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B. K. Bakshi , Y. N. Puri , R. P. Sharma , Sujan Singh , Balwant Singh

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Y. N. Puri

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B. K. Bakshi , Y. N. Puri , Sujan Singh , R. P. Sharma

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Y. N. Puri

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A preliminary investigation on heartwood extractives of SAL and TEAK is reported. The timbers were subjected to various solvents successively and after extraction with each were tested for decay resistance. There was a progressive loss in decay resistance following each extraction, though this loss was different for different treatments and test fungi. It, therefore, appears that the general high decay resistance of both these timbers is due to the combined toxic effect of most of the fractions.

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Y. N. Puri , Sujan Singh , S. N. Khan , B. K. Bakshi

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Results of studies on the natural decay resistance of 5 hardwood timber species, viz., haldu (Adina cordifolia Hook. F.), salai (Boswellia serrata Roxb.), mango (Mangifera indica Linn.), walnut (Juglans regia Linn.) and bahera Terminalia bellirica Roxb.) are reported. In all the species, except walnut, true heartwood is absent or formed only rarely. All are non-resistant against wood-rotting fungi. These findings based on laboratory tests correspond closely with the performance of the species in 'grave-yard' tests.

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Y. N. Puri , S. N. Khan

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Results of studies on the natural decay resistance of sissoo and sandan by soil
block method are reported. While sissoo belongs to very resistant class and exhibits
little or no variation in decay resistance of 'outer' and 'inner' heartwood, sandan
manifests large variations in decay resistance amongst different samples, and within
a sample between 'outer' and 'inner' heartwood. These variations in the latter species are not correlated with heartwood diameter, age of tree or difference in rate of growth of heartwood in the 'outer' aud 'inner' regions.

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B. K. Bakshi , Y. N. puri , Sujan Singh

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Soil-block method for evaluation of natural decay resistance of timber under laboratory conditions is described in detail. Timbers are proposed to be classified into four decay resistance classes based on weight loss per cent in the blocks tested. This classification is based on the weight loss ranges as given in the U.S. Standard: ASTM: Designation: D2017-63, viz. 0-10% (very resistant), 11-24% (resistant), 25-44% (moderately resistant), and 45% and above (non-resistant), with the modification that each class is further divided into 3 sub-c1asses, to distinguish species within the main classes. Decay resistance of heartwood from 21 samples of sal ond 23 samples of teak, both from outer and the inner heartwood regions at the same radius, is tested. Sal heartwood, from outer zones, at the same radius is generally 'very resistant' (Av. Weight loss 0.20-4.19%). Some tendency towards a lesser decay resistance in the inner heartwood zone in quality class I & II sa1 is evident (weight loss 0.24-21.06%). No such difference, however, is evident in Sal trees of quality class III (weight loss 0.10-4,12%). Also, no difference in decay resistance with respect to vertical position of heartwood in the 3 trees of quality class III was noticed. Teak outer heartwood varies in decay resistance from very resistant to 'moderately resistant' (weight loss 1.98-25.63%). In older trees (age or heartwood 54-97 based on ring counts) inner heartwood is less resistant than 'outer' heartwood within the same sample. In younger trees (age of heartwood 11.47 hased on ring count.), entire heartwood of a sample is generally of the same resistance class and compares with inner heartwood of older trees. Variations in decay resistance appear to be correlated with age of trees, rate of growth and radial position of heartwood in the logs.

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B. K. Bakshi , Y. N. Puri

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Dwarf mistletoe is causing economic damage to blue pine, particularly in the low rainfall and arid locations in Himachal Pradesh and Jammu and Kashmir States. Dispersal of the parasite, its mode of infection, symptoms of the disease and damage to the host are described. In high level blue pine forests where incidence of infection is heavy resulting in stunted growth and mortality, it appear. Unprofitable to continue with such stands. It is suggested that such forests be carefully examined and clearfelled wherever feasible from the point of soil and moisture conservation and site maintenance and artificially regenerated. Burning after clearfelling may help regenerations in locations where the disease incidence is low, the disease may be kept in check through sanitation and its spread checked by establishment of a protective zone. These are the usual measures adopted in other countries to control dwarf mistletoe.

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Sujan Singh , Y. N. Puri , B. K. Bakshi

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In dry teak (Tectona grandis Linn. f.) forests in Gujarat state, the present system of coppicing flush with the grouad results in about 50 percent of trees becoming decayed at the end of the rotation. The decay is present in the lower part of the trees and may extend up tn 2-4m on the stem. Any, form of felling, including coppicing, results in injuries through which decay, establishes in the stools. Such decay migrates into callus shoots and high side shoots which constitute about 80 per cent of the present crop, because of the intimate heartwood conneciion established between the shoot and the stool. Low side shoots which constitute about 20 percent of the crop, however, remain free from decay as the heartwood connention with the stool is not established. Coppice teak forests sbould therefore be managed in a way that low side shoots are encouraged to develop and constitute the ultimate crop. Low copplcing results in cutting away of dormant buds which are present at the base of the tree and thus affect the sprouting at that level affecting frequency of low side shoots. In high coppicing, development of callus shoots is inhibited due to rapid drying and shrinkage of wood at the cut surface, causing separation from the bark. Also in high felling in a dry locality, even if the upper part dies the base of the stem remains alive to encourage development of side shoots. Based on the above premises, experiments were laid down in Godhra Forest Div., Gujarat State, where coppicing was done at different heights adjusting coppicing heights from ground leve1 to 25 cm at intervals of 5 cm. Copplcing at 10-15 cm was found ideal when low side soots were encouraged while callus and high side shoots discouraged to develop. Also, at these heights, adequate number of stools with low side shoots became available to select maximum number of low side shoots evenly distributed in the stand. Cleaning in the fifth year as is currently practised may continue as both callus aud side shoots may develop with equal vigour at all ages. It is, therefore, concluded that in dry teak forests, the stool heights may be adjusted at 10-15 cm from ground level and low side shoots selected for raising a healthy coppice crop free from decay.

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