Plant Sanitation, 



312 



[October, 1910. 



Scale Bugs on Cotton. 

 The cotton plots at the Experiment 

 Station have been seriously attacked by 

 two species of Coccidse, — Lecanium nig- 

 rum and Davtylopius virgatus. 



The ' Cheroot Beetle.' 



The small beetle (Lasioderma testacea), 

 variously known as ' cheroot beetle ' or 

 'cigarette weevil', is an extremely difficult 

 pest to eradicate when once it has estab- 

 lished itself in any building. 1 have re- 

 cently examined some tobacco storing 

 sheds in which this insect is responsible 

 f >r considerable loss. The beetles were 

 present both in the cured leaf and in the 

 manufactured cigars. It is believed that 

 the insect lays its eggs on the leaf and 

 that they hatch out and complete their 

 transformations after the leaf has been 

 rolled up into cheroots. The beetle subse- 

 quently bores its way out, leaving a hole 

 in the wrapper of the cigar. Thousands 

 of cigars had been ruined in this manner. 



The only practicable treatment is to 

 fumigate the infected sheds with Carbon 

 Bisulphide. And for this to be effective, 

 it is essential that the sheds should be 

 rendered gas-tight by the addition of 

 ceilings made of tongued and grooved 

 boarding. The Bisulphide is exposed in 

 shallow vessels which must be placed 

 above the material to be disinfected, for 

 the fumes are heavier than air. For 

 permanent stores, it is advisable that 

 all windows and ventilators should be 

 screened with the finest wire gauze, and 

 that the doors should be made to fit flush 

 against their frames, to prevent reinfec- 

 tion of the premises. All waste tobacco 

 should be destroyed at once. If allowed 

 to accumulate, it will afford a breeding 

 ground for the pest. If only a compara- 

 tively small quantity of material requires 

 disinfection, it may be treated in air- 

 tight bins. One pound of the Bisulphide 

 should be used for every thousand cubic 

 feet of enclosed space, and in similar 

 proportion for the fumigation of smaller 

 enclosures. The unpleasant odour of the 

 chemical is not persistent, but disappears 

 on the exposure of the material to the 

 air. It must be remembered that the 

 fumes of Carbon Bisulphide are highly 

 inflammable and explosive. No light of 

 any kind (even that of a burning pipe 

 or cigar) should be brought into a room 

 that has been fumigated before the latter 

 has been thoroughly ventilated. 



This same insect attacks many other 

 stored products. It has been reported 

 to be destructive to dried chillies, and I 

 have recently received specimens that 

 are infesting and causing considerable 

 damage to manure-cake. Manure mills 

 and sheds are not usually constructed 



on a plan that will permit of effective 

 fumigation. In such cases it might be 

 possible to incorporate some unpalatable 

 or poisonous substance into the manure- 

 cake that would not affect its manurial 

 value. 



THE OUTBREAK OF BLISTER 

 BLIGHT ON TEA IN THE DARJ EE- 

 LING DISTRICT IN 1908-1909. 



By W. McRae, m.a., b. sc., 

 Offg. Imperial Mycologist. 



(From the Agricultural Journal 

 of India.) 



In June 1908, near the head waters of 

 the Balasan River, leaves of the tea 

 plant were observed to be attacked by 

 Blister-Blight. Gradually the blight 

 spread from garden to garden, and in 

 October it was noticed on gardens on 

 the Tukvar slopes. This was the first 

 appearance of blister-blight in *the dis- 

 trict of Darjeeling. The disease is not 

 a new one on the tea plant, but hitherto 

 it has been confined to the Brahmaputra 

 Valley in Upper Assam, where it was 

 investigated and described by Sir G, 

 Watt in 1895. It has existed in that 

 region for over 40 years. These two 

 places are widely separated, yet the 

 blight has not been reported from any 

 of the intervening tea districts of Cachar, 

 Sylhet or the Duars. In this year it 

 did not do much damage and in the cold 

 weather died down. 



In 1909 the blight appeared again but 

 earlier in the season, viz., in March, 

 During the summer it showed for the 

 fiist time on other gardens. Everywhere 

 it spread rapidly till hardly a garden in 

 this part of the district is now free from 

 blight. 



The first indication of a blister is a 

 small, pale green, yellow, or pinkish 

 translucent spot easily seen against the 

 darker green of the rest of leaf when 

 it is held up to the light. Sometimes the 

 pinkish tinge fades or it may never be 

 discernible. In other cases the spot is 

 deep red on both sides like red ink, and 

 the red tinge remains even when the 

 spores are ripe. The circular spot en- 

 larges, usually reaching a diameter of 

 I to \ an inch. On the upper side of 

 the leaf the spot gradually becomes 

 depressed into a shallow cavity and on 

 the under side it bulges out slightly, 

 thus forming the blister from which the 

 blight takes its name. The upper con- 

 cave circular area is smooth and shining 

 and the colour is usually paler thau the 

 rest of the leaf, The under convex sur- 

 face, on the other hand, is dull and at 



