274 



Andrews (E. A). Reduction and Retrenchment from the Entomo- 

 logical Point of View. — Qtrlv. Jl. Scicnt. Dept. Ind. Tea Assoc, 

 Calcutta, 1920, pt. iv, pp. 135-143. [Received 4th April 1921.] 



As the Scientific Department is at present considering means of 

 reducing output and decreasing expenditure on tea estates, it is 

 important to remember the effect that this poHcy will have on insect 

 enemies of the plant. If retrenchment is carried out carelessly, damage 

 is bound to accrue. One fundamental fact to bear in mind is that 

 when allowed to grow in its natural way, with the object of producing 

 seed, tea can and does successfully resist insect attack, but when 

 stimulated to produce unnatural leaf conditions, much of its natural 

 power of resistance is lost. It has been observed in America that 

 fruit trees that are allowed to remain in a state of nature for a year 

 or two are able to throw off the attacks of certain scale-insects until 

 they are almost free from them. When brought back into cultivation, 

 they are able to yield heavy crops for four or five years, after which the 

 scale-insects again get the upper hand. It is suggested that such a 

 policy, modified to suit the circumstances, might be advantageously 

 pursued in the case of estates suffering from mosquito blight [Helo- 

 peltis]. Badly affected areas might be left unpruned, unplucked and 

 uncultivated either wholly or in part, but should not be abandoned. 

 The centres of the bushes might be plucked lightly, and the jungle 

 should be cut with the sickle at times to admit light and air to the bushes. 

 Such a rest would increase the powers of resistance against sucking 

 insects. On these areas, also, prunings should be burnt, not on the 

 roadside, but between the lines of tea. It has been observed that land 

 on which fires have been lighted previous to planting with tea gives 

 remarkably vigorous plants ; this seems to indicate that the partial 

 ■sterilisation of the soil produced by the heat of the fire is beneficial. 

 The practice of taking off young shoots and buds before the mosquito 

 blight attacks them is condemned, as this gives the plant no rest or 

 •chance to resist. 



These suggestions are merely experimental, and are only advocated 

 in abnormal circumstances such as the present. One danger is the 

 advantage given to pests over which considerable control is normally 

 exercised by pruning and cultivation, such as borers, loopers, faggot 

 and bag-worms and termites. On accoimt of these, a certain amount 

 of hoeing and pruning is obligatory. Branches that are infested with 

 termites but are still able to bear some leaf are frequently left on the 

 bush, and this enables the termites to extend their depredations for 

 another season. Under present conditions such branches should be 

 removed when pruning. 



In the majority of gardens the necessary reduction in crop will 

 probably be effected by finer plucking. This can be done either by 

 plucking as soon as the leaf is ready, or by plucking out the finer 

 portions of more mature leaf, leaving the remainder on the bush. As 

 the former method forces the bush more than the latter, it permits 

 such pests as red spider, tea mosquito and green fly to have a greater 

 eft'ect on the plant, and is therefore not recommended. Again, 

 cheaper pruning implies bad workmanship and encouragement to 

 bark-eating and other borers and termites. Any saving in expenditure 

 should be made on the high-pruned sections and not on the low and 

 medium-pruned areas. Reducing the processes of hoeing or neglecting 

 to fork round the bushes will undoubtedly result in an increase of 



