OBSCURE SCALE ON THE PECAN AND ITS CONTROL 19 



Miscible oils, 1 part stock solution to 15 parts water, proved 

 slightly less effective than 4-percent lubricating-oil emulsions. 

 Liquid lime-sulphur was ineffective at dilutions as strong as 1 part 

 stock solution to 5 parts water. 



Applications at any time (early, middle, or late) in the dormant 

 season of the tree were about equally effective. 



The method by which the several oils used were emulsified did not 

 appear to affect the degree of control produced by them. 



There were no appreciable differences in the degree of control 

 effected by the several oils used in the form of lubricating-oil emulsions 

 in the tests reported upon, indicating that any oil coming within the 

 limits of the specifications generally recommended for use in dormant 

 oil sprays should be satisfactory under most conditions. Limited 

 tests of oils somewhat lower in viscosity and higher in volatility than 

 those ordinarily recommended seemed to show them to be nearly as 

 effective as other oils and slightly less injurious to the trees. 



Applications of spray unusually early in the dormant period of the 

 tree and at the delayed-dormant period were more likely to result in 

 injury than strictly dormant applications. 



Any lack of vigor in the trees sprayed, or results of drought or 

 neglect, appeared to influence injury from the spray applications 

 more than any characteristic of the oil used in the spray. 



The spraying of pecan trees with oil sprays just before the crawlers 

 emerged did not result in any lasting deterrent effect on crawler 

 settling, and specimens that did settle on the oil-sprayed trees de- 

 veloped just as normally and successfully as those that settled on 

 unsprayed trees. 



Thorough application to all parts of heavily infested small to 

 moderate sized trees and to the lower three fourths of all other trees 

 during the strictly dormant period, but not before January, of 

 lubricating-oil emulsions at 4 or 5 percent oil content, according to 

 the physical condition of the trees, is the recommended control 

 measure. 



LITERATURE CITED 



(1) ACKERMAN, A. J. 



1923. PRELIMINARY REPORT ON CONTROL OF SAN JOSE SCALE WITH LUBRI- 



CATING-OIL emulsion. U.S. Dept. Agr. Circ. 263, 18 p., illus. 



(2) Comstock, J. H. 



1881. report of the entomologist. U.S. Dept. Agr. Ann. Rpt. Commr. 

 1880: 235-373, illus. 



(3) Dozier, H. L. 



1924. the obscure scale attacking pecan trees. Gulf Coast Grower 



2 (4): 2, 5, 7, illus. 



(4) Hammer, A. L. 



1926. brief summary report. . . Miss. Agr. Expt. Sta. Rpt. 39: 18-19. 



(5) Harned, R. W. 



1925. ANNUAL REPORT OF THE DEPARTMENT OF ZOOLOGY AND ENTOMOLOGY. 



Miss. Agr. Expt. Sta. Rpt. 38: 26-31. 



(6) Herrick, G. W., and Harned, R. W. 



1909. NOTES ON ADDITIONAL INSECTS ON CULTIVATED PECANS. Jour. EcOn. 



Ent. 2: 293-295. 



(7) Houser, J. S. 



1918. DESTRUCTIVE INSECTS AFFECTING OHIO SHADE AND FOREST TREES. 



Ohio Agr. Expt. Sta. Bull. 332, p. 165-487, illus. 



(8) Quaintance, A. L., Newcomer, E. J., and Porter, B. A. 



1931. lubricating-oil sprays for use on dormant fruit trees. U.S. 

 Dept. Agr. Farmers' Bui. 1676, 18 p., illus. 



(9) Woodard, J. S. 



1924. pecan insects. Tex. Dept. Agr. Bui. 77: 125-142, illus. 



