Orchard Pests and their Control 369 



be given about thirty days later. Some of our progressive growers 

 are now relying on the first spraying, performed at just the right 

 time and applied in a thorough manner, and are meeting with 

 good success. 



Since we now know that trees may be poisoned by arsenic as 

 a result of spraying, it is very important that all persons should 

 spray as few times as possible and that the mixture should be as 

 weak as will do effective work. 



Advance has been made also in the amount of arsenic re- 

 quired. Formerly many growers thought that if a little was 

 good, much more would be better, and many used as much as 

 eight and ten pounds of poison to one hundred gallons of water. 

 Melander has recently found. that two pounds of poison to one 

 hundred gallons is sufficient to do effective work under Wash- 

 ington conditions. Consequently we think that three pounds to 

 each one hundred gallons is the most that should be recommended. 



Traps in the form of cloth bands around the trunks for catch- 

 ing the larvae are of considerable service if properly attended to. 

 But when one has learned to spray most effectively, it is no longer 

 worth while to use bands. Lights to trap the moths are value- 

 less. The doors and windows of cellars and storage houses should 

 be screened, as many moths develop from the worms in infested 

 fruit. 



Clean culture, and especially the stirring of the soil about the 

 trunks of the trees, will prevent the worms from successfully 

 undergoing their transformations under clods and about the 

 crowns. 



One should have outfits enough to complete the first spraying 

 within eight days from the time it is begun; or if one has varieties 

 that bloom at different times, arrange the work so that none of 

 the trees will have to wait more than one week from the time 

 the petals are off until they are sprayed. 



A good power outfit for spraying will do to take care of twenty 

 acres of apple orchard that is twelve or more years of age. It 

 will be a mistake to expect it to do much more than this. 



Large trees require from six to ten gallons of liquid each for 

 a thorough first spray. If the average is eight gallons and there 

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