Isouron [3-(5-tert-butylisoxazol-3-yl)-1, 1-dimethylurea] was relatively easily leached from the soils in the laboratory experiments using three typical sugarcane soils in Taiwan. Leaching with 398mm of water at a rate of 8mm/hr in the soil columns removed 87.8, 69.2 and 52.2% of surface-applied isouron from Touliow sandy loam, Taichung loam and Annei silty loam, respectively. Under a model field condition, most of the herbicide remained in the upper 30cm of the soil after receiving 347mm of rainfall for 112 days. Adsorption of isouron by the soils may be expressed by the Freundlich and Langmuir equations. The K values of the Freundlich equation were from 0.58 to 2.91, and the maximum adsorption in Langmuir equation was 48.85 in the sandy loam, 72.15 in the loam and 94.43μg/g in the silty loam, respectively. The organic matter content and the kind of clay mineral in soil were important factors influencing the adsorption.

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A power duster of large maximum air volume (DMD11E) provides faster airflow in the blow head and at the blow holes. With its capacity, such as DMD11E contributes to improve distribution of o-sec-butylphenyl methylcarbamate (BPMC) deposits. High control of brown rice planthoppers was possible when insecticidal dusts were applied with such a DMD11E. Buprofezin having vapor action and high insecticidal activity could be applied with a DMD11E with a boom-type blow head. The relationship between the horizontal and vertical deposits of BPMC at the base of rice plant was improved by the use of a power duster of large air volume, and the slope of the regression line of less-drifting dust (DL) was about the same as that of regular dust (RD). Application with a shortened blow head, in contrast, resulted in extremely small deposits of BPMC and in inferior insect control at the end zone of the blow head. Deposition of BPMC in rice plants decreased at the heading stage, but increased at the yellow-ripe stage. The diameters of deposited dust particles of RD were mostly less than 10μm, while particles of 20 to 40μm diameter were predominant in DL. The amount of BPMC per 1mm² surface area of a particle deposited on a horizontal surface was 0.11μg/mm² in RD and 0.03μg/mm² in DL, and that on a vertical surface 0.20μg/mm² in RD and 0.05μg/mm² in DL. This may be the reason for high control of brown rice planthoppers by RD.

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Several 1-(2, 3-dimethyl-1-phenylpyrazol-5-on-4-yl) -3, 4-disubstituted-2-azetidinones have been synthesized by annulation of acid chloride on 2, 3-dimethyl-1-phenyl-4-(substituted benzylideneamine) pyrazol-5-one using Et₃N. All the compounds have been tested against two species of fungi. Based on screening data, some structure-activity relationship is given.

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The boundary layer theory was applied to a kinetic analysis of evaporation of a pesticide deposit on a flat glass surface in air current, and a rate equation, which is first-order to pesticide amount (m), was derived: -dm/dt=km, where rate constant (k) is expressed as a function of the absolute temperature (T), the mass-transfer coefficient (h_D), the molar mass (M), the pesticide vapor pressure (P) and the initial value of the amount (m₀) per area (A₀) of the deposit: k=h_D(A₀/m₀)MP/RT. Fenitrothion smeared on a flat glass plate in a circular thin layer 1.3cm in diameter was evaporated by changing wind velocity or the initial amount. Then, the fenitrothion residue was analyzed by gas chromatography at various time intervals, and the experimental rate constant (k_ex) was evaluated. In this case, the ratios of the theoretical rate constants (k_th) to the experimental rate constant ranged from 1.41 to 2.23. In another similar measurement of eight pesticides different in vapor pressure on the inside circular flat surface of glass stopper, the ratios were in the neighborhood of unity except for 0.41 and 2.56. The result demonstrates the proposed theoretical rate equation is a useful model for the evaporation of a pesticide deposit.

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Using approximately 50 different diphenyl ether compounds, the authors investigated the functional significance of the 3′ position known as ortho position in the phenyl ring carrying vitro, in relation to biological activity and chemical structure. When substituents at the 3′ position are expressed like [-X-Y-R], there was a good correlation between the Hammett constant σm or σ_p' which is the reactivity of atom X and atom Y, and biological activity. The correlation coefficient r was 0.85-0.86. Atomic bond population between atom X and atom Y of other diphenyl ether compounds were calculated by the, extended Hückel method, and the high correlation coefficient value (r=-0.911) was obtained as expected. These results showed the reactivity between atoms X and Y is closely related with the high herbicidal effect of dipheny ether compounds. In case of the group with an -OR moiety at the 3′ position, there was a good correlation between biological activities regardless of test conditions. That is to say, the herbicidal activity from the outdoor can be estimated by the herbicidal activity obtained from a pot test in the greenhouse. On the other hand, in case of the group with a -NHR moiety at the 3′ position, no correlation in biological activity was observed between tube and potted plant tests, though there was a good correlation in potted plant tests in the greenhouse and in a field. One of the reasons is that herbicidal activity depends on the physicochemical properties of the 3′ substituent. Namely, the binding energy of atoms X and Y in the 3′ substituent affects not only high herbicidal activity but also physicochemical properties, which are related to the practical use of a herbicide.

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Three species of paraquat (1, 1′-dimethyl-4, 4′-bipyridinium ion)-degrading microorganisms were isolated from a paddy field soil; an unidentified yeast (F-12), a Fusarium sp. (F-14), and a Penicillium sp. (F-16). In a liquid medium containing paraquat, F-12 required nutrient sources to eliminate paraquat from the medium while F-14 and F-16 did not. When F-14 and F-16 were incubated in a liquid medium containing methyl-¹⁴C-paraquat, both fungi accumulated paraquat in the cells, some portion of which was metabolized to monoquat (1-methyl-4, 4′-bipyridinium ion), monopyridone (1′, 2′-dihydro-1, 1′-dimethyl-2′-oxo-4, 4′-bipyridinium ion) (only in F-14), N-methyl isonicotinic acid, methylamine and ¹⁴CO₂.

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Histological effects of quizalofop, 2-[4-(6-chloro-2-quinoxalinyloxy) phenoxy] propionic acid, on root development and stem-base meristems in corn plants were studied. Elongation of the root was inhibited markedly by 0.1μM of the R(+)-isomer, but 10.0μM of the S(-)-isomer was required in order to produce the comparative inhibition. Quizalofop disrupted the mitotic process of the root tip. However, its effect was apparently secondary because the response to the inhibition of root elongation on the mitotic process was delayed about 10hr. Histological observation showed that damage started in the elongating zone of a root tip and spread to the meristematic zone. Histological effect of R(+)-quizalof op translocated into the stem-base region was characterized by severe damage in the primary thickening, intercalary and leafmarginal meristems, while there was little or no effect in the apical meristem. Differences in the histological effects of quizalofop might be due to the difference in translocation in the tissue and/or to the difference in sensitivity in the tissue to an increase in lipid metabolic turnover coincident with ACC activation because quizalofop dramatically inhibits ACC at very low dosage levels.

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Radiocarbon in 2, 4-dichlorophenyl 3′-methoxy-4′-nitro-[U-¹⁴C] phenyl ether (chlomethoxynil) orally administered to rats was rapidly and almost completely excreted into the urine and feces (13.7 and 79.5%, respectively) within 48hr. Major urinary metabolites were S-(3-methoxy-4-nitrophenyl) cysteine and S-(3-methoxy-4-nitrophenyl) mercapturic acid, accounting for 3.3 and 2.7% of dose, respectively. A trace amount of 3-methoxy-4-nitrophenyl sulfate was also detected in the urine. 2, 4-Dichlorophenyl 4′-acetamido-3′-hydroxyphenyl ether was the main fecal metabolite, which was newly identified in this study, accounting for 24.6% of dose. The finding that chlomethoxynil easily cleaved to S-(3-methoxy-4-nitrophenyl) glutathione and 2, 4-dichlorophenol in the presence of rat liver cytosol and glutathione suggested that the major urinary metabolites were formed through the mercapturic acid pathway from S-(3-methoxy-4-nitrophenyl) glutathione.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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A wide variety of toxicological study on bensultap have been conducted to assess its safety.
Bensultap is a relatively low toxic substance, and the toxicological signs of treated animals included ptosis, depression, hyperactivity, tremor, urine stains, soft feces, rough coat, lacrimation, salivation and convulsion in acute toxicity studies.
Bensultap technical might be a weak irritant but no-corrosive substance to the rabbit eye, and it caused no skin irritation. Bensultap technical might be a mild allergen, but its formulated product was not to be a sensitizing agent in guinea pig.
In chronic toxicity and oncogenicity studies, main toxicological findings related to the treatment of bensultap were including depression of body weight, decreased hematocrit and hemoglobin values, increased kidney weight and centrilobular hepatocellular swelling in the high dose groups. No treatment-related neoplastic lesions were observed in rats and mice.
The reproductive performance was not influenced with bensultap in rats, and no teratogenic potential was observed in rat and rabbit studies. Bensultap did not indicate a mutagenic potential in any assay.
Bensultap and its formulation were registered on April 14, 1986 in Japan.
The withhold standards for pesticide registration are listed below.
Rice 0.2ppm
Wheat and others 0.2ppm
Vegetables 3.0ppm
Tea 20.0ppm

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