SELECTING MACHINERY AND EQUIPMENT 



307 



haulage does not change. Small trees require less material 

 and can be covered more quickly. However, more hauling 

 and walking are required, and the increase in number sprayed 

 is hardly proportionate to the decrease in their size. 



Small trees may, of course, be cared for with lighter and 

 less powerful equipment than is needed for large trees. 



(6) Consider the Length of Time within Which Applica' 

 tions Must Be Made and the Number Required, The grower 

 know^s from his study of insects and diseases the stages in their 

 life histories when they may be controlled. He knows that 

 he must perform his spraying operations at these times, and 

 that if he does not do so, the operations will result in failure. 



For instance, he knows that, whereas he may control peach 

 leaf curl by spraying at any time during the dormant season, 

 he must spray for aphis when the insect is present and in an 

 exposed situation on the buds. He must cover the orchard 

 rapidly in a rainy season for scab control. An outfit that might 

 be adequate to control peach leaf curl would not do at all for 

 some of the organisms that must be controlled within narrow 

 time limits during the growing season. 



AgaiU; one thorough application each year is sufficient for 

 peach leaf curl and usually for scale. Three or four applica- 

 tions may be required for codling moth in regions where there 

 are several broods each year, and an even larger number of 

 applications may be required for apple scab. These facts 

 influence the decision in selecting machinery. 



Further allowance must be made for windy or rainy weather 

 during the period when the organisms may be controlled. This 

 cuts down the available time and makes it necessary to in- 

 crease the capacity of the outfit. In most parts of the country, 

 except the Far West, not more than four days out of each 

 week are available for effective orchard applications. The 

 number is often less. 



(c) Consider Nature of the Ground over Which Work Must 

 Be Done. It is evident that level or rolling lands, free from 

 rocks, offer fewer obstacles to rapid work than rough or moun- 



