DIVISION OF VEGETABLE PHYSIOLOGY AND PATHOLOGY. 53 



that iiw lru<^ causo of fermentation is not the action of bacteria, as 

 formerly supi^osed, bnt of chemical ferments produced by the tobacco 

 plant itself. This discovery has suggested important modifications of 

 the old methods, i)romising much improvement in Northern cigar leaf 

 tobacco. A careful physiological study of Connecticut leaf tobacco 

 has also been made during the year. A third and new oxidizing 

 enzj'm, or ferment, which probabl}^ plays an important part in tlie 

 fermentation process, has been discovered. It was found that tliese 

 ferments were often injured or destroyed by some of the methods of 

 curing and fermentation practiced, and that as a result the finished 

 leaf is of jjoor quality. Tlie method of correcting these errors has 

 been clearly pointed out, but much still remains to be done, and the 

 associate detailed to the work. Dr. Oscar Loew, will continue the 

 investigations in cooperation with the Division of Soils. 



DISEASES. 



Considerable attention has also been given to the diseases of tobacco. 

 The one known as "mosaic" or "calico" is tlie most AA'idespread and 

 injurious, sometimes causing a loss of about 10 per cent of the crop. 

 It occurs throughout the tobacco-growing regions of the world and 

 has been studied by manj^ investigators, especiallj^ in Europe, but as 

 yet the cause has not been found and no remedy is known. Though 

 the study of the disease has not been completed, new facts have been 

 discovered which we believe will lead to the solution of the problem. 



PACIFIC COAST WORK. 



During the year the work on the Pacific coast was continued along 

 much the same lines as heretofore. A great deal of the time of the asso- 

 ciate in charge of this work, Mr. Xewton B. Pierce, is necessarily taken 

 up with correspondence and other routine matters. In accordance 

 with the plan set forth in my last report, he came to Washington, D. C. , 

 during the year and spent several months here preparing a bulletin on 

 peach leaf curl and investigating other matters of particular interest 

 to the Pacific Coast States. The bulletin gives the results of investiga- 

 tions and exi^eriments with peach leaf curl for a number of years, and 

 shows conclusively that it can be readily prevented at comparativelj^ 

 small expense. Widespread interest has been manifested during the 

 year in a serious disease of the apple in Washington State, and consider- 

 able attention was devoted to a study of this trouble. During the lat- 

 ter part of the year manj' complaints have come from California and 

 other Western States regarding a serious disease of sugar beets. It 

 is estimated that the loss in California alone from the disease in ques- 

 tion was over §2,000,000 last year, and the trouble seems to be spread- 

 ing. In order to obtain some information as to the nature of this 

 trouble the associate in charge of the work was directed to visit the 

 infected regions and confer with large growers wherever it was found 

 desirable to do so. As yet there is no information at hand as to the 

 probable cause of the trouble, but it is hoped that facilities can be 

 afforded for undertaking a thorough study of this matter at an early 

 day. Other work has been done in the matter of crossing graj)es with 

 a view of obtaining some hardy and resistant varieties, but this has 

 been referred to under plant breeding. 



