Spraying Notes. 263 



would have been eradicated ; but it was desired to leave the trees 

 for study. 



While spraying for the San Jose scale in early spring has given 

 excellent results, there is no reason why late fall spraying should 

 not be equally effective, since the insect continues to multiply for 

 some time after the leaves have fallen. Furthermore, it is often 

 more convenient to spray in the fall than during the hurry of spring 

 work. Summer spraying is rarely advisable, since the foliage pre- 

 vents the insecticide from reaching all parts of the tree. We are 

 now experimenting with early winter spraying for the scale. 



Spraying vs. fiiinigating. — Most of the eastern fruit-growers 

 and nurserymen who have adopted the fumigation method of com- 

 bating the San Jose scale, report it efficient and practicable, when 

 properly done. Fumigation is certainly more thorough than spray- 

 ing. Hydrocyanic acid gas is very penetrating and can be depended 

 upon to kill all the scales or other insects on tlie tree in one thorough 

 fumigation, whereas several applications of the spray may be neces- 

 sary to accomplish the same result. In spraying there is always a 

 possibility that a few untouched insects may live and re-infest the 

 tree. Nevertheless, there is no doubt but that the San Jose scale 

 can be held in check by spraying. 



The comparative cost of the two methods is a practical point. In 

 spraying, a pump with a good kerosene attachment is the only 

 equipment necessary besides the usual spraying appliances. In fumi- 

 gation, tents are indispensable (if growing trees are treated) and are 

 generall}^ costly, especially those large enough to cover a full sized 

 orchard tree. The choice between spraying and fumigation will 

 therefor depend largely on the amount of work to be done and the 

 first cost of the tents. Nurserymen will find fumigation the most 

 effective and probably the most economical method of control, while 

 those with growing plants will find kerosene spray an efficient, 

 economical and simple method of checking the scale. 



The San Jose scale situation is improving, not because the scale is 

 less destructive but because it is better understood and methods of 

 combating it are more generally known. In some respects it is 

 undoubtedly the worst insect we have in the orchard. Every pre- 

 caution should be taken to guard against infection ; yet there is no 



