258 Early Studies in Bacterial Plant Diseases 



to the industry here. Thus far it appears to be bacterial in its nature, but 

 as pure culture inoculation experiments have not been completed as yet 

 it is not settled beyond question. Inoculations from impure culture have 

 reproduced typical cases of the disease. It is a disease both of the nut 

 and tree — and the organism which seems to be the cause is a bacillus of 

 medium length. As it is an important matter I hope to give it special and 

 personal attention this spring. 



Reports from Washington are favorable respecting the treatment of the 

 serious apple disease I worked on while north, and which was so beauti- 

 fully reproduced after my arrival at this laboratory a year ago. In due 

 time I will work this disease up for a special bulletin as it is of the deepest 

 interest both from a horticultural and a scientific standpoint. 



The matter of olive culture has occupied my time of late — several 

 diseases are getting a foothold which may in time require more attention. 

 You will see what I have done on the olive after a time ! 



As the walnut trouble is a serious one and as it may be, and quite likely 

 is, a bacterial one I am interested to know what means Mr. Waite suggests 

 for the prevention of pear blight. I suppose it is the spraying of flowers 

 much as with codling moth, but do not know. What do you think of the 

 use of Lysol — the new French treatment.^ Some time when you can, write 

 me about Mr. Waite's treatment. I would like to try Lysol and Corrosive 

 sublimate in some form — though from the way the disease works I question 

 our power to control. 



With a view to developing disease-resistant varieties, later on, 

 both pear and walnut varieties were sought to be introduced into 

 this country, and attempts, which met with partial success, were 

 made by hybridization to solve the economic problems of Pierce's 

 bacterial walnut disease, and pear blight.^^ In California, Pierce 

 obtained walnut hybrids with a fair degree of resistance to disease, 

 and in Oregon, F. C. Reimer, utilizing Asiatic species of Pyrus, 

 got good resistant pear stocks. Moreover, Waite, over a period of 

 years, presented knowledge which showed that, on trunks and 

 limbs of occasional trees, " hold over " patches, which ooze living 

 bacteria, last over winters in pear orchards. By thoroughly eradi- 

 cating these " hold over " spots so that bees cannot have access 

 to them and transmit the bacteria to new blossoms and shoots of 

 the following spring, a control method, tried both in Georgia and 

 California, accomplished real results."^" 



^^ Fifty years of pathology, op. ch., 30, 39. Also, David Fairchild, Plant introduc- 

 tion for the plant breeder, Yearbook of the U. S. Dept. of Agriculture for 1911, 

 op. cit., 411-422, at p. 421. Also, V. B. Stewart, Notes on the fire blight disease, 

 Phytopathology 5(6): 327, Dec. 1915, and cited references to articles on the subject 

 by Reimer and N. E. Hansen. 



^^ Erwin F. Smith, Introduction to bacterial diseases of plants, op. cit., 68. 



