Kirubakaran, D.

Muraleedharan, N.

Satheshkumar, A.

English

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A. Satheshkumar,  D. Kirubakaran and N. Muraleedharan388Short  scientific  report Journal of Plantation Crops, 2011, 39 (3): 388-389Black tea, manufactured from the tender shoots ofCamellia sinensis (L) O.Kuntze is consumed all over theworld.  India is the major producer, consumer andexporter of black tea in the world. Generally, the tea leavesare infested by a wide range of pests and diseases.  Theclimatic factors prevailing in the tea growing areas ofsouth India favour blister blight epidemic duringmonsoon which extends over a period of about six monthsin an year. The disease caused by the fungus, Exobasidiumvexans Massee is controlled by the application of acombination of triazole fungicide and copper oxychloride.The combination of copper oxychloride andhexaconazole - (R,S)-2-(2,4-dichlorophenyl)-1-(1H-1,2,4-triazole-1-yl-hexane-2-ol) is effective in tea blisterblight control (Chandramouli and Premkumar, 1995).Harvesting of tea in India is done by hands, but in southIndia, due to acute shortage of man power, the tea gardensare now resorting to the use of hand-operated shears. Inthis context, the UPASI Tea Research Institute had maderecommendations on harvesting using shears(Swaminathan et al.,1990). Shear harvesting isrecommended only during the high cropping periods.  Theharvesting interval between two successive shear harvestscan be maintained at leaf expansion time (LET) in daysx 1.75 (Muraleedharan and Hudson, 2007). However,when the labour shortage is very severe, estates areextending shearing even to the low cropping period,almost covering the entire year. Plucking interval in theshear harvested fields range from 17/18 to 21/22 days indifferent months.  In view of this, there is a need to studythe impact of shear harvesting on the dissipation offungicides applied during the low cropping periods, whenthe harvesting interval prolongs to 20-21 days. Thepresent study was conducted to determine the residuesof hexaconazole and copper in black tea, manufacturedfrom shoots collected from a field under shear harvestingat an interval of 21 days.Impact of shear harvesting on the residues of hexaconazoleand copper in black tea(Manuscript Received: 18-04-11, Revised: 26-07-11, Accepted: 21-10-11)Keywords: Copper, hexaconazole, residues, shear harvest, teaA non replicated field trial was conducted inUPASI Tea Experimental Farm, Valparai (Tamil Nadu,India) situated at an elevation of 1050 m above MSLduring November 2010 in the north east monsoon period.Plots measuring 100 sq.m contained tea plants of mixedcultivars, planted in double hedge. The treatmentsincluded a combination of hexaconazole 5 EC @ 200mL/ha + copper oxychloride 50 WP @ 210 g/ha as onetreatment (T1) and an untreated control (T2) forcomparison as second treatment. The spray volume was175 l/ha and applied with a hand operated knapsacksprayer. Tea shoots comprising three leaves and a budwere harvested by shear on "0" day (3 h after fungicidespray) and 21st day after the application of the chemical.Three sprayings were given at 7 days interval as per theblister blight disease management schedule. Theharvested shoots were processed in miniaturemanufacturing unit. The drier mouth black tea sampleswere analysed for residues of hexaconazole and copper.Hexaconazole was analysed using gas chromatograph(Varian 3800) and copper content by using atomicabsorption spectroscopy (AAS, Perkin Elmer AnalystA800). The methodology for hexaconazole residueanalysis was that of Manikandan et al. (2006) and coppercontent was analyzed as per Official Methods of Analysisof AOAC International (AOAC 971.20, 18th edition).AAS was calibrated using NIST traceable copper standardsolutions and the analysis was carried out at 324.8 nmresonance line.Gas chromatographic analysis was carried out withVarian 3800 gas chromatograph coupled with thermionicspecific detector using DB-608 column (Crossbond 50%phenyl-50%methyl poly siloxane). The operatingconditions were as follows: detector temperature 260 °C,injector temperature 240 °C, oven temperature program,1.0 min. at 190 °C, 5 °C/min. to 225 °C held for8.0 min., 10 °C/min. to 240 °C held for 3.0 min. TheResidues of hexaconazole and copper in black tea389total running time was 20.50 min. The injection volumewas 1.0 µL. Nitrogen was used as the carrier gas andmaintained at a constant flow rate of 3.0 ml/min. Theapproximate retention time of hexaconazole was 13.8min. Method performance was assessed by evaluatingquality parameters such as recovery percentage,repeatability, reproducibility, specificity, limits ofquantification and detection. Linearity was achieved overthe range of 0.1-0.5 mg/kg with a correlation coefficientof 0.999.The residues of hexaconazole and copper contentin black tea on "0" and 21st day are summarized in Table1.interval. It may be pointed out that in their experiment,harvesting was done by hand on 0,1,3,5,7,10 and 14 daysafter fungicide application. The frequent samplingresulted in faster dissipation of hexaconazole and theresidue was less than the limit of quantification on 14thday.  In the present study, fungicides were sprayed thrice,at 7 days interval and the sampling was done by shearharvesting on "0" and 21st day as per the recommendedLET. The persistence of hexaconazole and copper on 21stday indicated that the accumulation of hexaconazole andcopper oxychloride took place in the tender tea shoots.The study revealed that the impact of shear harvestingon the persistence of hexaconazole even on 21st day afterthree sprayings. This points to the need for a relook atthe present schedule of fungicide application to controlblister blight. This may necessitate the extension ofspraying interval leading to reduction in the number offungicide applications. But, the major disadvantage willbe reduced level of blister blight disease control.ReferencesChandra Mouli, B. and Premkumar, R. 1995.  Hexaconazole - a novelfungicide in tea blister blight management.  UPASI ScientificDepartment  Bulletin  48:59-66.Manikandan, K.N., Karthika, C., Muraleedharan, N. Seenivasan, S.and Selvasundaram, R. 2006. Studies on the residues of copperand hexaconazole during their combined application and theirsubsequent transfer into tea infusion. J. Plantn. Crops 34(3):405-409.Muraleedharan, N.  and  Hudson,  J.B. 2007. Tea cultivation in southIndia agricultural Policies, The Planters' Chronicle  103 (1):6-41.Swaminathan, P., Hudson,  J.B., Udayakumar, S., Kandasami, C. andAnand, S. 1990. Guidelines on tea culture in south India.14th edition, pp.195, UPASI, Coonoor.UPASI Tea Research Foundation,Tea Research Institute,Nirar Dam BPO, Valparai - 642 127,Coimbatore district,Tamil Nadusathesh82@gmail.com A. Satheshkumar,D. Kirubakaran,N. MuraleedharanThe results showed that the persistence ofhexaconazole on 21st day was much higher (0.21 mg/kg)than its maximum residue limit of 0.05 mg/kg underEuropean Union (EU). The copper content was on parwith the EU MRL of 40.0 mg/kg and well below theMRL of 150.0 mg/kg prescribed by India. Manikandanet al. (2006) reported that after the combined applicationof hexaconazole and copper oxychloride, the residues ofhexaconazole in black tea on 14th day was less than thedetection limit when two sprays were given at 7 days Table 1. Residues of hexaconazole and copper in black teaDays Residues in mg/kg (T2) Residues in mg/kg (T1)Hexaconazole Copper Hexaconazole Copper0 ND 18.24 1.20 114.6521 ND 18.12 0.21 40.21ND-Non detectableLimit for hexaconazole is 0.05 mg/kgT2 -Untreated control; T1-Hexaconazole+Copper oxychloride (@200 ml+210 g/ha)

Impact of shear harvesting on the residues of hexaconazole and copper in black tea

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Impact of shear harvesting on the residues of hexaconazole and copper in black tea

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