CIRCULAR No. 411 FEBRUARY 1937 



UNITED STATES DEPARTMENT OF AGRICULTURE 



WASHINGTON, D. C. 



A STUDY OF ARSENICAL DUSTING OF CABBAGE IN 

 RELATION TO POISON RESIDUES 



By Chas. E. Smith, associate entomologist, and W. J. Reid, Jr., P. K. Harrison, 

 and C. O. Bare, assistant entomologists, Division of Truck Crop and Garden 

 Insect Investigations, Bureau of Entomology and Plant Quarantine l 



The Bureau of Entomology and Plant Quarantine in Cooperation with 

 the Louisiana and South Carolina Agricultural Experiment Stations 



CONTENTS 



Page 



Introduction 1 



Methods 2 



Materials tested - 2 



Sampling and residue determinations 3 



Page 



Results 4 



Discussion. 5 



Summary and conclusions 7 



INTRODUCTION 



During the cabbage-growing seasons of 1932-33 and 1933-34 a 

 series of experiments was conducted at the field laboratories of the 

 Bureau of Entomology and Plant Quarantine at Charleston, S. C, 

 and Baton Rouge, La., to determine the relation of the number of 

 applications at specified rates and strengths of the arsenicals com- 

 monly applied on cabbage for the control of leaf-feeding insects and 

 the stage in the development of the crop when the applications are 

 discontinued, to the quantity of residue present at the time of harvest 

 on the portion of the plants usually marketed. 



Six experiments were conducted at each place, involving one 

 experiment for each of the six cabbage-growing seasons during the 

 3-year period. This provided an opportunity to study the influence 

 of varying climatic conditions, especially rainfall and temperature, 

 upon the quantity of poison residue remaining on the cabbage after 

 various intervals between the application of the insecticide and 

 harvest of the cabbage. Each experiment covered a series of plots 

 for each material and dilution used. In the majority of'the experi- 

 ments the plots were one- twentieth of an acre in area with rows 3 

 feet apart: the number of row^s per plot ranged from three to eight, 

 six rows being used in the majority of the experiments. 



1 Acknowledgments are due W. A. Thomas for general supervision of the Charleston studies and L. B. 

 Reed for his assistance. The analytical work in connection with the Charleston experiments was performed 

 by C. R. Gross of the Division of Insecticide Investigations of this Bureau. At Baton Rouge, the residue 

 determinations for one experiment were made by Sylvan B. Falck under the supervision of E. C Boudreaux 

 of the New Orleans office f the Food and Drug Administration of the U. S. Department of Agriculture. 

 The analyses for the remainder of the experiments were made by J. L. Farr and W. P. Denson, assistant 

 chemists, under the supervision of A. P. Kerr, chief chemist of the Louisiana Agricultural Experiment 

 Station. The writers gratefully acknowledge their indebtedness for these important contributions to the 

 work . 



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