INCIDENCE OF HELOPELTIS INFESTATION IN POPULAR TEA CLONES OF NORTH-EAST INDIA IN RELATION TO AGRO-CLIMATIC CONDITION
|Shaheen Shah*1, RNS Yadav1 and PK Borua2
|Corresponding Author: Shaheen Shah, E-mail: [email protected]|
|Received: 20 November 2014 Accepted: 01 December 2014|
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Tea (Camellia sinensis) the most popular cash crop of North East India is attacked from past to recent times by a major insect pest, Helopeltis theivora (tea mosquito bug).The incidence of pest attack on the four commonly used tea clones of North East India viz, TV1, TV23, S3A3 and Tinali was correlated with climatic conditions (temperature, rainfall, humidity) and soil conditions (pH, organic carbon, sulphur, potash) during the period 2011-2013. A study was carried out on 4 popular clones (TV1, TV23, S3A3, Tinali) planted at 7 tea gardens located at Dibrugarh district, Assam, India during the period 2011-2013 to investigate the relationship of pest incidence with climatic conditions and soil conditions. Monthly attack of pest were recorded from 7 tea estates throughout the year (divided into 4 rain flush) of seasons. The meteorological data was collected for the study from Meteorological station, TRA, Dikom, India for the period of 3 years. The insect infestation was severe during 2nd and 3rd flush while lower during 1st and 4th flush. Climatic parameters viz, temperature, rainfall, humidity was found to be positively correlated to helopeltis infestation (with correlation coefficient r= 0.621, r=0.796, r=1 respectively).The soil collected from infected and non infected tea plants was analysed for their organic carbon %, available sulphur, available potash and pH level. Results of organic carbon, sulphur, potash showed that the infected soil samples are either having higher or lower level than the required amount which indicated that imbalanced nutrients might be the reason for helopeltis infestation. While pH level was found to be in same acidic range for both infected and noninfected soil. As pest population vary with changes in climatic parameter, this study might be informative in using the right doses of pesticides as well as maintaining soil nutrients to minimize the pest attack in tea.