Pesticide Runoff and Mass Balance in Field Model Tests Analyzed by Commercially Available Immunoassay Kits
To understand pesticide runoff due to surface water flow from sloped cropland (6-6.5) with planted cabbages, runoff model tests with artificial rainfall were performed in different sized blocks of land. Immunochemical determinations using commercially available immunoassay kits were applied for pesticides in surface water. One hour after application of each 400 ppm emulsion of chlorothalonil (TPN) and diazinon, artificial rainfalls of 60 mm/hr for 10 and 23 min were induced to two small fields (blocks A and B: 6.3 m2 each) and the rainfall of 18.7 mm/hr for 30 min and the next day 25.2 mm/hr for 10 min were also induced to a large field (block C: 460m2). The ratios of runoff water recovered were 1.2% each in the blocks A and B, and 6.0% from the first rainfall and 5.8% from the second rainfall in the block C. The relative pesticide runoff was 0.14-0.62% for TPN and 0.06-0.39% for diazinon. When the results of analyses by both immunoassay and conventional GC were compared, they seemed to be roughly identical in similarly collected samples. Furthermore, deposits of pesticides on cabbages and soil surfaces were analyzed by immunoassay and the mass balance of each pesticide was estimated before and after rainfall in the test fields. TPN seemed to deposit better on cabbages and soil surfaces than did diazinon. Though in the block C almost half of the both pesticides initially deposited on the cabbages was washed off during the first rainfall, additional wash-off from the cabbages was observed only a little during the second rainfall. Before and after the second rainfall almost the same concentrations of each pesticide were found in the soil surface layer.
Key words: rainfall, surface flow water, pesticide runoff, mass balance, immunoassay, field model test.
Structure-Activity Relationships of the Azole Fungicide Metconazole and Its Related Azolylmethyl-cycloalkanols
Metconazole, (1RS, 5RS; 1RS, 5SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(lH-1, 2, 4-triazol-1-ylmethyl)cyclopentanol, is a novel triazole fungicide containing a cyclopentane ring. The related compounds, cyclopentanol, cyclohexanol and cycloheptanol derivatives having none or gem-dimethyl groups at the 2-position on the cycloalkane ring were synthesized, and their fungicidal activities were compared. The gem-dimethyl groups at the 2-position on the cyclohexane and cycloheptane rings were important for fungicidal activity as well as the case of the cyclopentanols. The cis-isomers of the cyclopentanols and the cycloheptanols showed higher fungicidal activities than the trans-isomers of them. On the contrary, the trans-isomers of the cyclohexanols were more active than the cis-isomers of them, but less active than the cis-isomers of the cyclopentanols and the cycloheptanols. Among the cis-cycloalkanols, the cyclopentanols and the cycloheptanols showed higher activities than the cyclohexanols. The conformational analysis of these cycloalkanols indicated that the relative three-dimensional orientation of the two important aromatic rings, triazole and benzene, of the cycloalkanols affected their fungicidal activities.
Key words: metconazole, cycloalkanols, azole fungicide, stereoisomerism, X-ray analysis, conformational search.
Efficacy of Acetamiprid 2% Granule against Green Peach Aphid on Cabbage by Various Soil Application Methods
The efficacy of acetamiprid 2% granule against the green peach aphid, Myzus persicae, on cabbage by various application methods was investigated. Planting hole, nursery box, row, over-all ridge and top dressing applications were tested as application methods. For the planting hole application, the efficacy of controlled- and uncontrolled-release formulations of acetamiprid was evaluated in two different soil type fields, Fujisawa and Kannami soil fields. Both granules of acetamiprid showed an excellent efficacy against the green peach aphid in Fujisawa and Kannami soil field at the dosage of I g/plant. The controlled-release granule of acetamiprid showed a high efficacy over 7 weeks after treatment in nursery box and planting hole applications at 0.5 g/plant. Row application at 3 kg/lOa and overall-ridge application at 6 kg/lO a also showed an outstanding efficacy against the insect over 5 weeks. The dosages of the insecticides in various application methods were designed to evaluate their efficacy against the diamondback moth, and it was confirmed that acetamiprid exhibited efficacy against the green peach aphid as well as against the diamondback moth. Moreover, it was also ascertained that uncontrolled- release granule possessed efficacy against the green peach aphid in top dressing application.
Key words: acetamiprid, granule, soil application, green peach aphid, cabbage.
Effects of Coating Conditions on Release Profiles of Controlled Release Granules Coated with Water Insoluble Polymer
We prepared capsule-type controlled release granules coated by water insoluble polymer, in which metominostrobin was used as a model agrochemical. In this study, the effects on release profiles of a) coating processes and b) content of polymer were evaluated at the equal amounts of the polymer. For coating, the release rate of metominostrobin from the granules coated with the polymer (solid content: 50%) by dropping process [D-1] was faster than that from the granules by fluidized bed process [F-l] . For the solid content, the order of release rate from the granules was F-1 > F-2 which was coated with the aqueous dispersion containing 5% solid content of the polymer by fluidized bed process. Superposition analysis on the release rates revealed that the difference in release mechanisms was dependent on the solid content of polymer but not on coating processes. Observation by SEM suggested that the release rate and release mechanism could correlate to each other and be related with the surface structure of the granules.
Key words: controlled release granule, coating condition, release profile, release mechanism, metominostrobin.
Soil Adsorption and Its Mechanism of the Fungicide Mepanipyrim
Soil adsorption of mepanipyrim labeled with 14C was investigated using a batch equilibrium method, and isotherms were calculated by the Freundlich equation for five different Japanese soils collected from the upland fields. The Freundlich equation described mepanipyrim adsorption adequately. Adsorption coefficients (Kf) ranged from 12.9 to 427, and normalized Kf based on the soil organic carbon content (Kf,oc) from 1090 to 5210. The values of l/n were smaller than unity for all soils tested. Desorption of mepanipyrim was hysteretic. Soil adsorption of mepanipyrim was pH dependent, showing the maximum adsorption at a pH value in the vicinity of its pKa 2.9. It is considered that the ionic bond between protonated mepanipyrim and the minus charge on soil colloid contributes to this pH effect. After decomposition of the soil organic matter with H2O2, Kf Values decreased for all soils tested. Adsorption of mepanipyrim on the H2O2 treated soils increased with the decreasing pH in the pH range above the pKa value.
Key words: pesticide, mepanipyrim, adsorption, soil pH.
Long-Term Control of Rice Blast Disease by Seedling Box Application of Controlled Release Granules Containing Metominostrobin
Key words: controlled release granule, rice blast disease, seedling box application, metominostrobin.
Adjuvant Helping Effects on Foliar Application of Cyhalofop Butyl
Key words: cyhalofop butyl, DEH-112, adjyuvant, foliar application, Echinochloa crus-galli.
The Blast Disease Fungi and Their
Metabolic Products
Manabu NUKINA
Key words: Magnaporthe grisea, Pyricularia oryzae, blast disease, fungal metabolite, phytotoxin.
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