110 BULLETIISr 697^ U. S. DEPARTMENT OF AGRICULTURE. < 



fruiting they have all proved to be of the Marsh strain. In other • 

 words, an improved Marsh strain has been isolated and estabhshed ; 

 and brought into fruiting. The trees of this improved strain are ; 

 very uniform and their production is of the best grade and quality, j 

 Variation within the strain has been reduced through bud selection j 

 and from the commercial standpoint it has been eliminated. Doubt- ; 

 less further improvement in this strain can be effected through i 

 further bud selection in succeeding bud generations, and experiments ! 

 of this character are now under way. The most important step, ! 

 however, the establishment of a superior strain, has been effected. \ 

 Owing to a lack of opportunity, no attempt has yet been made to i 

 isolate an inferior strain, except in the case of the seedy strains. 

 A limited propagation of this commercially worthless strain has been I 

 made experimentally and has shown that it, too, can be isolated and \ 

 established by the selection of buds from trees persistently bearing ! 

 fruits of this character. There is every reason to believe that the j 

 other strains can be similarly established, and in an experimental 

 way this work is now being done. Such propagations are of no i 

 commercial value except that they further illustrate and demonstrate I 

 the im.portance of careful bud selection in the propagation of the j 

 variety. | 



Owing to the fact that the commercial grapefruit industry in Cali- ■ 

 fomia is stiE. in its infancy, the careful selection of buds from trees of i 

 the Marsh strain for all future propagations wiU likely result, through- i 

 out the State as a whole, in the development of trees of a uniform | 

 character and the production of crops of proved quality and value, ; 

 an achievement unequaled in the history of any other citrus variety j 

 now grown commercially. 



TOP- WORKING UNDESIRABLE TREES. 



Healthy trees of undesirable strains can be successfully top-worked j 

 and replaced by the valuable Marsh strain through the use of buds! 

 selected from trees of that strain. This operation has been success- '■ 

 fully performed on trees 12 years old. Doubtless older trees can be i 

 as successfully top-worked by the use of similar methods. I 



The selection of trees of the Seedy, Bell, and Rough strains for i 

 rebudding can usually be based on an inspection of the fruits. In ; 

 the case of trees of the Alternate-Bearing and the Unproductive \ 

 strains their selection should be based on performance records for 

 two or more seasons, preferably an even number. 



Two or more of the main limbs of the trees to be top-worked 

 should be used as foundations for the new trees. All branches 

 interfering with the work of budding should be cut away. The select 

 buds should be inserted in the limbs, two or more in each, about 12 

 inches from the trunk of the tree. After the buds have united with 



