BUREAU OF PLANT INDUSTRY. 287 



of recent introduction, has greatly increased during the past two 

 years and will require study to perfect means of control. A new 

 disease, potato wart, is spreading in Europe, and there is great danger 

 of its introduction into this country. 



IMiscELLANEOus DISEASES OF TRUCK CROPS. — The ncw and dangerous 

 Michigan bacterial blight of tomatoes, now being studied in the lab- 

 oratory by Dr. Erwin F. Smith, is the subject of experiments for con- 

 trol in the field. ]\Ialnutrition problems are being continued along 

 the lines outlined in previous reports, and various other diseases of 

 truck crops are being studied. 



Breeding rust-resistant asparagus. — The work of breeding an 

 asparagus resistant to rust has progressed favorably. Several thou- 

 sand pedigreed seedlings from resistant parents are now growing at 

 Concord, Mass. The most progressive farmers in that region are 

 undertaking breeding -work on their own farms, following the meth- 

 ods outlined by this Bureau. 



Sugar-beet diseases. — Studies upon diseases of the beet have pro- 

 gressed favorably. The Cercospora leaf-spot has prevailed to a seri- 

 ous extent in the Arkansas Valley of Colorado and Kansas. The 

 Department has been able to control this disease in jNlichigan and is 

 now extending its experiments to the West. Studies of the curly-top 

 of the beet are being continued in the West to learn more of the nature 

 of the disease, and, in cooperation with the Bureau of Entomology, 

 to develop methods of controlling the leaf-hopper which causes it. 

 Several other beet diseases are receiving attention. 



Sugar-beet improvement. — The breeding of beets for increased 

 sugar yield, for the production of xVmerican seed, for the development 

 of single-germ seed, for the production of alkali-resistant and early 

 and late maturing strains, and to develop other desirable characters 

 are lines of work that have been continued during the past year. 

 They are essential to the success of the American sugar-beet industry 

 and must be carried out on a large scale, as they require a more exten- 

 sive equipment than most breeding problems. 



Sugar-beet culture. — A beginning has been made in the study of 

 beet nutrition, but many problems regarding methods of planting, 

 thinning, culture, and the technique of beet growing are yet to be 

 solved. The working out of these problems will contribute largely 

 toward the lessening of the cost of beet production and will load to a 

 great increase in the acreage grown. The most desirable rotations of 

 crops and the best methods of improving the soil for beets are being 

 studied. Fundamental investigations upon a comprehensive scale 

 alone these lines are essential. The fullest cooperation is tendered 

 the Department by the various beet factories and there is a great 

 demand for an extension of the work. 



SOIL BACTERIOLOGY AND WATER-PURIFICATION INVESTI- 

 GATIONS. 



The investigations of the Bureau bearing upon general soil bacteri- 

 ology-, the use of nitrogen-fixing bacteria for inoculating leguminous 

 crops, and the improvement of farm water supplies have continued 



