18 The Bulletin. 



REMEDIES FOR THE OYSTER-SHELL SCALE 



Our Recommendation. 



1. Based on present knowledge and experience our first recommenda- 

 tion would be to use what are known as the "Soluble Oils" (oils so pre- 

 pared that they mix easily with water) at the strength of one gallon of 

 the oil mixed with eight or ten gallons of water, this to be applied as a 

 spray during late winter before the buds of the tree begin to open. The 

 names and addresses of several firms who manufacture these oils are 

 given on page 21. 



2. Should the grower not wish to use the soluble oils we would advise 

 spraying the trees with kerosene emulsion at a strength of 25 per cent 

 oil, making the application in late winter before the buds begin to open. 

 Formula and directions for use of kerosene emulsion are given on 

 page 22. 



3. If the grower does not desire to use either the commercial oils nor 

 the kerosene emulsion he may then depend on the usual lime sulphur 

 washes — either the commercial ones at a rate of one gallon to eight gal- 

 lons of water, or the home-made, fire-boiled wash prepared by the 

 formula of 15 pounds lime, 15 pounds sulphur, to 50 gallons water. 

 Barnes and addresses of firms who manufacture the ready-made wash 

 are given on page 22, and directions for preparing the home-made wash 

 ore given on page 23. But our tests and observations, both with the 

 Oyster-shell Scale and with others which are likewise protected with as 

 hard a scale as this, indicate that the oil washes are more penetrating 

 and more effective than the lime-sulphur preparations. 



4. If the infestation is discovered too late in winter to make the 

 treatments before the buds open, then we would advise that the trees be 

 sprayed during the last half of April or first half of May, using kero- 

 sene emulsion at strength of 15 per cent oil. This is based upon the 

 time of hatching of the e<rgs (already discussed) and the time recom- 

 mended is such as to reach the majority of the young before the scale 

 has become fully formed. 



5. In any case, no matter what remedy is used, it is best that any 

 dead, useless or superfluous branches be cut out, so that the spray will 

 more thoroughly reach what remains. Do the pruning before making 

 the application for Oyster-shell Scale. 



Test of Remedies. 



In order that the reader may understand the basis for the recom- 

 mendations given we give a brief account of some tests performed. 



During late winter and spring of 1912 Mr. Z. P. Metcalf, then Assist- 

 ant Entomologist in this office, conducted some spraying experiments 

 against the Oyster-shell Scale in the orchard of Mr. F. B. McCargo, 

 near Mount Airy, Surry County. The orchard was very generally and 

 very seriously infested. Tests wore made with several ready-made 

 preparations, as follows : 



