15 



other crops such work has been reported upon, but the writer feels that it is not 

 necessary here to quote them in order to demonstrate the importance of this 

 work. The isolation of valuable commercial strains arising as bud mutations of 

 established varieties in vegetatively propagated plants has been found to be prac- 

 ticable, and it seems likely that the work can be made increasingly useful when 

 once its importance is more generally understood. 



THE ELIMINATION OF UNDESIRABLE STRAINS. 



The undesirable strains in established commercial varieties arising from bud 

 mutations include those in which the plants produce unsatisfactory and unprofit- 

 able crops. For example, the Shade-tree strain of the Eureka lemon, (67) an 

 illustration of which is shown in Plate 27, which has been found by the writer 

 and his associates to constitute more than 25 per cent of the population in some 

 lemon orchards. The trees of this strain produce low yields of coarse thick-rind 

 fruits, lacking in juice. The culture of these trees has been found to be un- 

 profitable wherever investigated on account of their poor production. A number 

 of lemon orchards have been continuously unprofitable from this cause alone. 

 The elimination of the trees of the Shade-tree strain in established orchards 

 through top-working them with buds secured from productive trees of the de- 

 sirable Eureka lemon strain, an illustration of which is shown in Plate 28, has 

 resulted in the development of heavy-bearing trees and profitable orchards. 



In established orchards or plantations where individual trees or plants of 

 undesirable strains are discovered, such trees or plants can be successfully 

 eliminated by top-working with carefully-selected buds or grafts secured from 

 desirable parent trees, as shown in Plate 29, or by replanting with young trees or 

 plants of a desirable strain. In the propagation of young trees or plants the 

 elimination of the undesirable strains can be effected by using as parent trees or 

 plants only those individuals which are known not to transmit the undesirable 

 strain characteristics. 



The purity of commercial bud varieties can be maintained by eliminating or 

 avoiding the propagation of the undesirable strains which frequently originate 

 as bud mutations; examples of such mutations are shown in Plates 30, 31, and 32. 

 The improved varieties of plants are the most valuable and precious possession 

 of agriculture. Without selection most varieties are known to degenerate and 

 run out, largely due to the appearance of undesirable and unprofitable strains. 

 Therefore, the importance of purifying the proven and established varieties 

 through the elimination of undesirable strains must be obvious to every thinking 

 and unprejudiced person. 



THE AMELIORATION OF VARIETIES AND STRAINS THROUGH BUD SELECTION. 



The term amelioration of varieties and strains as here used may be defined 

 as the keeping up or the bringing up of the average performance of the indi- 

 viduals to that shown by the behavior of the best individuals in the variety or 

 strain through bud selection. The writer is of the opinion that from a com- 

 mercial standpoint this phase of plant improvement is the most important one of 



