510 ANNUAL, REPORTS OF DEPARTMENT OF AGRICULTURE. 



In addition to the benefits in increasing the yield by plowing and 

 spraying operations, in the case of prunes the treatment greatly in- 

 creases the value of the crop by preventing scabbiness of fruit, which 

 greatly reduces its market value. 



The operations in Contra Costa County were likewise notably suc- 

 cessful. Thus, in the case of Bartlett pears, 550 trees which received 

 two spray applications against the adults and a portion of the trees 

 receiving a third application against the larvae, all trees without ex- 

 ception came into full bloom, while the untreated adjacent trees 

 showed only a few scattered blossoms, and these were badly injured. 

 The yield of No. 1 fruit from the 550 sprayed trees was 1,700 boxes 

 and of No. 2 fruit 150 boxes, with a total value for the entire crop 

 of $1,435, or about $2.00 per tree. The unsprayed trees gave a yield 

 of less than one-fourth box per tree, the fruit being much scarred, 

 misshapen, and unmerchantable, and worth not over 12^ cents per 

 tree, thus showing a net benefit from spraying of $2,125 per tree, or 

 approximately $225 per acre. 



Spraying cherries in Sacramento County also gave satisfactory 

 results. Thus, the net value of fruit per tree in the sprayed blocks 

 was $8.09, as compared with the valuation of fruit from unsprayed 

 trees of $0,789 per tree. Deducting the cost of spraying, there is 

 shown a net gain per tree of $7.49 for spraying, or approximately 

 $889.80 per acre. 



Results of experiments and life-history studies of the thrips were 

 published in Circular 131 of the Bureau of Entomology, issued in 

 January, 1911, which was widely distributed to fruit growers in the 

 infested territory. This publication resulted in a notably increased 

 interest on the part of orchardists in the warfare against this pest. 

 A large number of fruit growers in the Santa Clara Valley and else- 

 where provided themselves with power and other spraying appa- 

 ratus, and a large amount of spraying was accomplished. 



In the bureau's field work in the spring of 1911 several orchards 

 were selected for settling additional points which had come up and 

 particularly for carrying out large-scale demonstration spraying. 



Agents of the bureau have endeavored to keep in close touch with 

 orchardists, giving them instructions in the preparation and use of 

 sprays, and it is believed that the growers for the most part are now 

 fairly familiar with the rather exacting conditions for successful 

 thrips spraying. 



The territory infested by the pear thrips from all available infor- 

 mation has apparently not materially increased during the past year. 

 Increased injuries, however, in the Courtland district have been the. 

 subject of considerable complaint by growers there located, and it is 

 planned to locate a man in that district during the spraying period 

 another spring. 



THE CODLING MOTH. 



Work on the codling moth, an important apple pest, has been con- 

 tinued largely along the lines followed during previous years. The 

 detailed life-history studies of the insect, in progress in different 

 fruit regions, are being satisfactorily accomplished, and it will be 

 possible, it is thought, to conclude these observations in the Michigan 

 fruit belt at the close of the present growing season. The studies 

 in Santa Clara Valley, Cal., are also nearing completion. The life- 



