78 MAINE AGRICUIvTURAI, e;xPERIME;NT STATION. I9II. 



gous injury the cause of which he does not know, the necessary- 

 information can be obtained by sending specimens to the sta- 

 tion. TimeHness means protection by prevention. 



Thoroughness of apphcation* is largely a matter of ex- 

 perience and until this is acquired the idea of thoroughness 

 will be that of the man who does the work. The amount nec- 

 essary for each tree will depend upon the density of the foliage 

 and the way it has been kept open by proper pruning. • 



Three important factors to be kept in mind in applying 

 sprays are the maintenance of a high pressure, the use of the 

 most efficient types of nozzles and the constant agitation of the 

 liquid. 



A pressure of less than 100 pounds is not likely to produce 

 the best results, and the insoluble nature of the insecticide in 

 the liquid makes constant agitation necessary to keep the arseni- 

 cal in suspension. 



With 100 pounds pressure and the improved type of nozzle 

 the proper spraying of a large tree is a matter of very short 

 time. The nozzle should deliver with considerable carrying 

 power a spray of fine mist in the form of a hollow cone. Under 

 these conditions it will be found necessary to keep the spray 

 rod constantly in motion in order not to drench any part of 

 the tree. 



Whether hand pumps or power machines are desirable de- 

 pends upon the size of the orchard and its location. Engine 

 power sprayers will be found most economical in large planta- 

 tions where their use is practicable. In small orchards, or in 

 large ones located on very steep, rough slopes, the hand pump 

 with its small spray tank may be best adapted. The greatest 

 disadvantage of the average barrel pump is the difficulty of 

 maintaining the high pressure necessary for good work, al- 

 though some of the improved hand machines may meet the 

 requirements. In large orchards the hand pump, unless at- 

 tached to a large spray tank, involves much loss of time due 

 to the necessity of repeated filling. 



* See Maine Station Bulletin 185, p. 391. 



