42 



BULLETIN 1256, U. S. DEPARTMENT OF AGRICULTURE. 



der a wide variety of names, panachure being especially used. This 

 is a condition of the leaf in which large bands or irregular areas of 

 the leaves of isolated plants lose their green color, becoming yellow 

 or distinctly white and sharply demarcated from the green areas. 

 This condition is not infectious, but is apparently hereditary. More 

 rarely the entire leaf or part of the plant turns yellow or white, when 

 it is spoken of as albinism or chlorosis. 



A form of curly-dwarf is not unknown in tobacco, but is very rare 

 in this country. In the East Indies and Europe, similar diseases are 

 described as krulzieke and faltenzwerg. In this disease the leaves 

 become markedly stunted and curled. The cause is unknown. 



A streak disease of tobacco apparently of nonparasitic origin has 

 been occasionally noted. A narrow brown line usually extends the 



Fig. 23. — Damage to tobacco from hail and storm. Various degrees of injury result 

 from this cause. An extreme case of injury to shade-gro-wn tobacco is here show a. 



full length of the stalk and into the leaves, following the vascular 

 system and causing wilt and death of the affected leaves. It has been 

 seen most commonly on White Burley tobacco. 



A trouble known as crookneck has been described from North Caro- 

 lina. The plants and leaves are twisted and deformed. The stem 

 and leaves on one side of the plant are usually affected and die or 

 fail to grow, while the growth of the other parts causes the twisting 

 and malformation observed, much as in the case of lightning injury. 



Monstrosities or teratological phenomena are sometimes observed in 

 tobacco as in other plants (fig. 24). These are usually characterized 

 by fasciations, as in the doubling of stalks, midribs, veins, or leaf 

 blades, or in the splitting up of one leaf into two or more apparently 

 distinct parts. 



Crown-gall caused by Bacterium tumefaciens, a fairly common 

 disease on some of the fruits, produces striking tumors on the to- 

 bacco plant by artificial inoculation. As far as known, however, this 

 disease does not occur naturally upon tobacco. 





