ISBN: - 978-93-88936-09-5 steep cut leads to the wastage of bark when tapping reaches the base of the tree and too flat a cut leads to overflow of latex. The latex vessels in the bark run at an angle of 3-5˚ to the right and therefore an opposite cut from high left to low right will open more latex vessels. To avoid spillage, an inward slope towards wood also has to be maintained on the tapping cut. 4 .5 (C) Standard of tapping and height of opening In India, the best period to open new areas for tapping is March-April. The trees left behind during the season due to want of sufficient girth may be opened in September. In the immature phase annual growth rate is around 7cm, whereas it will be 2cm or less under tapping. Hence, trees of lower growth than recommended should not be opened for tapping. 4 .5 (D) Tapping depths, bark consumption and bark renewal The best yield is obtained by tapping to a depth of less than one millimetre close to cambium since more latex vessels are concentrated near the cambium. Shallow tapping results in considerable loss of crop. To obtain optimum yield, care should be taken not to injure the cambium at the time of tapping. 4 .5 (E) Time of tapping, task and utensils It is necessary to commence tapping early in the morning as late tapping reduces the exudation of latex. The tapping task (number of trees tapped on a day by one tapper) in India is around 300-400 trees compared to 400-500 trees in other countries. Headlights can be used for early morning tapping during non-rainy season including summer months to extract better crop. Competing tapping with its latex flow in the early hours (02.00 to 6.00 hrs) favours better production during summer and in wind prone areas. 4 .5 (F) Tapping systems There is a response to different tapping systems varies from clone to clone. Since majority of rubber area is with high yielding clones, in general, rubber trees are to be tapped on half spiral third daily (S/2 d3) system. 1. Low frequency tapping (LFT) Trees under low frequency tapping (d3, d4, d6 or d7) have to be stimulated from opening for maximum sustainable yield. Numbers of stimulation vary with clone, age of the tree, tapping system and frequency. In high yielding clones like RRII 105 and PB 217 under third daily (d3) tapping frequency with weekly one day regular off, yield increase can be achieved by three annual stimulations (April and May, September and November. Low frequency tapping (LFT) with stimulation can be practised from the first year of tapping. 2. Controlled upward tapping (CUT) 104
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