The residues on potatoes of the sprout inhibitors propham (IPC) and chloropropham (CIPC) applied as a powder or by aerosol were studied. Sprout inhibitor residues were determined after 15 and 30 days of storage in peeled and unpeeled potatoes. In the powder treatment containing IPC plus CIPC, only residues of IPC were found. In the aerosol treatment containing only CIPC, both CIPC and IPC were determined. Peeling potatoes resulted in large decreases in sprout inhibitor levels in the aerosol treatment. Both aerosol and powder applied CIPC and IPC prevented sprouting for more than 3 months.
Experiments were carried out on three Italian farms to assess the degree of spatial variation of pesticide field concentration during treatment and during dissipation trials. Test pesticides were chloridazon and metamitron (both sugar‐beet herbicides) applied as a tank mix. The classical statistical technique and geostatistics were used to summarize and evaluate variable spatial data. The results show that the actual values of pesticide concentration for application rate and initial concentration in all three areas are lower than expected, thus indicating that under field conditions only a part of the pesticide reaches the soil during the distribution. The actual values for both herbicides in all three areas expressed as percentage of expected values ranged from 44·1% to 64·2% for application rate and from 40·5% to 99·5% for initial concentration. The coefficient of variation was similar for both pesticides and ranged from 23·8 to 74·1 for application rate, 24·1 and 58·8 for initial concentration and 11·1 and 110·0 for dissipation half‐lives. The high variability in application rate and initial concentration could be ascribed to an uneven herbicide distribution, and in dissipation studies to variation in half‐lives for the rate of herbicide loss from soil in different parts of the field. Geostatistic analysis indicated little spatial correlation, probably because the sampling sites were widely spaced on the field. In all cases, the data were not sufficient to estimate the range of influence, probably because of the size of the experimental fields and the sampling strategy. © 1997 SCI.
Diflufenican is a widely used highly effective residual herbicide used preemergence or early postemergence for the control of weeds in cereals. Diflufenican was applied at two sites presowing, each year for a four-year period. Soil samples were analyzed immediately following application, at 6 months and 12 months after application each year. In addition, at one of the sites in the last year, samples were taken over a more frequent time course to establish the pattern of decline. Each year a cereal (wheat) and maize crop were grown at the two sites as main crop and rotational crop, respectively. Analysis of the crop parts showed no residues in any of the wheat or maize plant parts in excess of 0.001 mg/kg, the limit of determination. Results of the analysis showed a consistent steady decline each year with no change (enhancement or decrease) in the rate. There was no accumulation from one year to the next, over the four-year period of the residual soil concentrations of diflufenican which were only slightly above 0.001 mg/kg the limit of determination. There was no evidence of movement of diflufenican below the surface layer in the soil. A DT50 value of ca. 14 days was calculated in the fourth year at one of the sites, followed by a more steady decline with a DT90 of 228 days. Keywords: Long-term degradation; residues; wheat; rotational crop; diflufenican
: Experiments were carried out on three Italian farms to assess the degree of spatial variation of pesticide Ðeld concentration during treatment and during dissipation trials. Test pesticides were chloridazon and metamitron (both sugar-beet herbicides) applied as a tank mix. The classical statistical technique and geostatistics were used to summarize and evaluate variable spatial data.The results show that the actual values of pesticide concentration for application rate and initial concentration in all three areas are lower than expected, thus indicating that under Ðeld conditions only a part of the pesticide reaches the soil during the distribution. The actual values for both herbicides in all three areas expressed as percentage of expected values ranged from 44É1% to 64É2% for application rate and from 40É5% to 99É5% for initial concentration. The coefficient of variation was similar for both pesticides and ranged from 23É8 to 74É1 for application rate, 24É1 and 58É8 for initial concentration and 11É1 and 110É0 for dissipation half-lives. The high variability in application rate and initial concentration could be ascribed to an uneven herbicide distribution, and in dissipation studies to variation in half-lives for the rate of herbicide loss from soil in di †erent parts of the Ðeld.Geostatistic analysis indicated little spatial correlation, probably because the sampling sites were widely spaced on the Ðeld. In all cases, the data were not sufficient to estimate the range of inÑuence, probably because of the size of the experimental Ðelds and the sampling strategy.
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