188 HORTICULTURE FOR SCHOOLS 



Prunes are usually picked from the ground rather than 

 from the trees; for it has been found that they contain a 

 higher proportion of solids if allowed to remain on the tree 

 as long as possible. The drying process is then completed in 

 one of three ways : In Europe, the fruit is half baked in ovens 

 and drying is then finished in the open air. In California 

 this is usually done out-of-doors, in the sun. In the Pacific 

 Northwest, where the air is more humid, special buildings 

 erected for the purpose, called evaporators, are utilized. 

 Each method has some points in its favor. The European 

 system is said to impart to the fruit an especially desirable 

 flavor, but the product is unsightly, and therefore lacks the 

 marketing qualities of the American fruit. The sunshine 

 method of California is cheap, but cannot be as carefully 

 regulated during each stage of the process as can the evapo- 

 rator system. Early fall rains sometimes damage prunes 

 being dried in the sun. 



The prunes are dipped in a solution formed by dissolving 

 a pound of concentrated lye in about twenty gallons of water. 

 This is kept at the boiling point, and when the prunes are 

 dipped into it the lye causes the tough skin to become tender, 

 facilitating the escape of moisture from the fruit. The prunes 

 are then rinsed in clear water, and in some cases are allowed 

 to roll down an incline provided with many needle-like points 

 which pierce the skin and hasten further the process of drying. 

 The fruit is then placed on trays out-of-doors, or in the 

 evaporators, after which it is allowed to stand for several 

 days under conditions where escape of moisture will be much 

 less rapid. It is then "processed"; that is, dipped in boiling 

 water, or boiling water with glycerine added to it, or sub- 

 jected to a steam bath. This sterilizes the fruit, cleanses it, 

 and imparts a lustrous appearance. The product is then 

 ready to be packed and shipped. 



The curculio, plum gouger, aphis, and scales are among the 

 most common insects infesting plum orchards. Crown-gall 



