OBSCURE SCALE ON THE PECAN AND ITS CONTROL 17 



if the trees are in poor physical condition and a 5-percent emulsion 

 if the trees are in otherwise good physical condition. (3) Make all 

 applications during the strictly dormant period, but preferably not 

 until after the first of January, in order to give the trees plenty of time 

 in which to become dormant. (4) Apply the spray to all portions of 

 heavily infested small to moderate sized trees and to the lower three 

 fourths of all other trees, making sure that the application to the 

 parts sprayed is thorough, remembering that the scale specimens 

 must be hit by the spray to be killed by it, but do not drench the parts 

 sprayed beyond the point necessary to obtain a complete coverage. 

 (5) Use any oil within the range of the physical characteristics usually 

 recommended for use in dormant oil sprays. The usual oils appear to 

 be about equally effective and to offer about the same margin of 

 safety to the trees, with the added, though not yet thoroughly tested, 

 possibility that oils lower in viscosity and higher in volatility than 

 those generally recommended may prove effective at strong dilutions 

 and give a wider margin of safety to the trees. 



FORMULAS USED IN PREPARING LUBRICATING-OIL EMULSIONS 



The formulas used in preparing the lubrica ting-oil emulsions 

 employed in the tests reported upon in this circular are given below. 

 For more complete information regarding the preparation and use of 

 oil sprays, the reader is referred to Farmers' Bulletin 1676 (8). 



No. 1. — Lubricati?ig-oil emulsion (soap emulsifier) . Made according to the standard 



Government formula (1) 



Oil 2 gallons. 



Water 1 gallon. 



Potash-fish-oil soap 2 pounds. 



These materials are heated in a suitable container until the soap is 

 dissolved and the mixture comes to a boil. The mixture is then im- 

 mediately pumped twice with a bucket pump, or other suitable pump, 

 about 60 pounds' pressure being used. 



No. 2. — Lubricating-oil emulsion (soap emulsifier). Made according to the cold- 

 stirred rosin-fish-oil soap formula 8 



Oil 9 gallons (about 65 pounds) . 



Rosin-fish-oil soap 1 gallon (about 8 pounds). 



Pour the soap into a suitable container, then add a quantity of oil, 

 not more than one third of the volume of the soap. Stir the oil rapidly 

 into the soap until all the oil has disappeared and the mixture is some- 

 what stiff. Continue to add successive quantities of oil to the result- 

 ing mixture in an increasing quantity each time but never more than 

 one third of the total bulk of the mixture, and never adding oil until 

 that previously added has been thoroughly stirred into the soap. 

 Continue this procedure until all the oil has been stirred in. Any free 

 oil found on the surface of the stock emulsion can, and should, be 

 stirred into the mixture before it is used. 



SPECIFICATIONS OF OILS USED 



The specifications of the oils used in these experiments are given 

 in table 6. 



8 Siegler, E. H., and Brown, L. directions for making a cold-stirred lubricating-oil emulsion 

 using rosin-fish-oil soap as the emulsifier. U.S.Dept.Agr., Bur. Ent. Circ. E-277, 5 p., illus. 1930. 

 [Mimeographed.] 



