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TWENTY-NINTH FRUIT-GROWERS' CONVENTION. 



SPRAYING OPERATIONS IN THE PAJARO VALLEY. 



By prof, warren T. CLARKE, of Berkeley. 



The spraying experiments carried out by the University of California 

 Agricultural Experiment Station, working in co-operation with the 

 counties of Santa Cruz and Monterey, during the season of 1903, have 

 produced very interesting results and furnish a fund of data that will 

 be of great value in future operations against the codling-moth. It 

 seems quite pertinent to review briefly at this time the work done and 

 to indicate in a general way the results obtained and their application 

 to the problem of the economic control of this scourge of our apple and 

 pear orchards. 



The Scene of Operations. — The territory covered in these spraying 

 experiments extends from the Carmel Valley in Monterey County to 

 Boulder Creek in Santa Cruz County, a distance of some sixty-five 

 miles, and is in some places twenty miles in width. This extent of 

 territory afforded a great diversity of climatic conditions to be studied, 

 because of the different exposures and altitudes of the many apple 

 orchards therein. Some of the orchards on which our experiments 

 were made are not more than twenty feet above sea level, while others 

 were used that ranged up to near nine hundred feet altitude, and all 

 intermediate elevations were represented. The climatic conditions 

 encountered ranged from the rather cool, moist weather so character- 

 istic of the Pajaro Valley, to the warmer, drier conditions found in the 

 sheltered valleys of the Santa Cruz Mountains and in the hills of 

 northern Monterey County. In this territory, also, many different soil 

 conditions are found. The moist, rather heavy alluvial soils of the 

 main Pajaro Valley, the occasional adobes of this same valle}^, the 

 rather lighter gravelly loam of the mesas, the sandy and very light 

 sandy soils of some of the hill regions, on all of which apple orchards 

 are commercially grown, were represented in our experiments. These 

 various and diverse climatic and soil conditions are valuable in experi- 

 mental work of the character of this under discussion, because they 

 render that work and its results more general in their application in 

 the region studied than could otherwise be the case. The conditions 

 found in this region, however, are not generally the same throughout 

 the State, and therefore the recommendations based on the experience 

 here obtained might have to be modified to meet local conditions else- 

 where. The numbers and activity of the insect under consideration 

 vary quite materially in the different zones found in the region described, 

 due to climatic differences, and the vigor of the apple trees also varies 

 according to both soil and climatic conditions. 



These differing conditions suggest immediately the fact that spraying 



