Evaluation of new fungicides and insecticides for phytotoxicity and management of late leaf spot and rust in groundnut

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1 Evaluation of new fungicides and insecticides for phytotoxicity and management of late leaf spot and rust in groundnut M. Reddi Kumar*, M.V. Madhavi Santhoshi, T. Giridhara Krishna and K. Raja Reddy Department of Plant Pathology, Institute of Frontier Technology, Regional Agricultural Research Station, ANGRAU, Tirupati , Chittoor (dt), Andhra Pradesh, India * ABSTRACT Six fungicides and six insecticides were evaluated alone and in combination for phytotoxicity and also their effect on control of leaf spot and rust diseases of groundnut under field conditions during Kharif, Physical compatibility of insecticides and fungicides was recorded under in vitro conditions by taking observations on, solubility, appearance, ph etc. Slight phytotoxicity symptoms were noticed in combinations viz T14: T1+T8 (Imidacloprid +Propiconazole); T26:T3+T8 (Thiodicarb + Propiconazole); T27: T3+T9 (Thiodicarb + Tebuconazole ) followed by T38:T5+T8 ( Novaluron + Propiconazole ) recorded as 24.9, 21.77,19.67,19.66%, respectively when compared to control. When fungicides and insecticides were evaluated against leaf spot and rust diseases in combination and alone, the treatment T40: T5+T10 (Novaluron + Difenoconazole) which recorded lowest percent disease index (PDI) 28% and 17.59%, respectively when compared to individual application. KEY WORDS: Fungicides, groundnut, insecticides, leaf spot, physical compatibility, rust INTRODUCTION Plant protection has assumed greater importance in increasing agricultural production. The real challenge before Agricultural scientists today is to increase production and reduce cost of production to enable Indian products to compete in the International market. With more area under high yielding varieties coupled with higher rate of irrigation and fertilizer application and other management practices, adequate plant protection umbrella has become essential. They use combination of fungicide-fungicide, fungicide-insecticide and fungicide-plant extract, with the hope that some combinations are equally effective against pests with relatively lesser cost of application. Such combinations become inevitable when a farmer is confronted with sudden appearance of disease/ insect/weed in farm which have to be combated without much loss of time. As such the combinations of different plant protection chemicals in integrated pest management is gradually gaining importance. Combined application of pesticides saves time, labour and money by reducing number of sprays and results in delayed emergence of resistance in pests. In some crop/diseases, combinations of full/reduced rate of fungicides can be used economically. Fungicide-fungicide, fungicide insecticide, 246

2 fungicide-herbicide and fungicide-plant extract combinations can be developed to combat various diseases and pests and also reduce the chances of development of resistance in pests. In groundnut, late leaf spot and rust diseases are the most widely distributed and economically important foliar diseases causing severe damage to the crop ( McDonald and Subramanyam,1985). Both diseases together can cause up to 70 per cent yield loss in India. Besides reducing pod yield, these diseases have adverse influence on seed quality. Keeping in view the importance of the problem and lack of information on compatibility of latest plant protection chemicals, investigations were conducted to evaluate the efficacy of newly released insecticides and fungicides for their synergistic/ antagonistic properties and their compatibility under in vitro and field conditions. The effect of insecticides and fungicides alone and in combination were studied in the control of late leaf spot and rust diseases of groundnut. MATERIAL AND METHODS Investigations were conducted during in the Department of Plant Pathology, Institute of Frontier Technology, Regional Agricultural Research Station, Tirupati. The general laboratory techniques followed were those described by Nene and Thapliyal (1979). Six insecticides viz; Imidacloprid, Fipronil, Thiodicarb, Chlorfenapyr, Novaluron, Monocrotophos and six fungicides viz; Hexaconazole, Propiconazole, Tebuconazole, Difenconazole, Chlorothalonil, Carbendazim were used to test physical compatibility viz;, solubility, appearance, ph etc under in vitro conditions and recorded phytotoxicity symptoms produced in combination of fungicides and insecticides under field condition. List of fungicides and insecticides along with trade names used in laboratory and field studies Treatment Name of Insecticide/ fungicide Insecticides T1 Trade name & Company Recommended Dose Imidacloprid TATA MIDA (Rallis) 0.3 ml/l T2 Fipronil Regent (Bayer) 2 ml/l T3 Thiodicarb Larvin (Bayer) 1 g/l T4 Chlorfenapyr Lepido ( PI Industries Ltd) 2 ml/l T5 Novaluron Rin On (Indofil Chemicals 1 ml/l Company) T6 Monocrotophos Monphos 40 (Coromandel 1.6 ml/l International Ltd) 247

3 Fungicides T7 Hexaconazole Contaf (Rallis, TATA Enterprise) 2 ml/l T8 Propiconazole Tilt 25 EC (Syngenta) 1 ml/l T9 Tebuconazole Folicur (Bayer) 1 ml/l T10 Difenconazole Score 25 EC (Syngenta) 1 ml/l T11 Chlorothalonil Ishaan ( TATA Rallis Enterprise) 2 g /L T12 Carbendazim Bavistin (Saraswati Agrochemicals ( India) Pvt Ltd 1 g/l Two field experiments were laid during Kharif, with six insecticides and fungicides alone and in combination to test phytotoxicity among combination of fungicides and insecticides. One experiment was conducted using recommended dose of chemicals as mentioned in the Table. Another experiment was conducted using double dose of insecticides and fungicides as farmers resort to use high dosages for controlling pests and diseases and in order to evaluate phytotoxicity symptoms. Total number of treatments : 50; Replications :2; Plot size: 2.5 X1.8 sq.mt; Design : Factorial RBD. Application of chemicals were administered at 40 DAS. Phytotoxicity symptoms on plants were recorded one week after application of chemicals (Fig. 1 &2). Observations for the specific parameters like chlorosis, necrosis, wilting, vein clearing, hyponasty and epinasty were taken using the scale 0 : 0-00, 1: 1-10, 2: 11-20, 3: 21-30, 4: 31-40, 5: 41-50, 6: 51-60, 7: 61-70, 8: 71-80, 9:: 81-90, 10: For recording the late leaf spot and rust disease incidence, groundnut cultivar Narayani was used for experimental studies conducted during The disease affected plants were brought to the laboratory and recorded the severity of diseases based on standard description followed by Subramanyam et al.1995( Fig.3&4). Disease scoring was done using modified 9- point scale (1-9) both for tikka leaf spot and rust diseases ( Fig 5 &6). PDI = (Sum of individual rating/ Total leaflets observed on plants X Maximum disease rating) X 100. The effect of fungicides and insecticides alone and in combination for Late leaf spot and rust diseases were recorded during harvesting stage. The PDI values were transformed by arc sine transformation statistical analysis of data was performed using SPSS software. RESULTS AND DISCUSSION In the present experiment, six fungicides and six insecticides were evaluated for their physical compatibility both under laboratory and field conditions 248

4 and also their effect was studied in the control of late leaf spot and rust of groundnut. Production of phytotoxicity symptoms due to combined application fungicides and insecticides using recommended dose was studied. Effort was also made to study the development of phytotoxicity symptoms by the increased dose of application, as farmers tend to apply excessive application of chemicals unmindful of its phytotoxicity. Under laboratory conditions, various parameters like, solubility, appearance, ph etc were studied by combining fungicides and insecticides. From the table 1, it is evident that when Hexaconazole was mixed with six insecticides viz; Imidacloprid, Fipronil, Thiodicarb, Chlorfenapyr, Novaluron, Monocrotophos, the dull to curd was observed. The fungicide was readily mixed with all insecticides except Thiodicarb, where it was not readily and formation was observed. High alkaline P H ranges from was recorded in combinations. In the case of Propiconazole, the was dull except with Monocrotophos. where slight Yellow was noticed. The fungicide was readily with all insecticides except Thiodicarb, where sediment was formed. Slight precipitation was observed with Fipronil and Chlorfenapyr. ph was moderate ranges from 7.69 to Which in the case of Tebuconazole, the was dull except with Monocrotophos, where no was developed. The fungicide was readily with all insecticides except Thiodicarb, where it was not readily and sediment was formed. Yellow oil droplets were formed on upper surface of solution when mixed with Monocrotophos. ph reaction was highly alkaline ranges from 8.75 to In the case of Difenconazole, was with all insecticides except with Monocrotophos and Imidacloprid in which the solution was clear and transparent. The fungicide was readily with Imidacloprid, Novaluron and Monocrotophos and no was formed. However, when fungicide was mixed with Fipronil Thiodicarb and Chlorphenapyr, they were not readily and sediment/ was formed. When Chorothalonil was mixed with insecticides, the was milky with all insecticides except Monocrotophos, where it was dull. All insecticides were readily with the fungicide and formation was not observed. ph reaction was highly alkaline ranges from 8.30 to However in the case of Carbendazim, when mixed with insecticides, the was pale and readily except Thiodicarb and Chlorfenapyr, in which slight was observed. ph reaction was high alkaline ranges from 8.40 to From the Table (2) it is evident that the little phytotoxic symptoms were seen in some combination treatments viz; T14: T1+T8 (Imidacloprid +Propiconazole); 249

5 T26:T3+T8(Thiodicarb + Propiconazole ); T27: T3+T9 (Thiodicarb + Tebuconazole ) followed by T38:T5+T8 ( Novaluron + Propiconazole ) which showed phytotoxicity symptoms as 24.9%, 21.77,19.67,19.66 respectively when compared to control. When fungicides and insecticides were applied individually at recommended dose showed no phytotoxicity symptoms. No phytotoxicity symptoms were observed in any of fungicide and insecticide combinations except the above combinations. Similar results were also reported by Kennedy et al. (1995) for control of groundnut disease and insect pests by application of carbendazim (0.05%) + mancozeb (0.2%) + monocrotophos (0.05%) at pre-flowering and post flowering stage. However, when they were applied at double dose as farrmers tend to apply high dose of chemicals, phytotoxicity symptoms were noticed. The symptoms were more pronounced in combinations treatments at double dose, when compared to control. When fungicides and insecticides were evaluated against Late leaf spot and Rust diseases in combination and alone (Table 3), the treatment T 40: T5+T10 (Novaluron + Difenconazole) which recorded lowest percent disease intensity (PDI)of 28% and 17.59% against Late leaf spot and rust diseases respectively when compared to control followed by treatment T19:T2+T7 (Fipronil + Hexaconazole) which recorded 33% and 19.47% respectively. Synergistic effect was evident when these insecticides and fungicides were mixed and there was improved control over individual application of chemicals was noticed. From this study, it is evident that tank mixing of fungicides with insecticides did not reduce the efficacy of the fungicides against Tikka leaf spot and rust diseases. Hence, they are compatible with each other for spray application to control the groundnut diseases. These findings are in conformity with the findings of Vijay Bhaskar et al. (2012) carried field studies on the compatibility of fungicides ( Carbendazim, Difenoconazole and Saaf) and insecticides ( Chlorpyriphos, Dimethoate and Monocrotophos) applied for controlling the Tikka disease pathogens, Cercospora arachidicoli Hori and Phaeoisariopsis personata ( Berk. And Curt.) V.Arx. In which, Difenoconazole + Monocrotophos (0.025% %) treatment showed minimum per cent disease intensity (PDI) of 30.97% and maximum pod (2250 kg/ha) as well as fodder yields (6451 kg/ha). CONCLUSION These investigations provide baseline data for understanding the physical reaction between fungicides and insecticides when mixed and the resultant effect i.e. synergistic/ antagonistic efficacy of combination in managing the pest/ disease incidence. It was observed that no deleterious effect has been resulted when fungicides and insecticides under test were mixed except in few combinations. Hence, it is important that while designing management strategies the combination of fungicide and insecticide should be taken into consideration

6 Table 1: Physical compatibility of insecticides and fungicides under in vitro conditions Fungicide Observations Imidacloprid Fipronil Thiodicarb Chlorfenapyr Novaluron Monocrotophos 1.Hexaconazole Color Dull Dull Cloudy White Light White Solubility Not Appearance No No Precipitate No No No precipitat e observed P H Propiconazole Color Dull Dull Dull Dull Dull Slight yellow Solubility Not Observation No Slight Sediment is Slight No No precipitat e formed P H Tebuconazole Color Dull Dull Dull Dull Dull No Solubility Not Observation No Sediment Sediment No No Yellow oil, slight formed droplets formed oil layer at the top P H Difenconazol e 5.Chlorothaloni l Color Solubility Observation Transparent solution No White in Not Precipitat e, oil layer formatio n White in Not Sediment formed, slight layer oil White in White in Not Precipitate, oil layer formation No Clear and transparent solution Oil layer formed at the top P H Color Milky Milky Milky Milky Milky Dull Solubility Observation No No No No No No precipitat e 251

7 P H Pale in Pale in Pale in 6.Cabendazim Color Pale in Solubility Observation No Pale in No precipitat e Not Slight Not Slight No P H Pale in Slight yellow layer Table 2: Evaluation of insecticides and fungicides for phytotoxicity Tr.No Treatment Normal dose* Double dose* T1 IndividualTreatments : Imidacloprid (16.80) T2 Fipronil ( 13.73) T3 Thiodicarb (13.67) T4 Chlorfenapyr (14.48) T5 Novaluron (12.41) T6 Monocrotophos (12.79) T7 Hexaconazole (13.68) T8 Propiconazole (14.31) T9 Tebuconazole (13.79) T10 Difenconazole (13.43) T11 Chlorothalonil (14.03) T12 Carbendazim (11.19) T13 CombinationTreatments : T1+T7(Imidacloprid +Hexaconazole) 5.88 (13.87) 6.97 (15.29) T14 T1+T8(Imidacloprid + Propiconazole) (24.90) (25.48) T15 T1 +T9(Imida cloprid + Tebuconazole) 8.57 (17.00) 8.69 (17.11) T16 T1 + T10 ( Imidacloprid + Difenconazole) 5.71 (13.80) 5.75 (13.98) T17 T1 + T11 ( Imidacloprid + Chlorothalonil) 8.33 (16.72) 8.65 (17.12) T18 T1 + T12 ( Imidacloprid + carbendazim) 10.0 (18.44) (25.71) T19 T2 + T7 ( Fipronil + Hexaconazole) 9.67 (18.10) 9.89 (9.17) T20 T2 + T8 ( Fipronil + propiconazole) 8.33 (16.72) (20.14) T21 T2 + T9 ( Fipronil + Tebuconazole) 8.82 (17.04) 10.0 (18.72) T22 T2 + T10 ( Fipronil + Difenconazole) 6.45 (14.70) 15.90(23.49) T23 T2 + T11 ( Fipronil + Chlorothalonil ) 7.14 (15.48) 9.30 (17.47) T24 T2 + T12 ( Fipronil + carbendazim) 9.67 (18.05) (20.97) T25 T3 + T7 ( Thiodicarb + Hexaconazole) (19.06) 14.70(22.55) T26 T3 + T8 ( Thiodicarb+ Propiconazole ) (19.67) (19.97) 252

8 T27 T3 + T9 ( Thiodicarb + Tebuconazole) (21.77) (22.26) T28 T3 + T10 ( Thiodicarb + Difenconazole) 6.89 (14.89) (18.63) T29 T3 + T11 ( Thiodicarb + Chlorothalonil ) (19.07) (19.12) T30 T3 + T12 ( Thiodicarb + carbendazim ) 9.37 (17.80) 12.90(20.94) T31 T4 + T7 ( Chlorfenapyr + Hexaconazole ) 6.97 (15.28) 9.09 (17.57) T32 T4 + T8 ( Chlorfenapyr + Propiconazole ) 10.0 (18.53) (18.70) T33 T4 + T9 ( Chlorfenapyr + Tebuconazole ) 9.09 (17.54) 10.0 (18.58) T34 T4 + T10 ( Chlorfenapyr + Difenconazole ) (18.77) (18.68) T35 T4 + T11 ( Chlorfenapyr + Chlorothalonil ) 6.45 (14.64) 9.09 (17.60) T36 T4 + T12( Chlorfenapyr + Carbendazim ) 6.89 (15.02) 7.40 (15.75) T37 T5 + T7 ( Novaluron + Hexaconazole) 6.66 (14.94) 6.25 (14.52) T38 T5 + T8 ( Novaluron + Propiconazole ) (19.66) (20.56) T39 T5 + T9 ( Novaluron + Tebuconazole ) 6.66 (14.89) (18.92) T40 T5 +T10 ( Novaluron + Difenconazole ) 6.45 (14.59) 6.89 (14.89) T41 T5 + T11 ( Novaluron + Chlorothalonil ) 6.89 (15.18) 7.14 (15.50) T42 T5 + T12 ( Novaluron + Carbendazim ) 6.89 (14.84) (18.77) T43 T6 + T7 ( Monocrotophos + Hexaconazole ) 7.40 (15.64) 7.40 (15.71) T44 T6+ T8 ( Monocrotophos + Propiconazole ) 6.89 ( (16.15) T45 T6 + T9 ( Monocrotophos + Tebuconazole ) 9.37 (17.80) 9.37 (17.81) T46 T6 + T10 ( Monocrotophos + Difenconazole ) 8.82 (17.18) 10.34(18.74) T47 T6 + T11 ( Monocrotophos + Chlorothalonil) (18.88) (18.73) T48 T6 + T12 ( Monocrotophos + carbenda zim ) 7.14 (15.55) (19.07) T49 Water spray T50 No spray Average of two replications Figures in parenthesis are angular transformed values According to Dunnetts,* indicates significant difference over control at 5 % level. Source Sum of Squares df Mean Square F-value p-value Fungicides **.000 Concentration **.000 Fungicides * Concentration **.000 Error Total

9 Table 3: Effect of fungicides and insecticides alone and in combination against Late Leaf spot and Rust diseases of Groundnut S.No Treatment Late Leaf spot * PDI Rust* PDI 1 IndividualTreatments : Imidacloprid 66.50± ± Fipronil 66.50± ± Thiodicarb 71.00± ± Chlorfenapyr 66.50± ±4.6 5 Novaluron 69.00± ±9.1 6 Monocrotophos 66.50± ±4.5 7 Hexaconazole 53.00± ±5.0 8 Propiconazole 53.00± ±5.0 9 Tebuconazole 52.00± ± Difenconazole 45.00± ± Chlorothalonil 62.50± ± Carbendazim 69.00± ± CombinationTreatments : T1+T7(Imidacloprid +Hexaconazole) 52.00± ± T1+T8(Imidacloprid + Propiconazole) 53.00± ± T1 +T9(Imida cloprid + Tebuconazole) 45.00± ± T1 + T10 ( Imidacloprid + Difenconazole) 45.00± ± T1 + T11 ( Imidacloprid + Chlorothalonil) 56.50± ± T1 + T12 ( Imidacloprid + carbendazim) 72.50± ± T2 + T7 ( Fipronil + Hexaconazole) 33.00± ± T2 + T8 ( Fipronil + propiconazole) 45.00± ± T2 + T9 ( Fipronil + Tebuconazole) 41.50± ± T2 + T10 ( Fipronil + Difenconazole) 41.50± ± T2 + T11 ( Fipronil + Chlorothalonil ) 45.00± ± T2 + T12 ( Fipronil + carbendazim) 53.00± ± T3 + T7 ( Thiodicarb + Hexaconazole) 45.00± ± T3 + T8 ( Thiodicarb+ Propiconazole ) 53.00± ± T3 + T9 ( Thiodicarb + Tebuconazole) 45.00± ± T3 + T10 ( Thiodicarb + Difenconazole) 48.50± ± T3 + T11 ( Thiodicarb + Chlorothalonil ) 59.50± ± T3 + T12 ( Thiodicarb + carbendazim ) 59.50± ± T4 + T7 ( Chlorfenapyr + Hexaconazole ) 45.00± ± T4 + T8 ( Chlorfenapyr + Propiconazole ) 45.00± ±

10 33 T4 + T9 ( Chlorfenapyr + Tebuconazole ) 45.00± ± T4 + T10 ( Chlorfenapyr + Difenconazole ) 41.50± ± T4 + T11 ( Chlorfenapyr + Chlorothalonil ) 48.50± ± T4 + T12( Chlorfenapyr + Carbendazim ) 59.00± ± T5 + T7 ( Novaluron + Hexaconazole) 45.00± ± T5 + T8 ( Novaluron + Propiconazole ) 45.00± ± T5 + T9 ( Novaluron + Tebuconazole ) 41.50± ± T5 +T10 ( Novaluron + Difenconazole ) 28.00± ± T5 + T11 ( Novaluron + Chlorothalonil ) 38.50± ± T5 + T12 ( Novaluron + Carbendazim ) 48.50± ± T6 + T7 ( Monocrotophos + Hexaconazole ) 41.50± ± T6+ T8 ( Monocrotophos + Propiconazole ) 41.50± ± T6 + T9 ( Monocrotophos + Tebuconazole ) 35.00± ± T6 + T10 ( Monocrotophos + Difenconazole ) 38.00± ± T6 + T11 ( Monocrotophos + Chlorothalonil) 41.50± ± T6 + T12 ( Monocrotophos + carbenda zim ) 49.50± ± Water spray 76.00± ± No spray 80.50± ±11.1 Mean of two replications; Figures in parenthesis are angular transformed values According to Dunnetts,* indicates significant difference over control at 5 % level. Between Groups Within Groups Sum of Squares ANOVA (Leaf spot) df Mean Square F-value p-value Total ANOVA (Rust) Sum of Squares df Mean Square F-value p-value Between Groups Within Groups Total

11 REFERENCES Kennedy F J S, Rajamanickam K, Lourduraj A C and Mylswami V Compatibility of insecticides and fungicides in groundnut. Groundnut News 4:2-6. McDonald D and Subramanyam P Early and late leaf spots of groundnut. Information bulletin No.21, ICRISAT, Patancheru , Andhra Pradesh. Nene, Y.L. and P.N. Thapliyal, In Fungicides in plant disease control. pp: 691, Oxford & IBH 5: Publishing Company (P) Limited. New Delhi. Vijaya Bhaskar A, Parakhia A M and Patel S V Compatibility of fungicides and insecticides for management of groundnut tikka disease (Early leaf spot and late leaf spot) in Saurashtra region. Indian Journal of Plant Protection.40 (3) : Subramanyam P, McDonald D, Waliyah F and Reddy I J Screening methods and source of resistance to rust and late leaf spot of groundnut, ICRISAT, Information Bulletin, No.47: 2-4, pp.20. [MS received 24 September 2014; MS accepted 18 December 2014] Disclaimer: Statements, information, scientific names, spellings, inferences, products, style, etc. mentioned in Current Biotica are attributed to the authors and do in no way imply endorsement/concurrence by Current Biotica. Queries related to articles should be directed to authors and not to editorial board