52 Report of State Board of Horticulture. 



Knowledge of a multiplicity of sprays is not essential to 

 success in spraying. Equipped with an understanding of the 

 ränge 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 this 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 prevent 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 swal- 

 low plant tissues — usually caterpillars 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 insecticide. 

 Lime-sulphur is both an insecticide and a fungicide. Its ränge 

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

 cure-all. 



As intimated above, the three principal sprays in >ise in 

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

 sulphur Solutions. 



ARSENATE OF LEAD. 



Arsenate of lead is now the chief poison used in spraying for 

 the codling moth, although paris green is cheaper and gives 

 approximately as good results. Many brands of commercial 

 arsenate of lead are now to be had, and so far as our observa- 

 tions go all are reasonably pure. The various brands may, 

 however, be arranged into two defmite 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 that 

 the acid arsenates have some tendency to injure foliage and 

 that they cannot so well be used with the lime-sulphur Solu- 

 tions as can the neutral arsenates. While the available evi- 

 dence upon the above points is not sufficient to justify one 

 in condemning the acid arsenates, growers are advised to use 

 neutral arsenates wherever possible. 



Most manufacturers advise the use of three pounds of 

 arsenate of lead to 50 gallons of water. The Washington 



