THE SOAP TREATMENT. 75 



whole mixture should be boiled for at least one hour, either in an iron 

 kettle over a fire out of doors or in barrels by steam (see PL IX). 

 Prolonged boiling increases the percentage of the higher sulphides, 

 but the practical end is obtained with a boiling of the time indicated. 

 In the process of making, the color changes from yellow to the clear 

 brown of sulphide of lime, except for the excess of lime floating in it. 

 After an hour's boiling the full quantity of cold water can be added, 

 and the mixture should then be promptly applied in order to get its 

 full strength before the higher sulphides are lost by cooling and 

 crystallizing out. In transferring to the spray tank it should be 

 past thru an iron screen or strainer, and the tank itself should be pro- 

 vided with an effective agitator. 



Tlie wash is a winter application and can not be applied to trees in 

 leaf. It may be applied at any time after the falling of foliage in 

 early winter and prior to the swelling of the buds in sprmg. It will 

 probably be necessary also to make this application every year, or at 

 least as often as the San Jose scale develops in an}^ numbers. The 

 wash kills the San Jose scale not only by direct caustic action, but 

 apparently also by reason of the coating on the trees, which remains 

 in evidence until midsummer or later, and may kill or prevent the set- 

 tling of any young scale insects which may come from parents escaping 

 the winter action. 



Two applications may be given badly infested orchards — one in late 

 fall, the other in late spring. Where but one application is given, the 

 late spring just before the buds open is the best time. 



The wear on pumps and nozzles can be kept to a minimum by care- 

 fully washing the apparatus promptly after use. The Vermorel nozzle 

 is the best one for the wash, and additional caps ma}^ be secured to 

 replace worn ones. The use of an air or other gas pressure pump 

 instead of the ordinary liquid pump will save the wear of the lime on 

 the pump. In spra3dng with this wash clothing is ruined, and only 

 the oldest garments should be worn. Care should be taken also to 

 protect the eyes to avoid unnecessary inflammation. 



THE SOAP TREATMENT. 



Whale-oil or fish-oil soap, preferably made with potash lye, is dis- 

 solved in water by boiling at the rate of 2 pounds of soap to the gallon 

 of water. If applied hot and on a comparatively warm day in winter, 

 it can be easil}^ put on trees with an ordinar}^ spra}^ pump. On a very 

 cold day, or with a cold solution, the mixture will clog the pump, and 

 difficulty will be experienced in getting it on the trees. Trees should 

 be thoroly coated with this soap wash. Pear trees and apple trees 

 may be sprayed at an}^ time during the winter. Peach trees and plum 

 trees are best sprayed in the spring, shortlj^ before the buds swell. 



