Bioefficacy of Fungicides and Plant Extracts against

Alternaria solani Causing Early Blight of Tomato

Deepti Sadana, and Nidhi Didwania

Abstract— Early blight disease of tomato caused by Alternaria

solani (Ellis) is an economically vital disease causing threat to tomato cultivation. In the present investigation all the seven fungicides

(mancozeb, captan, thiram, coppersulphate, carbendazim, zineb and copperoxychloride) reduce the disease severity as compared to untreated check. The highest reduction in the disease was achieved by applying mancozeb (1500 ppm) that caused 86.4 percent inhibition of mycelial growth in A1 strain of Alternaria solani. Bioefficacy of fifteen plant extracts (Polyalthia longifolia, Azadirachta indica, Datura stramonium, Ocimum sanctum, Calotropis procera, Crotalaria juncea, Eucalyptus obliqua, Cassia

fistula, Agele marmelos, Croton bonplonadium, Pergularia daemia, Cleome viscose, Phyllanthus amarus, Bauhinia purpurea, Euphorbia hirta) were evaluated under in vitro conditions. Among plant extracts evaluated, fresh aqueous extract of Eucalyptus obliqua (15%) was effective in causing 88 percent inhibition of mycelial growth in A1 strain of A. solani. Followed by Datura stamonium, Azadirachta indica, Calotropis procera and Polyalthia longifolia. Thus the present study revealed that plant extracts have shown significant

inhibition and proved to be cost effective and ecofriendly for the management of A. solani and were comparable with fungicides.

Keywords: Alternaria solani, fungicides, plant extracts, tomato.

I. INTRODUCTION

OMATO (Lycopersicon esculentum) is the vital solanaceous

vegetable crop of global importance grown in an area of

4.8 million hectares (WPTC, 2012). In India tomato occupies

an area of 880 million hectare, with a production of 18227

metric tons and productivity of 20.7 metric tons/ha in the year

2012-2013 (Indian Horticulture database – 2013). Alternaria

solani (Ellis and Martin) is a soil inhabiting air-borne

pathogen responsible for leaf blight, collar and fruit rot of

tomato disseminated by fungal spores [1].The disease affects

on all parts of the plant and causes great reduction in quantity

and quality of fruit yield [2].Primary methods of controlling Alternaria leaf blight include preventing long periods of

wetness on the leaf surface, cultural scouting, sanitation, and

development of the host plant resistance with the application

of fungicides [3]-[4]. Cultivation of resistant varieties is the

ultimate control of this disease. However, farmers in

pursuance of high yield are inclined to cultivate some varieties

which may be less resistant to disease. Also unplanned and

wide use of fungicides often leads to serious environmental

problems besides affecting the health of users and consumers.

So, it is necessary to minimize the use of chemicals for

controlling disease.

Deepti Sadana, Department of Biotechnology, Faculty of Engineering &

Technology, Manav Rachna International University, Faridabad, India

Email: gaganchashaki@yahoo.co.in

The emergence of fungicide resistant strains due to the

application of fungicides for a long period of time has led the

plant pathologists to search for innovative and harmless

fungicides for replacement of recommended chemicals.

Innovative and safe methods and botanicals need to be

identified and evaluated for continuous search to develop

ecofriendly strategies to reduce the dependence on harmful

chemicals. Therefore the present study was aimed to

determine the efficacies of different doses of fungicides and

plant extracts against Alternaria leaf blight of tomato.

II. MATERIAL AND METHODS

Systemic and non-systemic fungicides viz., mancozeb,

captan, thiram, copper sulphate, carbendazim, zineb, copper

oxy chloride were evaluated for their efficacy on mycelial

growth of Alternaria solani at the rate of 500 ppm, 1000 ppm,

1500 ppm concentrations using poison food technique.

The botanicals viz., Polyalthia longifolia, Azadirachta indica,

Datura stramonium, Ocimum sanctum, Calotropis procera,

Crotalaria juncea, Eucalyptus obliqua, Cassia fistula, Agele marmelos, Croton bonplonadium, Pergularia daemia, Cleome

viscosa, Phyllanthus amarus, Bauhinia purpurea, Euphorbia

hirta were evaluated in fresh forms at three different

concentrations viz., 5,10,15 percent by employing food poison

technique.

Isolation of Pathogen and Preparation of Pure Culture

A.solani was isolated from infected tomato leaves by

following single spore isolation methods [5]-[6]. Pure cultures

of different isolates of A. solani was tested for the

pathogencity on tomato leaves, reisolated and maintained on

PDA slants for further investigations.

In Vitro Evaluation of Plant Extracts

Aqueous plant extracts were prepared by grinding 100 g

fresh leaves with 100 ml distilled water (w/v) using a blender

and filtrate was collected using double layered muslin cloth.

All the extracts obtained were passed through Whatman no.1

filter paper and filtrates were finally centrifuged at 10, 000

rpm for 10 minutes. The supernatant was used for assay. A

total of 15 plant extracts / botanicals were evaluated (@ 5, 10,

and 15%) in vitro against A.solani applying food poisoned

technique and using PDA as basal medium. The replication of

treatments was done thrice and untreated suitable control was

maintained.

In vitro Evaluation of Fungicides

Fungicides viz. , mancozeb, captan, thiram, copper sulphate,

carbendazim, zineb, copper oxy chloride at three different

concentrations viz., 500, 1000, 1500 ppm by poison food

technique. The radial growth of the fungal colony was

T

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recorded on 10th day when untreated control plates were

observed to have maximum growth. The percent inhibition

was calculated using the formula of Vincent [7].

I = C - T x 100

C I = percent inhibition of mycelial growth

C = radial growth of fungus in control

T = radial growth of fungus in treatment

III. RESULTS AND DISCUSSION

In vitro Evaluation of Fungicides

The efficacy of seven fungicides against different strains of A. solani at different concentrations is shown in Fig. I. All the

fungicides evaluated caused inhibition of mycelial growth of

pathogen. There was a positive correlation between the

concentration and percent inhibition of growth of mycelium.

Mancozeb was significantly superior over copper sulphate,

copper oxy chloride, and carbendazim in inhibiting mycelial

growth. The maximum percent inhibition was observed in

mancozeb at different concentrations which ranged from 72.40

to 86.40 percent. It was followed by thiram and captan.

Minimum inhibition was observed in carbendazim from 24.1

to 33.7 percent. The results were in conformity with Chethana

et al. [8] and Gondal et al. [9] where mancozeb was found

effective in inhibiting the mycelial growth of A. solani

respectively. Fungicide application can increase the genetic potential and

yield reduction due to disease can be minimized. Preventive

fungicides inhibit the spore germination and penetration but

pathogen can derive resistance against fungicide application so

repeated application of fungicides at proper dose and interval

of time is mandatory [3]-[10].

In vitro Evaluation of Plant Extracts

The plant extract found to be best effective in inhibiting the

growth of pathogen was found to be Eucalyptus obliqua (15%)

and it ranged from 64.9 to 88% as shown in the Tables. This

was followed by Datura stramonium, Calotropis procera,

Polyalthia longifolia and Azadirachta indica. Reduced percent

inhibition was observed in Pergularia daemia followed by

Cleome viscosa and Phyllanthus amarus. The results were in

conformity with Naik et al. [5].

Fig. 1 In vitro evaluation of fungicides at different concentrations against Alternaria solani

TABLE I

IN VITRO EFFECT OF DIFFERENT PLANT EXTRACTS AT DIFFERENT CONCENTRATIONS ON RADIAL GROWTH AND ITS INHIBITION IN A1 STRAIN.

Plant extracts Colony Diameter (mm) Mean(mm) Percent Inhibition Mean %

5% 10% 15% 5% 10% 15%

Polyalthia longifolia 57.0 45.7 20.0 40.9 34.4 47.5 76.7 52.8

Azadirachta indica 56.0 43.0 22.6 40.5 35.6 50.5 73.7 53.2

Datura stramonium 47.6 35.6 15.0 32.7 45.2 59.0 82.5 62.2

Ocimum sanctum 63.6 54.3 30.7 49.5 26.8 37.5 64.3 42.8

Calotropis procera 53.0 44.0 18.0 38.3 39.0 49.4 79.0 55.8

Crotalaria juncea 59.0 48.7 27.0 44.9 43.6 44.0 68.6 52.0

Eucalyptus obliqua 37.3 26.6 10.3 24.7 57.1 69.4 88 71.5

Cassia fistula 60.6 56.3 48.6 55.1 30.3 35.2 43.4 36.3

Agele marmelos 67.4 59.7 40.6 55.9 22.5 31.4 52.7 35.5

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Croton bonplonadium 59.3 49.3 35.7 48.1 31.8 43.3 58.4 44.5

Pergularia daemia 63.6 56.4 30.6 50.2 26.8 35.1 64.4 42.1

Cleome viscose 74.7 67.6 49.6 63.9 14.1 22.2 42.3 26.2

Phyllanthus amarus 74.6 68.0 59.0 67.2 14.2 21.8 31.3 22.4

Bauhinia purpurea 73.6 58.0 46.0 59.2 15.4 33.3 46.5 31.7

Euphorbia hirta 69.3 58.6 47.0 58.3 20.3 32.6 45.3 32.7

Control 87.0 87.0 86.0 86.6 0 0 0 0

SE± (m) 0.10 0.08 0.12 0.12 0.10 0.11

SE± (d) 0.14 0.12 0.18 0.17 0.14 0.15

CD at 1% 0.29 0.25 0.37 0.34 0.28 0.32

Average of three replications Figures in parenthesis are arc sine values.

TABLE II

IN VITRO EFFECT OF DIFFERENT PLANT EXTRACTS AT DIFFERENT CONCENTRATIONS ON RADIAL GROWTH AND ITS INHIBITION IN A2 STRAIN.

Plant extracts Colony Diameter (mm) Mean(mm) Percent Inhibition Mean %

5% 10% 15% 5% 10% 15%

Polyalthia longifolia 50.6 41.0 27.6 39.7 42.0 52.3 67.7 54.0

Azadirachta indica 56.3 46.7 37.0 46.7 35.5 45.7 56.8 46.0

Datura stramonium 34.6 22.6 7.0 21.4 60.3 73.7 91.8 75.3

Ocimum sanctum 61.7 57.6 47.0 55.4 29.1 32.9 44.7 35.6

Calotropis procera 52.0 39.0 31.7 40.9 40.1 54.7 62.7 52.5

Crotalaria juncea 68.0 37.3 25.0 43.4 33.6 56.6 70.8 53.7

Eucalyptus obliqua 40.0 28.6 12.6 27.1 53.8 66.7 85.2 68.6

Cassia fistula 59.3 47.7 35.0 47.3 32.1 44.5 58.7 45.1

Agele marmelos 66.6 44.6 38.0 49.7 23.6 48.1 54.9 42.2

Croton bonplonadium 75.6 58.0 39.0 57.5 13.3 32.6 54.1 33.3

Pergularia daemia 64.7 50.0 34.0 49.6 25.6 41.9 60.3 42.6

Cleome viscosa 71.3 66.3 55.0 64.2 18.3 22.9 35.4 25.5

phyllanthus amarus 73.3 63.0 43.0 59.8 16.0 26.8 49.4 30.7

Bauhinia purpurea 68.3 54.4 40.0 54.2 21.8 36.8 52.6 37.1

Euphorbia hirta 46.0 35.0 22.0 34.3 47.3 59.3 74.3 60.3

Control 87.0 86.0 85.0 86.6 0 0 0 0

SE± (m) 0.082 0.079 0.077 0.10 0.09 0.09

SE± (d) 0.117 0.112 0.109 0.15 0.13 0.12

CD at 1% 0.239 0.229 0.224 0.30 0.27 0.25

Average of three replications

Figures in parenthesis are arc sine values.

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TABLE III

IN VITRO EFFECT OF DIFFERENT PLANT EXTRACTS AT DIFFERENT CONCENTRATIONS ON RADIAL GROWTH AND ITS INHIBITION IN A3 STRAIN.

Plant extracts Colony Diameter (mm) Mean(mm) Percent Inhibition Mean %

5% 10% 15% 5% 10% 15%

Polyalthia longifolia 61.6 42.0 30.0 44.5 28.5 51.7 66.6 48.9

Azadirachta indica 66.0 34.0 24.6 41.5 23.5 60.5 73.6 52.5

Datura stramonium 56.7 35.3 26.3 39.4 34.1 59.4 70.3 54.6

Ocimum sanctum 76.4 49.5 35.0 53.6 11.2 43.0 62.1 38.8

Calotropis procera 52.3 33.0 23.0 36.1 39.4 61.7 74.0 58.4

Crotalaria juncea 71.0 54.6 37.6 54.4 16.6 27.5 45.3 29.8

Eucalyptus obliqua 46.2 28.0 17.3 30.5 46.3 67.8 80.7 64.9

Cassia fistula 68.4 48.6 31.0 49.3 20.5 44.1 65.0 43.2

Agele marmelos 65.0 55.6 46.3 55.6 24.7 36.0 48.7 36.5

Croton bonplonadium 72.0 63.0 49.0 61.3 16.6 27.5 45.3 29.8

Pergularia daemia 75.6 56.2 41.0 57.6 12.4 35.4 54.3 34.0

Cleome viscosa 74.0 65.7 58.0 65.9 14.3 24.5 35.0 24.6

phyllanthus amarus 66.0 43.0 36.0 48.3 23.5 50.6 60.2 44.8

Bauhinia purpurea 77.6 68.0 57.3 67.6 10.0 21.8 36.1 22.6

Euphorbia hirta 62.6 38.3 32.0 44.3 27.4 55.9 66.2 49.8

Control 86.0 87.0 89.0 87.3 0 0 0 0

SE± (m) 0.069 0.077 0.075 0.08 0.09 0.08

SE± (d) 0.097 0.109 0.107 0.11 0.12 0.11

CD at 1% 0.199 0.222 0.218 0.23 0.25 0.22

Average of three replications

Figures in parenthesis are arc sine values.

TABLE IV

IN VITRO EFFECT OF DIFFERENT PLANT EXTRACTS AT DIFFERENT CONCENTRATIONS ON RADIAL GROWTH AND ITS INHIBITION IN A4 STRAIN.

Plant extracts Colony Diameter (mm) Mean(mm) Percent Inhibition Mean %

5% 10% 15% 5% 10% 15%

Polyalthia longifolia 43.0 34.3 24.0 33.8 49.6 60.4 71.4 60.5

Azadirachta indica 31.6 22.3 13.6 22.5 62.9 74.2 83.7 73.6

Datura stramonium 35.0 27.4 18.3 26.9 59.0 68.5 78.2 68.6

Ocimum sanctum 62.0 56.0 46.2 54.7 27.3 36.5 44.8 36.2

Calotropis procera 53.3 46.2 33.5 44.3 37.5 46.3 61.0 48.3

Crotalaria juncea 46.0 36.3 25.3 35.9 46.1 58.5 69.8 58.1

Eucalyptus obliqua 39.0 29.6 20.0 29.5 54.3 66.5 76.2 65.7

Cassia fistula 70.3 62.6 52.3 61.7 17.6 26.5 37.7 27.3

Agele marmelos 66.0 56.3 45.3 55.9 22.3 34.2 46.0 34.2

Croton bonplonadium 65.0 58.0 34.6 52.5 23.8 33.1 58.7 38.5

Pergularia daemia 72.0 67.0 41.6 60.2 15.6 24.2 50.4 30.1

Cleome viscosa 67.0 54.6 42.0 54.5 21.5 38.4 50.0 36.6

phyllanthus amarus 65.0 46.0 36.6 49.2 23.8 47.7 56.3 42.6

Bauhinia purpurea 76.0 64.0 57.2 65.7 11.0 26.1 33.5 23.5

Euphorbia hirta 72.6 50.0 39.3 54.0 14.8 41.9 53.2 36.6

Control 85.0 87.0 86.0 86.6 0 0 0 0

SE± (m) 0.076 0.088 0.069 0.10 0.11 0.09

SE± (d) 0.108 0.124 0.098 0.14 0.16 0.12

CD at 1% 0.221 0.254 0.20 0.28 0.33 0.25

Average of three replications

Figures in parenthesis are arc sine values.

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TABLE V

IN VITRO EFFECT OF DIFFERENT PLANT EXTRACTS AT DIFFERENT CONCENTRATIONS ON RADIAL GROWTH AND ITS INHIBITION IN A5 STRAIN.

Plant extracts Colony Diameter (mm) Mean(mm) Percent Inhibition Mean %

5% 10% 15% 5% 10% 15%

Polyalthia longifolia 48.3 25.0 29.0 34.1 44.7 61.3 66.6 57.5

Azadirachta indica 40.3 29.0 18.0 29.1 53.8 66.7 79.3 66.6

Datura stramonium 45.6 34.3 25.3 35.1 47.7 60.5 70.8 60.0

Ocimum sanctum 61.6 53.6 36.0 50.4 29.4 38.3 58.6 42.1

Calotropis procera 36.2 25.0 12.6 24.6 58.4 71.3 85.4 71.7

Crotalaria juncea 58.0 44.0 28.3 43.4 33.6 49.4 67.4 50.1

Eucalyptus obliqua 37.0 25.0 20.0 27.3 57.6 71.3 77.0 68.6

Cassia fistula 66.7 53.3 46.6 55.5 23.3 38.7 46.3 36.1

Agele marmelos 52.6 38.0 24.3 38.3 39.7 56.3 72.0 56.0

Croton bonplonadium 73.6 49.3 34.6 52.5 15.7 43.3 57.8 38.9

Pergularia daemia 56.5 46.0 34.7 45.7 35.1 47.1 59.7 47.3

Cleome viscose 73.6 53.3 35.6 54.2 25.9 38.7 59.0 41.2

Phyllanthus amarus 66.0 57.3 44.3 55.9 24.4 34.1 49.0 35.8

Bauhinia purpurea 72.2 58.6 34.0 54.9 17.0 32.6 60.9 36.8

Euphorbia hirta 72.0 63.7 53.0 62.9 17.5 26.8 39.0 27.8

Control 87.0 87.0 86.0 86.6 0 0 0 0

SE± (m) 0.076 0.087 0.074 0.09 0.09 0.10

SE± (d) 0.108 0.122 0.104 0.12 0.13 0.14

CD at 1% 0.221 0.251 0.213 0.25 0.26 0.28

Average of three replications

Figures in parenthesis are arc sine values.

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