17 



in the same soil, and induce a diseased condition, from which 

 the plant will never completely recover. Plants with injured 

 roots are more than commonly susceptible to attack. 



The sowing of seed on fresh or burned plant beds, the 

 avoidance of injury to roots in transplanting or in cultivation, 

 and the making of conditions favourable to a steady, even 

 growth , appear at present to be the only things within reach of 

 the planter for the prevention or moderation of this condition. 



Seed from diseased plants should not be saved, for, while 

 the disease may not be carried in this manner, still an inherited 

 tendency to this condition may be transmitted. 



"FROG EYE," OR LEAF SPOT. This disease is also called 

 "' white speck," because of its appearance in the form of small 

 white specks in the tissue of the leaf. It appears to a certain 

 extent in nearly all tobaccos, and does not do any large amount 

 of damage. A few years ago cigar tobacco with this specking 

 was in demand, but the style changed as soon as it was found 

 possible to artificially produce this marking on any leaf. It is 

 supposed by some to be caused by too much water at the tap 

 root, and by others to be due to the presence of an excess of 

 potash in the soil. It does not appear, however, that it is due 

 to either of these causes, and is probably bacterial in its nature. 

 This specking must be differentiated from the small white 

 specks due to sun burning where there has been a particle of 

 sand upon the leaf. No successful treatment is yet known. 



TOBACCO MILDEW. The most prevalent and injurious 

 disease of tobacco in Southern Ehodesia is that which is 

 variously termed by the planters " mildew," " mould," or 

 white rust." This disease makes its appearance in the form 

 of a white, downy growth on the leaves, usually attacking the 

 lower leaves of the plant first of all. It flourishes especially 

 under conditions of dampness, crowding and insufficient air : 

 hence it is generally more prevalent on Turkish leaf than on 

 Virginian, but Virginian is also attacked to a serious extent. 

 When it has once put in an appearance it spreads rapidly under 

 favourable conditions, and if not checked is liable to ruin a con- 

 siderable quantity of leaf. Leaves attacked by this fungus are 

 quite useless for curing, and it is waste of time to reap them. 

 They are said to turn black in the curing barn. 



