BUREAU OF PLANT INDUSTRY. 51 



of the investigations in California, Colorado, Kansas, and Iowa indi- 

 cate that this particular blight is not of parasitic origin, but that it is 

 due to a lack of sufficient moisture to meet the demands of excessive 

 evaporation from the foliage. Beets affected with this disease become 

 hard and woody and the young feeding roots and taproot are destroyed. 

 An expert pathologist has been appointed to carry on investigations 

 of the diseases of the sugar beet, and his entire time will be devoted 

 to this work during the next two or three years. We are in constant 

 receipt of requests for information in regard to these diseases from 

 all important beet-growing regions. A report on the particular blight 

 above mentioned will be published during the current year. 



WORK IN THE PACIFIC COAST STATES. 



Bacteriosis of walnuts. — Three lines of work on this disease have 

 been carried on during the year: (1) Extensive spraying experiments 

 for the purpose of preventing the disease in orchards already estab- 

 lished. Some of the sprays tested resulted in a large saving of nuts, 

 while others gave no positive results. (2) Selecting from seedling 

 orchards resistant trees, which embody the character of fruit and 

 habit of growth most desired, and from which nursery stock may be 

 budded or grafted. One variety has been found which answers these 

 requirements and others will certainly be obtained when the field can 

 be thoroughly explored. (3) Breeding of resistant varieties, which 

 includes the crossing of hardy varieties of Juglans regia and hybrid- 

 izing this with other species of Juglans which appear to be free from 

 the disease. Considerable work in this line has already been done, 

 and as a practical result a hybrid root has been found which has such 

 great hardiness, notwithstanding unfavorable soil conditions, that it 

 will be used as a stock upon which to graft the disease-resisting vari- 

 eties of Juglans regia when selected from the orchards. Its vigor 

 and hardiness are such that it bids fair to increase threefold the 

 possible successful commercial walnut culture of the Pacific coast, 

 and will eventually represent a great financial gain to the industry. 

 The work on bacteriosis will be continued on the lines above men- 

 tioned, and a large amount of field work will be necessary in the 

 treatment of groves, the study of the comparative resistance of trees, 

 the crossing and hybridizing of tens of thousands of nuts, the propa- 

 gation of trees from the nuts obtained from the work of the past 

 spring, the testing and grafting of stocks, etc. This growing and 

 grafting of stocks and hybrids calls for land, and it is hoped that this 

 requirement may be met in some satisfactory way. During the year 

 we hope to make a collection of nuts of all species of Juglans and of 

 all well-marked types of Juglans regia, so that a direct comparison 

 may be made of the varieties, and that the different wild species may 

 be on hand for the hybridizations planned. 



Pear blight — This bacterial disease of pomaceous fruits has now 

 become well established in many parts of California and the North 

 Pacific States. It has been found that the infection of fall bloom 

 and the tender growth at the base of the main limbs has resulted in 

 the death of more trees in California than is caused by the common 

 spring infection. By preventing such bloom and growth from develop- 

 ing at the base of the main limbs, where it is not required for the 

 production of fruit, a leading source of the infection of the more 

 vital parts of the tree is removed. As the disease is prevalent in 

 orchards where colonies of bees are kept in the vicinity, it has been 



