1911.1 PUBLIC DOCOIFAT — No. 31. 149 



ABNORMALITIES OF STUMP GROWTHS. 



BY GEORGE H, CHAPMAN. 



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

 on stnmp land and burned-over wood lots various malformations 

 and abnormalities of the leaves of sprouts growing from the 

 sluiu])s; and in connection with other physiological work being 

 done in the laboi-atorj,- these conditions were studied, with 

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

 to other physiological diseases, such as those arising from mal- 

 nutrition; also mosaic disease, overfeeding and o'dema. 



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

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



Overfeeding, particularly with nitrates, may be recognized 

 by a slight increase in size of leaf, the color being darker and 

 the leaf stifFer in t< xture. 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 bundles. 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 he much doubt as to 

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

 Therc^ 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 shown that it is connected in no wav with methods of 

 transplanting the youug plants, and only results from subse- 

 (pient ])rnning. 



It has been found that tobacco is much moi-e snscejitible un- 



' Presented as part, work for degree of M.Sc. 



' Dept. of Veg. Plus, and Path., Ma.ss. .\Kr. Exp. Sta. 



