Synthesis and Activity of Novel Acaricidal/Insecticidal 2,4-Diphenyl-1,3-oxazolines
A series of substituted 2,4-diphenyl-1,3-oxazolines were synthesized and their acaricidal and insecticidal activities were examined. When either or both of the ortho-positions of the 2-phenyl group was substituted with halogen(s), an acaricidal activity against two-spotted spider mites (Tetranychus urticae) was observed as an effect on their eggs (ovicidal activity). Hydrophobic substituents at the para-position of the 4-phenyl group of 2-(2,6-difluorophenyl)-4-phenyl-1,3-oxazoline enhanced the acaricidal activity, and induced an insecticidal activity against green rice leafhoppers (Neophotettix cincticeps), diamondback moths (Plutella xylostella), and green peach aphids (Myzus persicae). When the 1,3-oxazoline ring was exchanged to either 1,3-oxazole or 4-methyl-1,3-oxazoline, both acaricidal and insecticidal activities were significantly decreased.
Key words: 2,4-diphenyl-1,3-oxazolines, acaricidal activity, two-spotted spider mites, Tetranychus urticae, etoxazole
Mechanism of the Phytotoxic Action of Herbicidal N-Isobutyl-N-(4-substituted benzyl)-4-halo-2-pentenamides
The N-isobutyl-N-(4-substituted benzyl)-4-halo-2-pentenamides show a potent light-dependent herbicidal activity against the barnyard grasses. The herbicidal mechanism was investigated with assay systems using cotton seedlings and an enzyme preparation from them as well as cultured unicelluar microalgae. Besides the protoporphyrinogen oxidase inhibition, some other mechanism(s) inhibiting step(s) involved in the chlorophyll biosynthetic pathway were suggested as the origin of the phytotoxicity.
Key words: light-dependent herbicidal activity, N-benzyl-N-isobutyl-4-halo-2-pentenamides, protoporphyrinogen oxidase inhibition, strucure-activity relationships.
Effects of Enantiomers of Inabenfide [4′-Chloro-2′-(α-hydroxybenzyl)isonicotinanilide] on Growth, Lodging and Yield Components of Rice (Oryza sativa)
We examined the growth regulating activities of enantiomers of inabenfide [4′-chloro-2′-(α-hydroxybenzyl)isonicotinanilide, 82211-24-3 (CAS RN Number)], an inhibitor of gibberellin biosynthesis, on rice plants (Oryza sativa L. cv. Koshihikari) with pot and field experiments. The (S)-form of inabenfide was more effective in reducing culm length than the racemate, whereas the (R)-form showed little effect. In treatment during the tillering stage, the (S)-form was about two times as potent as inabenfide (racemate) in its dwarfing effects on culms but also reduced the spikelet density to a greater extent than did the racemate. In addition, in treatments near the heading stage, the (S)-form (0.06 g/m2) reduced culm length, especially at the upper internodes, by 15% of the control and decreased the degree of lodging at maturity, whereas the racemate (0.24 g/m２) showed a lesser dwarfing effect. We conclude that: (1) the (S)-form is the active ingredient of inabenfide in reducing the culm length and lodging of rice plants.; (2) the (S)-form may be absorbed and translocated to elongating upper internodes more rapidly than inabenfide when applied near the heading stage.; and (3) treatment with the (S)-form near the heading stage will reduce the amount of ingredient required.
Key words: inabenfide, enantiomers of inabenfide, lodging, retardant, rice.
Soil Core Test, a Method of Pesticide Leaching Assessment for Upland Field
A vertical infiltration of pesticides in upland field was evaluated by a soil core method. Surface soil layer (0‐10 cm) was collected by a soil core collector (10 cm diameter, stainless steel) from an upland field treated with metalaxyl(Ridmil MZ●/WP), metolachlor (Dual●/EC) and bromacil(Hyper X●/WP). A steel cylinder loaded with vertically divided acrylic resin liner (5 cm inner diameter, 3 mm thickness) was guarded by stainless pipe (10 cm inner diameter, 10 cm height) and was driven to 50 cm under the surface. By this sampling method, the soil core from 10 cm to 50 cm layers was collected to be free from the contamination with pesticides in surface soil. The soil cores in acrylic resin liner collected from 6 spots in the field were divided in 10 cm soil layers, and mixed thoroughly for each layer. Soil water in each soil layer was separated by centrifugation at 11,000 rpm for 60 min at 4°C. The concentration of bromacil in soil water from 40‐50 cm soil layer was 0.114 mg/L at 105 days after the pesticide application, while metalaxyl and metolachlor were not detected in soil water below 30 cm depth. No leaching water of pan-lysimeter was collected from the depth of 50 cm-soil layer. The leaching water in porous-cup laid at the depth of 50 cm did not contain any pesticide.
Key words: soil core method, soil, soil water, leaching assessment.
Physiological Effects of Thiobencarb Stress in the Eel (Anguilla anguilla)
The effects of thiobencarb (0.22 mg/l) on the intermediary metabolism of the European eel, Anguilla anguilla, and its recovery from intoxication were evaluated. Physiological measurements were made in plasma, muscle and liver of the eels during exposure and after an 8-day recovery period in non-contaminated water. Hyperglycemia was detected during exposure, while liver and muscle glycogen levels decreased markedly. Blood lipid values increased, however, a decrease of the lipidic reserves was determined in liver tissue. Mobilization of proteins was detected specially in muscle tissue. Most of the metabolic disorders persisted after eight days in clean water. The observed effects of thiobencarb on intermediate metabolism are discussed in relation to a stress syndrome, as an indicative status of the physiological adaptability of the fish to compensate pesticide stress.
Key words: liver, plasma, muscle, eel, metabolism, thiobencarb, stress, recovery.
Herbicidal Activity and Characteristics of Pyraflufen-ethyl for Controlling Broad-leaved Weeds in Cereals
Pyraflufen-ethyl [ET-751, ethyl 2-chloro-5-(4-chloro-5-difluoromethoxy-1-methylpyrazol-3-yl)-4-fluorophenoxyacetate] is a potent Protox inhibiting herbicide which is also designated as a peroxidizing or photobleaching herbicide. In this paper, we demonstrated the herbicidal activity and characteristics of pyraflufen-ethyl as a cereal herbicide. Pyraflufen-ethyl showed excellent selectivity between cereal crops (wheat and barley) and a broad range of important broad-leaved weeds in post-emergence application. Its herbicidal activity was significantly higher than that of the existing cereal herbicides such as bifenox, ioxynil and mecoprop-p and comparable or even superior to carfentrazon-ethyl and metsulfuron-methyl, which are known as low use-rate herbicides. Pyraflufen-ethyl was also characterized by the fast herbicidal action and excellent activity against Galium aparine, one of the most troublesome broad-leaved weeds infested in winter cereal fields in West Europe. Field trials conducted in U.K. and France in 1990/1991 proved that pyraflufen-ethyl possessed high potentiality as a post-emergence cereal herbicide for controlling broad-leaved weeds selectively at rates of 6‐12 g a.i./ha.
Key words: Protox inhibiting herbicide, broad-leaved weeds control, pyraflufen-ethyl (ET-751), post-emergence cereal herbicide.
Mechanisms of Selective Action of a Protoporphyrinogen IX Oxidase-Inhibiting Herbicide Pyraflufen-ethyl between Wheat (Triticum aestivum) and Cleavers (Galium aparine)
To elucidate the mechanisms of selective herbicidal action of pyraflufen-ethyl [ethyl 2-chloro-5-(4-chloro-5-difluoromethoxy-1-methylpyrazol-3-yl)-4-fluorophenoxyacetate], the intrinsic activity on the target enzyme, foliar deposition and absorption, and metabolism of the compound were compared between wheat (Triticum aestivum L.) and cleavers (Galium aparine L.). Although protoporphyrinogen IX oxidase activities from wheat and cleavers chloroplasts were almost equally inhibited by pyraflufen-ethyl, a foliar application of the compound caused much more accumulation of protoporphyrin IX in cleavers than in wheat. The foliar deposition and absorption of the compound were much greater in cleavers than in wheat. Metabolic detoxification in wheat was much greater than that in cleavers. These differences in foliar deposition and absorption, and in the rate of metabolic detoxification would play an important role in the accumulation of protoporphyrin IX and the resulting selectivity of pyraflufen-ethyl between wheat and cleavers.
Key words: pyraflufen-ethyl, herbicide, protoporphyrinogen IX oxidase (Protox), mechanism of selective action, wheat, cleavers.
Synthesis and Herbicidal Activity of 1H-2,3-Benzoxazine Derivatives
A series of 1H-2,3-benzoxazine derivatives were synthesized and their herbicidal activity against upland weeds and selectivity against crops were assessed. Studies of the structure-activity relationship revealed that the strongest herbicidal activity was achieved when position-4 in the benzoxazine ring was substituted with a 3-chloro-4-fluorophenyl or a 3-bromo-4-fluorophenyl group. The treated weeds showed a strong bleaching symptom. Among the compounds examined, 4-(3-chloro-4-fluorophenyl)-1H-2,3-benzoxazine (23) and 4-(3-bromo-4-fluorophenyl)-6-fluoro-1H-2,3-benzoxazine (34), applied at 1.0 kg a.i./ha, showed strong pre-emergence herbicidal activity against upland weeds such as Echinochloa crus-galli and Digitaria ciliaris without affecting soybean.
Key words: benzoxazine, structure-activity relationship, pre-emergence herbicidal activity, upland weed.
Influence of Fenitrothion-Exposure on the Metabolic Activity of a Rotifer (Brachionus plicatilis) to Organophosphorus Insecticides
Key words: Brachionus plicatilis, organophosphorus insecticide, exposure, disappearance rate constant, bioconcentration factor, degradation ratio.
Chemical Identification of Fusicoccins from a Japanese Isolate Niigata 2 of Peach Fusicoccum Canker Fungus (Phomopsis amygdali) and Production of 3′-Deacetylfusicoccin A by the Fungus
Key words: peach Fusicoccum canker fungus, Phomopsis amygdali, 3′-deacetylfusicoccin A, fusicoccin fermentation.
Plant Growth-Regulating Activities of 4-Chloroindole-3-acetic Acid and Its Esters
Key words: 4-chloroindole-3-acetic acid, root formation-promoting activity, defoliation-inhibiting activity, freshness preservation activity.
Applications of Accelerator Mass Spectrometry (AMS) to Biochemical Studies
Key words: accelerator mass spectrometry, dermal exposure, radioimmunoassay, protein sequencing.
Useful Reactions for the Pesticide Synthesis: Esterification, Amidation, and Sulfonylation
Key words: esterification, amidation, sulfonylation.
Biodegradation Mechanisms of Pesticide Adjuvants Studied by Mass Spectrometry
Key words: biodegradation mechanisms, pesticide adjuvants, mass spectrometry, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), alkylphenol polyethoxylate (APEO), nonionic surfactant.
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