

LIBRARY 



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APR 2 4 1967 



UNITED STATES DEPARTmlNT ^^ ^^^l^f^T^f^^^^i 

 Agricultural Researi^' ^igj^Ylicg BRANCH 



ARS 33-112 

 March 1967 



INSECTICIDE RESIDUES ON FORAGE CROPS 



By Donald A. George, Lillian I. Butler, Jay C. 

 Harold W. Rusk and Kenneth C. Walker 

 Entomology Research Division 



Maitlen 



The use of insecticides for the control of insects on forage and other 

 crops where a portion of the vine or top may be fed is a well-established 

 practice. The level of insecticide residues remaining in the crops is of 

 importance because of the possible deposition of the insecticide in the fat or 

 secretion in the milk of animals. 



Dobson, Thornberry and Belling (4)— reported the rapid rate of loss of 

 phorate residues on alfalfa. When analyzed by the cholinesterase inhibition 

 method, residues of approximately 400 parts per million declined in 14 days to 

 nonmeasurable levels. No adverse effects were observed in cattle that were 

 fed the treated hay. Huddleston and Gyrisco (15) found, when carbaryl in oil 

 was applied at 1 lb. per acre, there was a rapid loss of residue from alfalfa 

 and red clover. The original deposit of carbaryl on both crops was not as 

 high as was DDT applied at the same rate. Reynolds and coworkers (24) in 

 their work with trichlorfon on alfalfa found, when 1 lb. per acre was applied, 

 that the residue after 4 days was less than 1 p. p.m. and was not measurable at 

 10 days after application. 



A comprehensive survey of four chlorinated insecticides was done by mem- 

 bers of ENT-ARS-USDA (5) in 1956, 1957, and 1958 to determine the residue in 

 fat of cattle grazing on insecticide-treated range land (following standard 

 cattle management practices) . The residues on forage samples collected 1 day 

 after treatment were below 4 p. p.m.; in some of them, 0.4 p. p.m. remained 

 after 34 days. 



According to Dickason and Terriere (3) , early season application of 

 gi^nular aldrin and heptachlor at 1 lb. per acre to red clover did not result 

 in measurable residues at harvesttime when analyzed by a total chloride 

 method. When Gyrisco and Huddleston (13) applied aldrin, dieldrin and endrln 

 to alfalfa and measured the residues on fresh and cured hay, they found that 

 dieldrin was more persistent than endrin and endrin more persistent than 

 aldrin. 



In a study of dieldrin applied at dosages up to 1 lb. per acre in irri- 

 gated pastures Smith and others (27) , employing a colorimetric procedure, 

 found the initial deposit from granular applications of dieldrin did not 



1/ Underscored numbers in parentheses after the authors ' names refer to 

 Literature Cited at end of this report. 



