428 THE MONTHLY BULLETIN. 



VARIATION AND BLIGHT RESISTANCE AMONG 



WALNUTS. 



By L. D. Batchelor, Citrus Experiment Station, Riverside, Cal. 



With the recent propagation of the walnut by grafting and budding 

 it is reasonable to expect that the majority of the varieties thus propa- 

 gated, so early in the development of this industry, is only partially 

 suited to the needs of the walnut grower. IMany of the seedling groves 

 and the older grafted groves are not producing as heavy crops of com- 

 mercial nuts as might be reasonably expected by a close observer of this 

 industry. The nuts from many of the grafted varieties fall consider- 

 ably short of the commercial standard for high grade walnuts. Some 

 of the heaviest bearing varieties, such as the Chase, Prolific and El 

 Monte, produce nuts which cannot be sold in the very best grade of the 

 commercial product. On the other hand, such a variety as the Placen- 

 tia, which produces the most nearly ideal commercial nut, is not a heavy 

 producing variety and is quite as susceptible to walnut blight as the 

 average seedling. Again, the Eureka variety, which seems to success- 

 fully avoid the walnut blight during many seasons by its lateness in 

 coming into bloom, is a very moderately yielding sort. This variety 

 produces an excellent commercial nut, but owing to its shyness in bear- 

 ing is far from an ideal variety for Southern California. The above 

 examples are only a few of many which might be cited to show the 

 shortcomings of practically every variety of walnut now being propa- 

 gated. 



It is not to be expected that an absolutely perfect variety of walnut 

 will be originated, any more than there are perfect varieties of apples, 

 oranges, or other fruits. With the vast expanse of seedling groves in 

 Southern California from which to choose it seems reasonable, however, 

 to expect that possibly some of the choicest individual trees are still 

 to be discovered. It is seldom in any problem of selection that such a 

 vast number of seedling individuals are available, from which to choose 

 superior specimens, as is the case in the selection of specimens among 

 our walnut groves. 



Thoroughly testing out new seedlings for a period of years in any 

 quantity must, necessarily, be the work of a public institution. The cost 

 involved and the length of time necessary to make these determinations, 

 make it impracticable for individual fruit growers to make these tests. 

 The percentage of. medium varieties which are bound to dominate a 

 selection of a given number of seedlings has made the work rather 

 unattractive to the commercial nut grower. It is the purpose of the 

 Citrus Experiment Station to give whatever help is possible in this 

 endeavor. On the other hand, the growers of nuts can be of material 

 assistance in calling the attention of the Experiment Station staff to 

 seedling trees which are thought to be superior in one character or 

 another. 



Probably the most important characteristic to have in mind in the 

 preliminary selection of seedling trees is the ability of the tree to 

 resist the walnut blight. This one factor of disease is no doubt the 



