exceed 1.2 p. p.m. and that the residues persisted for 12 weeks. Where 

 dieldrin emulsions were applied, rate of loss curves were obtained with a 

 rapid loss in the first 2 weeks, with residues remaining up to 16 weeks. 

 Fishgang and Shaw (6) applied 1 and 1-1/2 lb. of granular diazinon per acre to 

 alfalfa, birdsfoot trefoil, and ladino clover and reported that residues of 

 less than 0.01 p. p.m. were found 2 months later. In comparing the rate of 

 loss of azinphosmethyl from red and ladino clover, Shaw, Smith, and Fishgang 

 (26) reported the initial deposits were similar, but the rate of disappearance 

 from ladino clover was faster than from red clover. Hardee and others (14) 

 found the initial deposit of methyl parathion, methoxychlor, heptachlor, and 

 lindane was higher and the rate of loss was slower on timothy and alfalfa than 

 on birdsfoot trefoil and red clover. 



Due to the variability in analytical methods, the lower limit of sensi- 

 tivity as reported by the various authors differs considerably, particularly 

 in the case of the chlorinated hydrocarbon insecticides. The analytical 

 methods now available increase sensitivity approximately 100-fold over methods 

 previously available. 



This report presents the results of analyses made of red clover, lima 

 bean straw, and i*ange grass from 1957 through 1964 for residues of one car- 

 bamate, five chlorinated hydrocarbons, and eight organic phosphate materials. 

 Not all of these insecticides were applied to each crop during the 8-year 

 study. £'^ The data reported include the insecticides applied, rate per acre, 

 method of application, the analytical methods, and residues found at different 

 time intervals after application. 



FIELD PROCEDURES 



Red Clover 



The plots were generally 50 by 50 ft. in size. Residue samples of fresh 

 green clover varying from 2 to 9 lb. were taken by random sampling of 6 to 8 

 locations per plot. Approximately 4 sq. ft. per location were sampled. The 

 clover was stored in a refrigerator for a short time and then shipped with dry 

 ice by air express to the laboratory and kept frozen until analyzed. 



Lima Bean Straw 



Field plots ranged from 10 by 158 ft. to 20 by 100 ft. in size. One to 

 two pounds of diy straw was obtained from each plot at the time of threshing 

 the dry lima beans. The central 1/100 of an acre was threshed from each plot 

 and there were six replicates of each treatment. The diy straw was shipped by 

 air express and at the laboratory the samples were frozen until analyzed. 

 Granular insecticides were applied in the soil with and behind the seed at 

 planting. Twenty gallons of foliage spray per acre was applied with a power 

 sprayer using two nozzles per row at 125 pounds pressure. 



2/ Cooperating entomologists, Joseph Wilcox in California, Frank Cowan 

 and Fred Skoog in Montana, and H. W. Prescott in Oregon applied the insecti- 

 cides and did the field sampling. 



- 2 - 



