214 



The first indication of the disease occurred in July, when, among nor- 

 mally growing trunks, the leaves of some specimens turned yellow and fell 

 off. Nevertheless the terminal buds of the branches developed a vigorous 

 August growth which held most of its foliage until fall. In September the 



outer bark covering split and the 

 surface appeared like yellow ochre 

 velvet beginning at the lowest part 

 of the branch and decreasing in in- 

 tensity toward the tip. Further, 

 the fact is worthy of notice that 

 practically only the luxuriantly 

 growing wild trees appeared to be 

 diseased. The phenomena of the 

 tan were only sparsely noticeable in 

 grafted trees. It was seen at once 

 that branches, where they had re- 

 tained their leaves, had only a few 

 really torn spots in the bark, indeed 

 only closed, warty excrescences, i. e. 

 the younger stages of the disease. 

 In the axils of two year and much 

 older diseased trees, ruptured places 

 in the bark (r) occurred less fre- 

 quently. Usually the individual 

 centres of disease appeared there 

 in the form of very broad, very 

 liigh yellow ochre cushions running 

 crosswise. 



The investigation of these cus- 

 hions and of the broad, ruptured, 

 discolored surfaces on branches one 

 year old showed at once marked 

 correspondence with those on the 

 older ones ; only it could not be 

 seen that the lenticel cushions give 

 ofif any dust. The discolored mas- 

 ses were found to be light brown, 

 cylindrical, wrinkled cork cells with 

 rounded corners, which were broken 

 off individually or in small groups. 

 The branches, giving off this dust, seem with a few exceptions to be 

 otherwise healthy, only their primary bark is ver}-- much broken by the 

 considerable separation of the parenchyma cells. Places with loosened 

 structure are found in the wood as well as in the bark. Cross bands of duct- 

 less parenchyma wood may be noticed in the stages produced toward the 



■k-fv 'Pi'^ 



old clK 1 1 



Onr year old and two year 

 bianrhes with tan cushions 



between the spht bark stripes. (Orig.) 



