The persistence of azinphosmethyl on lima bean straw is illustrated by the 

 finding of 7„8 to 20.3 p. p.m. of azinphosmethyl on straw from green plants that 

 had been sprayed (foliage) with three treatments of 1,5 lb. of azinphosmethyl 

 per acre, the last treatment 44 days before harvest. 



Green lima be-ans treated with sprays (foliage) of 1/2 and 1 lb. of 

 dimethoate per acre carried no measurable residues in the harvested dried 

 straw, except 0.12 p. p.m. where 1 lb. per acre had been applied 37 days before 

 harvest. When two sprays (foliage) at this concentration were applied, the 

 last one 51 days before harvest, no measui^able residues were found. Based on 

 the above, it could be expected that if the 37-day time-interval had been 

 extended to 51 days no measurable residues would have been found. Soil treat- 

 ment 139 days before harvest with 0.5 and 1 lb. of dimethoate per acre did not 

 result in measurable residues in the dry lima bean straw. 



Soil treatment with 0.44 to 1.0 lb. of disulfoton granules per acre in a 

 granular formulation applied 132 to 139 days before harvest produced measurable 

 residues in the dry straw. Application of 0.36 lb. per acre did not result in 

 measurable residues. In all treatments, there were some samples found with no 

 measurable residues. In general the residue in the straw was approximately the 

 same for the three higher rates of application. 



Soil treatment with 0.5 and 1.3 lb. of phorate per acre, applied as gran- 

 ules, 139 days before harvest did not result in measurable residues of this 

 material in the dry straw. . , 



Two pounds per acre of trichlorfon applied as a spray (foliage) 44 days 

 before harvest resulted in residues of 0.02 to 0.07 p. p.m. on the dry straw. 



Range Grass 



The treatment of large areas of range land for the control of gi^sshoppers 

 is necessary in order to reduce the infestation and to preserve the range 

 forage. Major requisites for treatment of range grass include: (1) control of 

 the insects, (2) low cost per acre, and (3) persistence of the insecticide 

 during the period of control but not long enough to render the range unusable 

 for grazing purposes. Residues of Bomyl, carbaryl, diazinon, dimethoate, and 

 naled on range gi^ss are presented iji table 4. 



Bomyl was applied at the rates of 2 and 4 oz. per acre both as a water- 

 diluted emulsion and as an oil concentrate spray. The sprays were applied by 

 means of a modified turbine (Buffalo Turbine®) sprayer that permitted the 

 covering of fairly large acreages in a minimum of time. The original, or zero 

 day, deposits from the 2- and 4-oz. per acre water-emulsion spray and the 2-oz. 

 per acre oil concentrate spray were very similar, whereas the deposit from 

 the 4-oz. oil concentrate spray was approximately twice that of the others. 

 Fourteen days after application, this difference was no longer significant; and 

 after 28 days, the deposits remaining from the 4-oz. applications were 2.0 and 

 2.5 p. p.m. and that from the 2-oz. oil-concentrate was 1.6 p. p.m. 



Carbaryl at 4 oz. per acre was applied as a water-diluted emulsion spray 

 (foliage), both by modified (Buffalo Turbine) sprayer and aircraft. When 4 oz. 

 of carbaryl per acre was applied by turbine sprayer, the original deposit 

 (0-day s) ranged from 18 to 50 p. p.m. When the same rate was applied by 



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