26 FARMEES' BULLETIN 933. 



whereas an active one will handle 250 pounds. It is very doubtful if 

 a slow-moving man should be employed to use a spray rod. The 

 pressure also depends upon the size of the hole in the disks. The 

 smaller the hole, the greater must be the pressure to furnish sufficient 

 spray material to wet the foliage without losing time. If a barrel 

 pump is used, from 80 to 100 pounds will be all that can be held with 

 one man pumping. From 100 to 125 pounds will be all that can be 

 maintained when the large lever pump is used with one man pump- 

 ing. For average conditions the power outfit should maintain from 

 175 to 250 pounds. When the pressure is less than 175 pounds op- 

 erations should cease. 



QUANTITY OF LIQUID REQUIRED TO WET TREES. 



Successful results can not be obtained unless sufficient material is 

 used to wet the foliage completely. To a certain degree the quantity 

 of liquid used is a good criterion of the efficiency of the spraying 

 done. We have known intelligent grove owners to use a gallon of 

 material for a tree 10 feet high. No satisfactory results can be ex- 

 pected from such spraying. The quantity to be used will depend 

 upon the density of the foliage as well as upon the size of the trees. 

 Small trees having dense foliage require much more material than 

 do larger trees with more sparse foliage and straggling branches. For 

 trees one or two years old one-half to three-fourths of a gallon is suf- 

 ficient. Trees 3 to 4 years old should require from 1 to 1J gallons, and 

 trees just beginning to bear should seldom receive less than 2 gallons 

 per tree. Trees of large spread and 10 feet in height sometimes re- 

 quire as much as 10 gallons, while the very largest trees require as 

 much as 15 gallons. The average tree of 10 to 12 feet requires about 

 8 gallons. 



RAINS AND DEWS. 



Spraying should never be done during a rain or when the foliage 

 is dripping wet. Spraying under such conditions dilutes the spray 

 to such an extent that it is entirely ineffective in killing the pests. 

 Operations should cease at least 10 minutes before a shower is about 

 to fall, in order to give the spray a chance to dry. After a shower 

 operations should be resumed in 20 to 30 minutes, or after a large 

 part of the drip has ceased. If heavy showers fall late in the after- 

 noon it is improbable that spraying resumed the same day will be 

 effective. It is seldom that the dew is so heavy as to prevent spray- 

 ing at 7 o'clock in the morning. 



THOROUGHNESS. 



In spraying for any pest on citrus trees the complete wetting of 

 every leaf on both surfaces as well as the branches and trunk should 



