1911.1 PUBLIC DOCUMENT — No. 31. 149 



ABNORMALITIES OF STUMP GROWTHS. 



BY GEORGE H. CHAPMAN. 



For the past few years there have been called to our attention 

 on stump land and burned-over wood lots various malformations 

 and abnormalities of the leaves of sprouts growing from the 

 stumps ; and in connection with other physiological work being- 

 done in the laboratory,- these conditions were studied, with 

 the idea of discovering, if possible, the cause and relationship 

 1o other physiological diseases, such as those arising from mal- 

 nutrition ; also mosaic disease, overfeeding and crdema. 



These diseases are all ditferent in character, but it might be 

 well to give a brief description of them at this point. 



Overfeeding, particularly with nitrates, may be recognized 

 l)y a slight increase in size of leaf, the color 1)eing darker and 

 the leaf stitfer in texture. The cells of the leaf, with the ex- 

 ception of the bundles, are normal in form and are larger, but 

 the bundles are distorted, and this causes a distortion of the 

 leaf, due to the form of the l)undles. The leaf is usually some- 

 what larger than normal, and the distortion curves the edges 

 of the leaf downward, i.e., rolls them toward the under side. 



All investigators agree that the mosaic disease is purely a 

 physiological one, but there seems to be much dou1)t as to 

 whether it is infectious or contagious in character, or both. 

 There seems to be some difference in opinion, also, as to the 

 direct cause of the disease. In tomatoes it is always produced 

 when the vines are heavily pruned, and in the work here it 

 has been sho\vn that it is connected in no way with methods of 

 transplanting the young i)lants, and only results from subse- 

 quent pruning. 



It has been found that tobacco is much more susceptible un- 



• Presented as part work for degree of M.Sc. 



2 Dept. of Veg. Phys. and Path., Mass. Aer. Exp. Sta. 



