action. Other breakdown products remain in the soil and are toxic to both weeds and 
crop plants for a week or more after application. SMDC is registered on a non-residue 
basis for any crop if used at 490 lbs. per acre 7 days before planting on light soils, or 
14 days before planting on heavy soils. 
VC-13, a phosphorothioate compound, is reported to have a long residual action. 
This fact implies excellent stability in the soil. Residues have been found in various 
edible parts of crop plants by measuring the cholinesterase inhibition. The largest 
residues were found in root crops, much smaller ones in leaves, and only insignificant 
residues in true fruits (Boyd, 1959). VC-13 is registered for use on a non-residue basis; 
the application rate being 150 gallons of the 75 percent solution per acre prior to planting 
corn, cucumbers, peppers, squash, strawberries, or tomatoes. 
The application rate for DMTTis1/2tol1 lb. per 100 square feet. In the soil, it is re- 
ported to hydrolyze soon after application, Breakdown products are methyl isothiocyanate, 
formaldehyde, hydrogen sulfide, and monomethylamine, but it is believed that these 
degrade further (Torgeson, et al., 1957). DMTT is approved for use ona non-residue 
basis for treatment of soil for cabbage, peppers, and tomatoes at 275 lbs. per acre with 
an aeration period of 3 weeks. 
It is evident that the available information on the fate of nematocides in plants and 
soils is meager and incomplete. Research on this subject should start with determination 
of the breakdown products of nematocides in soil and their persistence under various 
conditions. The next step is a study of the uptake of the nematocides and their breakdown 
products by crop plants and the location of these in the edible or other parts of the 
plants. 
LITERATURE CITED 
Boyd, iGegks 1959. Determination of residues of 0,2,4-dichlorophenyl 0,0-diethyl 
phosphorothioate (VC-13 Nematocide) by cholinesterase inhibition. Jour, Agr. and 
Food Chem. 7:615-617. 
Brown, A. L., J. J. Jurinak, and P, E, Martin. 1958. Relation of soil properties to Br 
uptake by plants following soil fumigation with ethylenedibromide. Soil Sci, 86:136- 
139, 
Call, F., and N. G. Hague. 1957. Control of plant nematodes. Reports on the Progress 
of Appl. Chem. 42:605-612. 
O’Bannon, J. H. 1958. Application of emulsifiable dibromochloropropane in irrigation 
water as a preplanting soil treatment, U.S. Plant Dis. Rptr. 42:857-860. 
Shaw,E. 1948. The effectof a soil sterilant (dichloropropene-dichloro-propane mixture) 
on the chemical, physical and microbiological properties of desert soils, Doctor's 
thesis, University of Arizona. 118 pp. 
Stark, F, L. 1948. Investigations of chloropicrin as a soil fumigant. Cornell Univ. Agr. 
Exp. Sta. Memoir 278. 61 pp. 
Torgeson, D. C., D. M. Yoder, and J. B. Johnson, 1957. Biological activity of Mylone 
breakdown products, Phytopath. 47:536. (Abs.) 
Young, R. W., L.I. Miller, W. A. Hardison, and R. W. Engel. 1955. Bromide content of 
cows milk when fed forage grown on ethylene dibromide-treated soil, Dairy Sci. 
38:619. 
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