BUD VAEIATIOlSr IN" THE MARSH GEAPEPRUIT. 9 



PLAN OF THE INVESTIGATIONS. 



The selection of groves of Marsh grapefruit in which to conduct 

 the work of these investigations was made by the senior writer in 

 1909, following a preliminary survey of the leading districts in which 

 the grapefruit was then grown in California, The conditions con- 

 sidered most desirable in the preliminary study of these groves 

 included (1) the successful and profitable production of fruit; (2) 

 uniformity of soil and cultural conditions in the groves; (3) protection 

 from tree injuries due to extreme climatic conditions, insect enemies, 

 and fungous diseases; (4) definite knowledge of the source of buds and 

 stocks from which the trees were grown; (5) plantings on virgin land; 

 (6) reasonable assurance of several years of uninterrupted observa- 

 tions under the same orchard management; (7) the use of little or no 

 manures or fertilizers and the absence of radi.cal tree or cultural 

 treatments; and (8) locations where the results of the investigations 

 would be of the most service and value to the industry. 



The performance-record plats finally selected for systematic obser- 

 vations were located in groves where the work of these investigations 

 could be carried on with the leas< possible danger of interruption and 

 where the conditions were as nearly as possible identical with those 

 mentioned above. The trees studied in these investigations have all 

 been grown on sweet-orange stocks, and the history of the buds used 

 in their propagation is known. 



In one performance-record plat, 25 trees were originally selected 

 in one block for individual-tree study, and later another tree was 

 added to this number. In the second performance-record plat, 52 

 trees in one block were originally selected for study, to which ntunber 

 26 select trees have been added during subsequent seasons. Indi- 

 vidual-tree records for six consecutive years have been obtained from 

 the 25 trees in the first plat and from the 52 trees in the other plat. 

 Most of the information presented in this bulletin was obtained from 

 a study of the performance records of these 77 trees first selected 

 for this work. 



As a result of the performance-record work discussed in this bulletin, 

 progeny tests of select trees and bud variations have been begun both 

 by top-working bearing trees and with nursery stocks. Some of the 

 results thus far obtained from these propagations will be discussed 

 briefly at this time, but the complete description of such work will be 

 left for publication in later reports. 



METHODS OF KEEPING PERFORMANCE RECORDS. 



The methods used in keeping the individual-tree performance 

 records are fully described in Farmers' Bulletin 794 of the United 

 States Department of Agriculture, entitled ''Citrus-Fruit Improve- 



