An analytical method has been developed for the determination of acetamiprid, (E)-N¹-[(6-chloro-3-pyridyl)methyl]-N²-cyano-N¹-methylacetamidine (ATP) and its metabolites, IM-2-1, IM-0, IC-0 and IM-0-Glucose in crops by gas chromatography (GC). ATP and its metabolites in crops were extracted with methanol and derivatized to methyl 6-chloronicotinate (IC-0-Me) through alkali hydrolysis, potassium permanganate oxidation and then esterification by diazomethane, followed by column chromatography clean-up and GC determination. The limit of detection was 0.01ppm and the recoveries of fortified samples ranged from 74 to 92%.

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The electronic configurations in ground and excited states of imidacloprid and related compounds were obtained by AM1 and ab-initio methods. The evaluated energy gap from the ground state to the singly excited state (S1) is in order of cyanoimine>nitroimine>nitromethylene, which is in accord with the actual photostability order among these compounds. Judging from that the HOMOs reside mostly in the guanidino or amidino part comprising the imidazolidine nitrogens and the LUMOs stretch toward the nitro and cyano groups, the primary excitations by UV absorption of these molecules is classified as the intramolecular donor-acceptor electron transfer. To this context more electron-donating thiazolidine exhibits a bathocromic shift from the imidazolidine compounds. The nitro group is coplanar with the guanidino or amidino part in the ground states. In the triplet excited state (T1) the nitro group becomes twist from the plane in the nitroamidine, on the other hand in the nitroimine the distortion is to such a small degree as the resonance stability can be still expected. The energy gap between HOMO and LUMO, and the bonding nature in the excited states are the determining factor for the photolytical behavior of chloronicotinyl molecules on field.

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When the controlled release granule of SSF-126, (E)-2-methoxyimino-N-methyl-2-(2-phenoxyphenyl)acetamide, was applied to a paddy field, the increases of SSF-126 concentration in the paddy water, paddy soil and rice plants were slower in the earlier stage and the decreases in the later stage were also slower, as compared with those of the non-controlled release granule which was made by extrusion and generally used in Japan. The concentration of SSF-126 became relatively higher on about the 10th day in paddy water, on the 40th day in water at 5cm deep in paddy soil, on the 72nd day in water at 10cm deep in paddy soil and on the 20-35th day in rice plants after application than those of non-controlled release one. These results suggested that the SSF-126 concentration in rice plants could be controlled by formulation, and gave a hint that the higher residual activity against rice blast could be obtained by using the controlled release granules of SSF-126.

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To evaluate the effect of the halogenated methyl groups of 1, 3, 5-triazines on nitrification by nitrifying bacteria, twenty-six halomethyl-1, 3, 5-triazines were examined. Nitrification inhibition activity by the 1, 3, 5-triazines was determined through two experiments; i. e. The inhibition activities were measured for ammonia-oxidation to nitrate (NO₃^--N) in an upland soil and in the second one, for ammonia-oxidation to nitrite (NO₂^--N) by Nitrosomonas europaea ATCC 25978. The 1, 3, 5-triazines bearing trichloromethyl group (s) inhibited nitrification more strongly both in soil and in cell suspension of ATCC 25978 than other partially chlorinated methyl-1, 3, 5-triazines. The 1, 3, 5-triazines having tribromomethyl group (s) exhibited rather weaker nitrification inhibition in soil, although they indicated the strong inhibition in cell suspension. The halomethyl-1, 3, 5-triazines in this study inhibited ammonia-oxidation step, but did not inhibit hydroxylamine-oxidation step in the culture of ATCC 25978. This fact was found that the inhibitory target site of them may be on the ammonia-oxidation step from ammonium (NH₄⁺-N) to hydroxylamine (NH₂OH), as we found for trichloromethyl-1, 3, 5-triazines in our previous study.

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Recently, we have found that 5-aminolevulinic acid (ALA) has plant growth regulating properties in lower concentrations besides herbicidal properties in higher concentrations. To clarify these properties, the influence of ALA under different application methods and their concentrations were examined using plant seedlings: rice, corn, kidney bean and radish. The results showed that the effects of ALA depended on the application method and their concentrations. The appropriate application of ALA increased the growth of seedlings to 110-150%, and the optimum concentrations were 0.1-1ppm on a root soaking, 30-100ppm on a foliar spray and 10-100g/10 a on a soil treatment, respectively. Although herbicidal properties at high concentrations has been reported to be different among plant species, the difference of the promotive effects of ALA at low concentrations between monocotyledon and dicotyledon was found to be negligible in this study. Moreover, ALA was also an easy biodegradable substance in soil.

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Carpropamid ({(1R*, 3S*)-2, 2-dichloro-N-[1-(4-chlorophenyl)ethyl]-1-ethyl-3-methylcyclo-propane-carboxamide}) was found to be an effective rice blast fungicide with systemic properties. The basic activities of the compound were studied in vitro and in vivo. The compound did not inhibit mycelial growth of various plant pathogenic fungi tested except Oomycetes spp. In addition, carpropamid did not show direct activity on the mycelial growth, the spore germination and the appressorium formation of rice blast fungus. Inhibition of fungal melanin biosynthesis was observed, however, in the mycelial growth test with many fungi and in appressorium cells of rice blast fungus. The compound showed strong penetration inhibition into rice epidermal cells at very low concentrations but was less effective once the appressorial penetration had started.

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When 4-allyl-2-azetidinone (B-143), without antifungal activity was applied to non-sterilized Kureha-soil (a commercial soil for gardening) artificially infested with Fusarium oxysporum f. sp. cucumerinum, occurrence of Fusarium wilt disease of cucumber (Cucumis sativus) was apparently reduced. However, when the soil was sterilized by autoclaving and infested with the pathogen, no effect of B-143 treatment was observed. These phenomena suggest that the disease suppression with B-143 may depend on the existence of some organisms in Kureha-soil. When Penicillium simplicissimum No. 8, isolated from the non-sterilized Kureha-soil, was re-introduced to sterilized Kureha-soil or some other kinds of soil, the effect of B-143 treatment was reproduced. The effect was also observed in the control of other Fusarium diseases such as tomato Fusarium wilt, cabbage yellowing, and stock Fusarium wilt. The results suggested that B-143 together with P. simplicissimum No. 8 generally exerted the reduction of soilborne Fusarium diseases.

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Two racemic diastereomers 5a and 5b, both of which are active ingredient of a seed treatment fungicide on rice, ipconazole, (1RS, 2SR, 5RS; 1RS, 2SR, 5SR)-2-(4-chlorobenzyl)-5-isopropyl-1-(1H-1, 2, 4-triazol-1-ylmethyl)cyclopentanol, and two other racemic diastereomers (1RS, 2RS, 5RS)-5c and (1RS, 2RS, 5SR)-5d were synthesized, and fungicidal activity and plant growth inhibitory activity were examined. Enantiomers of 5a and 5b were prepared, and their fungicidal activities were also examined. Racemic diastereomers 5a, 5b and 5d were more active than 5c in fungicidal activity (EC₅₀ value) in vitro on Gibberella fujikuroi, Cochliobolus miyabeanus and Pyricularia oryzae. In plant growth inhibitory activity test for seed treatment on rice, only 5d was slightly active in the first sheath growth inhibition. The comparative test of enantiomers in vitro revealed that the fungicidal activities of (-)-5a and (-)-5b were higher than those of corresponding (+)-5a and (+)-5b, respectively.

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[in Japanese]

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[in Japanese]

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