Drugs and Medicinal Plants. 



324 



[April 1908. 



throughout the year. Treatment.— The 

 tobacco fields should be kept clear of 

 weeds. Iu no other way will it be possi- 

 ble to keep tobacco free from " ash." 



Curled Leaves.— These are known as 

 suruttal. The edge of the leaf is usually 

 curved in towards the under surface, and 

 the green portions between the veins 

 bulge out as though they had outgrown 

 the spaces allotted to them. This crump- 

 ling is caused by swellings on the veins ; 

 these can be seen on the under-surface 

 of the leaves. There seems no reason to 

 suppose that these are due to insects or 

 fungi. These leaves are quite unsale- 

 able, and, therefore, the plants which 

 produce them are often kept for seed. 

 This practice cannot be too strongly 

 condemned. 



Mosaic Disease.— The affected leaves 

 are yellowish green in patches, so that 

 the leaf is mottled with light and dark 

 green. In some cases the form of the 

 leaves is altered, and they become strap- 

 shaped, about 12 inches long, but only one 

 or two inches wide ; these narrow leaves 



are often yellow with green veins. On 

 some leaves the patches are quite white 

 and more angular. These three appear- 

 ances are known by the growers under 

 different names, but they are regarded in 

 other countries as only forms of the same 

 disease. It has been shown that the 

 disease is contagious, but not infectious ; 

 it can be transferred by first handling a 

 diseased plant and then a sound one. 

 The burning qualities of " mosaic " leaves 

 are poor ; they burn with a disagreeable, 

 penetrating odour, and therefore cannot 

 be used for pipe tobacco. Possibly the 

 presence of mosaic disease accounts for 

 the flavour of Ceylon tobacco ; it must 

 be remembered that affected leaves do 

 not wither, but are harvested and cured 

 with the good ones. Tobacco is free 

 from this disease when it is grown on 

 newly-cleared jungle land, but the disease 

 always appears after two or three years, 

 when the same land has to be used 

 again. When mosaic disease makes its 

 appearance in a field before topping, 

 care should be taken to top all the 

 healthy plants before touching the 

 diseassd ones. 



