A 

 188 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 3 



of mapping out the problem and determining methods of approach. 



No single line of investigation was carried on long enough or thor- 

 oughly enough to warrant definite conclusions from this line of evi- 

 dence alone. The results of the different lines undertaken, however, 

 were in such close agreement with reference to the general principles 

 involved, that taken together the results were very significant and 

 seemed to warrant this preliminary publication. 



It might Jbe weft Ui nc^tsjn this connection that on account of the 

 seriourf and lajsting nature of the pear blight injury to the larger 

 portion of the pear orchards of the inter-mountain region, and the 

 impossibility of separating this injury from that of other causes, that 

 the investigation was confined to the problem as presented in the 

 apple orchards. 



A Study of Western Orchard Regions 



In the investigation of orchard regions a study was made of the 

 more typical orchard soils especially with reference to their alkali 

 content and general seepage conditions. Two or more of the oldest 

 and longest sprayed of the commercial orchards located in each of 

 the typical orchard regions were usually chosen and thoroughly inves- 

 tigated. On these orchards soil borings were made to ascertain depth 

 of soil and distance to ground water and for chemical analysis. Sam- 

 ples of surface soil were collected to study the deposition of arsenic 

 and samples of the trees taken to study its accumulation in the trees. 

 In each of the orchards, the number of sprayings applied and the 

 amount and kind of poison used were ascertained where possible. 

 These orchards were taken as representatives of the better orchard 

 conditions. In each valley at the same time, an attempt was made to 

 ascertain the places where the greatest losses of trees were taking 

 place and the conditions under which they occurred were investi- 

 gated. Owing to sickness, the chemical investigations of this part of 

 the work have not been completed and it is impossible at this time 

 to give the detailed statement of the chemical findings. 



It is hardly necessary to call attention to the fact that even under 

 the most favorable environment there is an occasional loss of a tree 

 through accident or individual weakness, and that even more fre- 

 quently trees are permanently injured, especially in the region of the 

 crown, through the ordinary processes of orchard cultivation. 



The Pajaro Valley in California is the principal apple shipping 

 section of that state. The soils are deep and range from loamy to 

 heavy adobe. No irrigation water is used and no indication of alkali 

 or of seepage conditions could be found in the principal orchard dis- 



