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 CULTURAL
OPERATIONS such as plucking, pruning, shade regulation and weed control can be manipulated to reduce the incidence of pests. Tea mosquito laid eggs on the broken ends (stalks) of plucked shoots. Intensive removal of stalks during plucking will reduce the incidence of this pest. Weeds offer excellent hiding places and serve as alternate hosts for Helopeltis . Growth of weeds and wild host plants in and around tea fields may be controlled which will help to reduce the incidence of this pest.
Severity of attack by shot hole borer increases with the age of the field from pruning. Therefore, it is advised to maintain the length of pruning cycles to 4 years in mid elevation areas. Application of higher rate of K2O @ 1:2 ratio to the soil in the first year of the pruning cycle significantly reduced the infestation by shot hole borer. Populations of leaf folding caterpillars such as flushworms and leaf rollers can be suppressed by manual removal during harvest.
BIOCONTROL
AGENTS Minor status of many of the tea pests is mainly due to the influence of the biocontrol agents. So far, more than one hundred species of predatory and parasitic insects and mites have been reported from the tea estates of southern India. Data are also available on the bioecology of the major parasitoids and predators. An exhaustive list of natural enemies of tea pests is available in Journal of Plantation Crops, 2001, 29 (2): 1-10.
 USE
OF BOTANICALS Formulations containing azadirachtin have been found effective against pink and purple mites and caterpillar pests such as flushworms and leaf rollers. Use of these neem formulations are recommended mainly to save natural enemies and to reduce the load of synthetic pesticides on tea. The studies conducted by the RENPAP in association with the Agricultural Universities have shown that neem kernel aqueous extract (NKAE) is effective against a number of pests attacking field crops. The new formulation is reported to be more potent against different types of pests, than the other conventional neem formulations due to the type of formulation which facilitates the retention of all active ingredients that are present in the neem seeds in the natural proportion and also the usage of correct type of emulsifier. Although the knockdown effect is not reported in the neem products, it may act as a strong repellent, feeding inhibitor, and growth inhibitor, ovicidal and ovipositional deterrent against insect pests. With the help of a project funded by the ministry of Chemicals and Fertilizers, Govt. of India, Neem Kernel Aqueous Extract (NKAE) was evaluated against the red spider mite, leaf roller, flushworm and tea mosquito, infesting tea. Based on the preliminary results obtained from the lab bio-efficacy experiments, micro-plot and large scale field trials were conducted. The results indicated that NKAE @ 5.0% concentration was effective against red spider mite. In the case of leaf roller and flushworm, application of NKAE significantly reduced the population build-up when compared to untreated control. However, NKAE @ 5% concentration was not effective against tea mosquito. The effect of NKAE on non-target organisms like natural enemies of red spider mite was also evaluated. Phytotoxicty and tainting properties of NKAE on tea leaves and made tea, respectively were also tested. NKAE was not phytotoxic to tea. Application of NKAE to tea bushes did not impart any undesirable taint to made tea.
USE
OF INORGANIC COMPOUNDS, HYDROCARBON OILS
Formulations of sulphur are effective against all types of mites, including RSM. Spray oil from paraffinic base is found effective against red spider mites. Since this oil does not leave any residues in tea, it is incorporated into the mite control programme in tea, in organic tea gardens.
INTEGRATED
PEST MANAGEMENT (IPM) During the last one decade, we have made considerable efforts to incorporate non-chemical control strategies and to evolve an integrated pest management programme for tea. The package of IPM practices for tea has been presented at the National Workshop, organised by the Directorate of Plant Protection, Govt. of India and the same has been published in the Planters Chronicle April 2002 issue 98 (4) : 107-125). |
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