SPRAYS AND SPRAYING 



Prepared for this Report by Prof. A. B. Cordley, Entomologist of the 

 Oregon Experiment Station, pursuant to a resolution adopted by the Oregon 

 State Board of Horticulture, April 13, 1908. 



Knowledge of a multiplicity of sprays is not essential to success 

 in spraying. Equipped with an understanding of the range of 

 usefulness of three or four standard sprays, with a good spray 

 pump, and with a determination to do thorough work one is as well 

 fortified, as may be, against most orchard pests. Therefore this 

 article will be brief. In practically all of the orchard spraying 

 done in th's State but three kinds of spray are used, and probably 

 one of these may soon be largely dispensed with. To treat of more 

 is but to waste time and space and to lead to confusion. 



Most growers now understand that spraying is primarily to pre- 

 vent loss from insects and from fungous diseases, and that a spray 

 which is effective against one pest may be totally ineffective against 

 another. Still, for the benefit of the novice, it may be necessary 

 to emphasize the fact that there is no cure-all. Poisons like 

 arsenate of lead or paris green are used to destroy codling moth and 

 other insects which actually swallow plant tissues — usually cater- 

 pillars and beetles which feed upon leaves. They have little or no 

 value as fungicides and are not effective against San Jose Scale, plant 

 lice and other sucking insects. Bordeaux mixture is used to prevent 

 attacks of fungous diseases and has but little value as an insecti- 

 cide, liime-sulphur is both an insecticide and a fungicide. Its 

 ranofc of usefulness is therefore greatly increased, but it is not a 

 cure-all. 



As intimated above, the three principal sprays in use in this 

 State are arsenate of lead, Bordeaux mixture and lime-sulphur 

 so'iitions. 



ARSEXATK OF LEAD. 



Arsenate of lead is now the chief ])oison used in spraying for 

 the codling moth, although paris green is cheaper and gives approx- 

 imately as good results. Many brands of commercial arsenate of 

 lead are now to be had, and so far as our observations go all are 

 reasonably pure. The various brands mav, however, be arranged 

 into two definite groups which may be termed the acid arsenates 

 and the neutral or normal arsenates. While the evidence is not 

 conclusive, it appears to be true tliat (he acid arsenates have some 

 tendency to injure foliage and that they cannot so well be used 



