8 



BULLETIN 821, XJ. S. DEPAKTMENT OF AGEICULTURE. 



In order to enable the observers to secure individual-tree performance 

 records from as many as 10 plats it was found necessary to arrange 

 the plats in such order that the smallest possible number of trees 

 would give rehable data of the comparative tree and fruit conditions 

 in the heated and nonheated orchards. Each plat included a block 

 10 trees long by 10 trees wide, or, roughly speaking, an acre of lemon 

 trees. On account of the great amount of work which would be 

 necessary in securing individual- tree performance records from all 

 the trees in the selected plats, it was found necessary to restrict the 

 actual detailed records to not more than 10 trees, and in some cases 

 to 5 trees, in each plat. The trees finally used for this study were 

 located by taking one of the trees at the center of the block and the 

 four trees at the corners. It was thought that by securing the records 

 of these trees and then by multiplying the figures obtained by the 

 factor 20 a fairly accurate line could be obtained on the production 

 of the plat on an acre basis. Where 10 trees were used in securing 

 the records two trees were taken in the center of the block and two on 

 each corner. In these plats the acre figures were secured by multi- 

 plying the total production of the 10 trees by the factor 10. 



After the performance-record trees were located they were care- 

 fully studied from the standpoint of strain characteristics, as it was 

 desirable that only typical trees of the best strain of the Lisbon and 

 Eureka varieties should be used for this study. 



Table II. 



-Description of the plats selected for the study of the effectiveness of orchard 

 heaters for frost protection. 



Plat. 



Variety. 



Treatment. 



Num- 

 ber, of 

 trees. 



Num- 

 ber of 

 pick- 

 ings. 



Picking period. 



Comparative 

 plats. 



No.l 



No. 2 



Lisbon 



. .do: 



Not heated 



} <■> 



Heated 



(2) 



Heated 



.do 



5 



\ 10 



5 



10 



10 



10 



10 



10 

 10 



8 

 6 

 6 



8 



S 



19 

 8 



11 

 8 

 3 



Feb. 14 to Dec. 12, 1913 



Feb. 15 to Nov. 17, 1913 



.. ..do 



4 

 3 



No. 3... . 



Eureka 



Lisbon 



Eureka — 



Lisbon 



2, 5, and 7 



No. 4 



Mar. 3 to Dec. 12, 1913 



1 



No. 5 



Mar. 4 to Dec. 12, 1913 



3 and 7 





/Mar. 6 to Dec. 8, 1913 



} 



3 and 5 



No. 6 



\Jan. 3 to Dec. 23, 1914 



No. 7 



Mar. 7 to Dec. 13, 1913 



No. 8 



No. 9 



Lisbon 



.do 



Not heated 



Heated 



Not heated — 



/Mar. 10 to Dec. 18, 1913 



\Jan. 31 to Dee. 30, 1914 



Mar. 12 to Dec. 12, 1913 



Mar. 14 to Dec. 1, 1913 



} 



10 



No. 10 



do 



9 











1 Plats 2 and 3 were partially protected by heaters in neighboring orchards. 



2 Inadequately heated; one heater for every four trees. 



The position of the plat was adjusted so that the trees finally used 

 were, with one exception, of the same strain in all the comparative 

 plats. The number of the plat, the variety of lemons, a statement 

 of whether the orchards were heated or nonheated, the number of 

 trees in each plat, the number of pickings made from the trees, the 

 periods during which the pickings wei-e made, and the number of 

 plats used for comparison are shown in Table II. A study of this 



