50 DEPAETMENTAL REPORTS. 



ing the work resigned early in the year to accept a more remunerative 

 position in Japan, as stated in our last report. His final work here 

 resulted in the discovery of a new enzym, and a report on this was 

 published, this being his third report on the investigations. The work 

 will now be resumed, two experts having been appointed to carry it 

 on, in cooperation with the Bureau of Soils. It is expected that many 

 valuable facts will be brought out during the current year. The 

 so-called mosaic disease of tobacco was worked out during the year, 

 and a paper in regard to it is now ready for publication. The breed- 

 ing of new strains of tobacco is discussed under " Plant breeding." 



TRUCK AND GARDEN CROPS. 



Spraying experiments were carried on during the past year with a 

 view to controlling tlie tomato blight mentioned in the last annual 

 report and were successful, the work showing that the disease, which 

 causes large annual losses, can be easily and economically controlled. 

 Laboratory investigations of the wilt disease of the cowpea and water- 

 melon were continued. As the former is one of the most important 

 rotation crops of the cotton and truck areas, it is very desirable that 

 we determine whether the method of selection which promises success 

 in controlling the cotton wilt may not also be effective for wilt of this 

 and other crops. The results so far obtained are very encouraging. 

 A similar wilt of cabbage, which is very widespread throughout the 

 South and very injurious, has been studied, and we will probably 

 soon be able to recommend methods of preventing it. A great many 

 diseases of other truck and garden crops have been called to our 

 attention, and it is planned to work out remedies for these also the 

 coming season. 



During the year we collected from all parts of the country and from 

 Porto Rico a large number of varieties of sweet potatoes, for the 

 purpose of determining the comparative merits as regards adapta- 

 bility for shipping, disease resistance, productiveness, etc. Duplicate 

 experiments with the collection are being carried on at College Park, 

 Md., and Tarboro, N. C, in cooperation with the agricultural experi- 

 ment station and the State Board of Agriculture, respectively. The 

 experiments will be continued and enlarged the coming season, and 

 will include a study of storage and other questions connected with 

 this crop. 



GREENHOUSE CROPS. 



During the j^ear our investigation of carnations, lilies, violets, and 

 other greenhouse crops has been continued in cooperation with other 

 branches of the Department, watering, feeding, and ijropagation 

 receiving careful attention. Much valuable information on these 

 subjects has been collected, and it is hoped to bring this together in 

 the form of a bulletin at an early date. The work along these lines 

 will be continued and enlarged. Plans have already been made for 

 carrying on a special study of diseases of the rose. 



DISEASES OF THE SUGAR BEET. 



The serious sugar beet blight whicli causes severe losses in Cali- 

 fornia and Colorado, as mentioned in the previous annual report, has 

 appeared to some extent in Nebraska the present season. The results 



