484 Important Orchard Pests and Spray Formulae. 



sume the surfaces of leaf or fruit. Of these arsenicals, arsenate 

 of lead is preferred at present because it adheres well and has 

 very slight burning qualities, even when used in excessive 

 amounts. Commercial brands should contain not less than 12% 

 per cent, of lead arsenate; some are stronger. With brands con- 

 taining 15 to 20 per cent, of lead arsenate, proportionately less 

 is required than is given throughout this bulletin in which the 

 amounts are based on a 12 1 /o per cent, paste. It is well to paste 

 the material with a small amount of water before diluting for 

 use. 



Arsenate of Lead. — Two pounds per 50 gallons or 5 pounds 

 per 50 gallons. The stronger formula is never required except 

 for the most resistant caterpillars, such as the gipsy moth. 



Paris Green. — One-third to Mj pound per 50 gallons. It 

 is commonly used with bordeaux. When applied with water, a 

 pound of stone lime should be added for each 50 gallons. (Paris 

 green should not be combined with lime-sulphur for summer 

 spraying.) In dry form paris green may be diluted at the rate of 

 1 pound with 10 to 50 pounds of land plaster, air-slaked lime or 

 flour. It may be sifted through a bag or applied with a bellows. 



Hellebore. — For a mild poison spray to be used in place of 

 arsenicals, particularly on currants and gooseberries, fresh helle- 

 bore is commonly used at the rate of 1 ounce per 2 to 3 gallons 

 of water. 



CONTACT INSECTICIDES 



117/ ale Oil Soap. — Whale oil or fish oil soap, when used at a 

 strength of 1% to 2 pounds per gallon of hot water, is a con- 

 venient remedy for scale insects, if applied during the late 

 winter. For summer use in the control of plant lice, pear psylla, 

 etc., the maximum strength is about V± pound per gallon of water, 

 and should be used at much less strength for tender foliage. 



Kerosene or Petroleum Emulsion. — One-half pound of hard 

 soap, 1 gallon of boiling soft water, 2 gallons of kerosene. The 

 soap is dissolved in the hoi water, the kerosene is added and all 

 churned vigorously through a pump for some minutes until emul- 

 sified. The emulsion is diluted for use from I to 15 times. 



Tobacco Water. — One-half pound of tobacco stems or leaves, 

 Steeped in a gallon of boiling water and later diluted with 5 to 10 



