length of germ tubes

was reduced 50% at the 4x rate.

These studies indicate that applications of Orthene can influence severity

of both diseases. Since greenhouse results were so variable, no clear conclu-

sion can be made. Although the laboratory results were consistent, using these
tests to determine actual effects on the host are not satisfactory since they

were not the same as greenhouse tests. Effects of common insecticides and

miticides on disease severity should be considered since they are potentially
important in disease control. This type of research is vital to the successful
development and adaptation of an integrated approach to pest management in the
plant industry.






Table 1. Effect of Orthene on severity

marginata.


of Fusarium leaf spot of Dracaena


Mean severity rating for 10 plantsa
Treatment/Inoculum Test 1 Test 2 Test 3

1. Water/conidia 2.3 bb 2.4 b 2.6 b

2. Water/water 1.1 a 1.0 a 1.0 a

3. Orthene at x rate 2.7 c 2.0 ab 3.1 b
24 hrs before conidia

4. Orthene at x rate 3.1 d 3.1 b 2.8 b
48 hrs after conidia

aDisease was rated on the following scale: 1 = no disease; 2 = 1-10 lesions;
3 = 11-25 lesions; 4 = 26-75 lesions; and 5 = bud death.
bNumbers in the same column followed by the same letter were not statistically
significant at the 5% level using Duncan's New Multiple Range Test.
C0.33 lb/100 gal.




Table 2. Effect of Orthene on Bipolaris leaf spot of Chrysalidocarpus
lutescens.


Treatment/Inoculum


Mean severity rating for 12 plants
Test 1 Test 2 Test 3


1. Water/conidia 2.2 bb 2.8 bc 2.8 b

2. Water/water 1.2 a 1.0 a 1.5 a

3. Orthene at x ratec 3.1 c 2.2 b 2.8 b
24 hrs before conidia

4. Orthene at x rate 2.7 bc 3.1 c 2.6 b
48 hrs after conidia

aSeverity was rated on the following scale: 1 = no lesions; 2 = 1-10 lesions;
3 = 11-25 lesions; 4 = 26-75 lesions; 5 = 76 or more lesions.
bNumbers in the same column followed by the same letter were not statistically
significant at the 5% level using Duncan's New Multiple Range Test.
c0.33 lb/100 gal.









Table 3. Effect of Orthene on growth of Bipolaris setariae.


Concentration
of Orthene
(rate)

0

1/2x

lxc

2x

4x


Test 1

75.0

60.3

37.8

44.0

28.5


Mean colony diameter (mm)a
Test 2 Test 3

84.0 69.8

84.0 58.4

84.0 45.8

69.2 38;2.

35.8 18.2


aMean colony diameter of 5 replicates after 5 days
days (test 1) or 10 days (test 2).
Not tested.

CRecommended rate of Orthene (0,33 lb/100 gal).


Test 4

81.2

ntb

68.2

56.6

47.2


(tests 3 and 4), 7


Table 4. Effect of Orthene on growth of Fusarium moniliforme.


Concentration
of Orthene
(rate)
0

1/2x

lxc

2x

4x


Mean colony
Test 1
71.2

68.0

65.8

65.2

60.8


diameter (mm)a
Test 2
54.2

54.8

53.4

53.8

49.8


aMean colony diameter of five replicates after 5 days (tests 3 and 4),
7 days (test 1) or 10 days (test 2).
Not tested.

CRecommended rate of Orthene (0.33 lb/100 gal).


Test 3
70.6

ntb

68.6

69.8

63.8




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