21 



citrus nursery for the study of problems in budding, stocks, and other phases 

 of propagation. It also furnishes to growers reliable information as to the 

 adaptation of citrus varieties to local soil and climatic conditions, accurate data 

 as to the production of the varieties and the relation of this production to market 

 conditions, and other information of value to the prospective planter or the 

 established grower. 



Potato growers in Maine, California, and in several other States have or- 

 ganized successful cooperative associations for the purpose of making available 

 commercially the results of bud selection work in potato varieties. 



Other associations of growers or propagators in industries founded upon 

 varieties of plants originated as mutations are in operation at this time. Amongst 

 these may be mentioned the Arizona-Egyptian Cotton Growers' Association, the 

 New England Tobacco Growers' Association, and the Nurserymen's Bud Selec- 

 tion Association of California. 



THE SELECTION OF SUPERIOR PARENT PLANTS. 



The selection of superior parent plants for propagation can be made on the 

 basis of individual plant performance record data and the intimate knowledge 

 of plant characteristics gained in the course of the plant performance record 

 work. 



In the citrus, the selection of superior parent trees is made after an ade- 

 quate number of performance records have been secured. Only the high-yielding 

 trees producing the best commercial fruits are considered as sources of bud-wood. 

 If the records or other observations show the production of any markedly off- 

 type fruits or striking variations, such trees are immediately discarded from fur- 

 ther consideration as sources of bud-wood for propogation. Only those high- 

 yielding trees which consistently produce uniformly good fruits are selected as 

 parent trees. 



PROGENY TESTS. 



The bud-wood from each parent citrus tree is kept separate. The buds from 

 each parent tree are used in separate blocks so identified in the nursery that 

 the progenies can be traced back to the individual parent trees. Examples of 

 the fine growth and early fruiting habits of such trees are shown in Plates 40 

 and 41. When the nursery trees are transplanted each progeny is kept separate, 

 and wherever possible the trees of each progeny are planted in the orchard so 

 that at any time the behavior of any progeny and its parent can be studied. In 

 this manner, as well as through additional experimental progeny tests now under 

 way, the transmitting power of the parent trees can be determined. In the 

 California citrus industry the foundation has been laid for the future selection 

 of parent trees on the basis of progeny records. It is probable that through this 

 work the most reliable sources of propagating material will be secured that has 

 ever been attained in any industry in the history of agriculture. In this con- 

 nection it may be stated that in addition to extensive cooperative commercial 

 progeny tests the writer and his associates are keeping investigational individual 



