Rhizome-induction activity of chiral 2-α-methylbenzylamino-4-alkylamino-6-chloro-1, 3, 5-triazines in Cyperus serotinus Rottb.

A cytokinin-like effect of chiral 2-α-methylbenzylamino-4-alkylamino-6-chloro-1,3,5-triazines was found using a rhizome-inducing assay with Cyperus serotinus Rottb. tubers. C. serotinus tubers germinated in distilled water yielded plantlets with roots and leaves. Secondary rhizomes were normally not observed within the regular 14-day incubation time in water culture, whereas after increasing incubation periods a very short rhizome appeared (controls). 6-Benzylaminopurine (BA) significantly stimulated rhizome induction, while other plant hormones were inactive. The (R)-isomers of the 1, 3, 5-triazine compounds also stimulated induction of the rhizomes, whereas the (S)-isomers did not. The described rhizome induction system seems to be suitable as a cytokinin bioassay. The (R)-1, 3, 5-triazine compounds showing rhizome-inducing activity (RI activity) inhibited root formation and plant growth at high concentrations with symptoms which were very similar to those of BA. Therefore, the (R)-isomers appear to act as cytokinins in the rhizome induction assay.     

The effect of atrazine,cyanazine and cyprazine on photosynthesis and growth of nine grasses*

A semi-open circuit system for measuring changes in net CO₂ exchange (NCE) in single leaves of intact grasses following herbicide treatment is described and evaluated. There were significant differences in levels of inhibition and subsequent recovery of NCE in maize and eight weedy panicoid grasses following limited root uptake of atrazine (2-chloro-4-ethyl-amino-6-isopropylamino-1,3,5-triazine). cyanazine [2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine] and cyprazine (2-chloro-4-cyclopropylamino-6-isopropyl-amino-1,3.5-triazine). Rate of NCE recovery was positively correlated (P = 0.05) with growth of seedlings in nutrient solution containing the herbicides. Rates of NCE recovery >0.9 mg CO2 per dm2 per h/h reflected rapid rates of herbicide detoxification in the leaves and a significant tolerance to preplant incorporated and postemergence applications of atra-zine, cyanazine and cyprazine. In contrast, some species, e.g. large crabgrass [Digitaria sanguinalis (L.) Scop.] and proso millet (Panicum miliaceum L.) treated with cyanazine demonstrated considerable tolerance to these treatments in spite of low NCE recovery rates indicating that factors other than foliar detoxification may play an important role in the tolerance of some grasses to 2-chloro- 1,3,5-triazine herbicides.     

The analysis of crops and soils for the triazine herbicide cyanazine and some of its degradation products. I. Development of method

Radiochemical techniques have been used to develop efficient procedures for the extraction of residues of cyanazine herbicide [‘BLADEX’,

1 BLADEX and FORTROL are Shell registered Trade Marks.

^a ‘FORTROL’,^a 2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine] and its metabolites 2-chloro-4-(1-carbamoyl-1-methylethylamino)-6-ethylamino-1,3,5-triazine ( II ), 2-chloro-4-(1-cyano-1-methylethylamino)-6-amino-1,3,5-triazine ( V ) and 2-chloro-4-(1-carbamoyl-1-methylethylamino)-6-amino-1,3,5-triazine ( VI ) from crops and soils. Partition and column chromatographic techniques have been established for the purification of the extracts. The full analytical procedure is described and the final determination of all four compounds is by g.l.c. with electron capture detection with blank values for field samples generally 0.02 part/million and with good recoveries.     

The analysis of crops and soils for the triazine herbicide cyanazine and some of its degradation products. II. Results

Crops and soils from field trials in 1967–1970 in several countries have been analysed for residues of the triazine herbicide cyanazine (‘BLADEX’

1 Shell Registered Trade Mark.

^a or ‘FORTROL’^a' 2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine) and for its degradation products 2-chloro-4-(1-carbarmoyl-1-methylethylamino)-6-ethylamino-1,3,5-triazine ( II ), 2-chloro-4-(1-cyano-1-methylethylamino)-6-amino-1,3,5-triazine ( V ) and 2-chloro-4-(1-carbonyl-1-methylethylamino)-6-amino-1,3,5-triazine ( VI ). The time for the concentration of cyanazine in soils to fall to half the initial value was in the range 1.3 to 5 weeks with a mean value of 2.4 weeks. The rate of loss was not affected by sparse crop cover and there was some indication that the rate was greater under moist soil conditions. Residues of up to 0.5 part/million of ( II ) and up to 0.08 part/million of ( VI ) were detected in soils at 4 weeks from cyanazine application at 2 kg/ha. The residues of cyanazine and the degradation products declined rapidly and were 0.07 part/million or less at 16 weeks from treatment. Repeated annual applications did not lead to a detectable build up of residues in soil. Neither residues of cyanazine nor those of ( II ), ( V ) or ( VI ) could be detected in a wide range of crops harvested from soil treated in accordance with the likely recommendations and the limits of detectability were 0.01 to 0.04 part/million.     

Potassium uptake in atrazine-treated roots of sensitive and resistan plants

The action of atrazine and its biodegradation products on the membrane transport of potassium in roots was evaluated in both sensitive and resistant plants. Excised roots of maize and oat showed inhibition of potassium uptake efficiency in the presence of 1.4 × 10^?4M atrazine and 1.4 × 10^?4M deethylated atrazine. Other biodegradation products such as 2-chloro-4-amino-6-ethylamino-1,3,5-triazine,2-chloro-4,6-,bisamino-1,3,5-triazine, and 2-chloro-4-amino-1,3,5-triazine showed no inhibitory effect on the K⁺ uptake capacity. Two maize hybrids showing different uptake efficiency were inhibited differently by atrazine. We suggest that atrazine and deethylated atrazine inhibited the K⁺ transport interacting directly with the plant cell membranes without discerning between resistant and sensitive plants.     

Novel 1,3,5-triazine derivatives with herbicidal activity

New fluoroalkyl-substituted 1,3,5-triazine derivatives were synthesized and screened for herbicidal activity using a greenhouse pot test. Surprisingly, a series of 2-alkyl-4-fluoroalkyl-6-aralkylamino-1,3,5-triazines e.g. 6-(4-bromobenzylamino)-2-methyl-4-trifluoromethyl-1,3,5-triazine was found to possess strong pre- and post-emergence herbicidal activities, although the conventional herbicidal 1,3,5-triazines generally should have a 2-substituted-4,6-diamino-1,3,5-triazine structure for herbicidal activity. Our compounds show strong Photosynthetic Electron Transport inhibitory activity (PI₅₀ c 7). Although their herbicidal effect is considered to be caused by a process similar to that for the conventional 1,3,5-triazine herbicide atrazine, they can control atrazine-resistant Chenopodium album effectively, and will thus form promising trial compounds for new triazine herbicide design.     

2-anilino-3-methylbutyrates and 2-(isoindolin-2-yl)-3-methylbutyrates,two novel groups of synthetic pyrethroid esters not containing a cyclopropane ring

A new series of substituted 2-anilino-3-methylbutyrates has been prepared; bioassay data for these compounds on Heliothis virescens, Musca domestica, Aphis fabae and Tetranychus urticae are presented and discussed. Some unexpected relationships were observed between the nature of the substituents and the biological activity. Increases in foliar stability were noted with certain substitution patterns. Both α-cyano-3-phenoxybenzyl 3-methyl-2-(α, α, α,2-tetrafluoro-p-toluidino)butyrate and the corresponding 2-(2-chloro-α, α, α-trifluoro-p-toluidino)-3-methylbutyrate showed good stability in air and light, and exhibited biological activities of a similar nature and potency to those of previously known synthetic pyrethroids. Esters of the (R)-2- anilino-3-methylbutyric acids are far more active than those prepared from the (S)-enantiomers. The (R)-configuration at C-2 in these acids is sterically equivalent to the active absolute configuration at the chiral carbon α to the carboxylate group in both the permethrin and the fenvalerate types of pyrethroids. A new class of insecticidal 2-(isoindolin-2-yl)alkanoates is also reported. In this series the most biologically active analogue was α-cyano-3-phenoxybenzyl 3-methyl-2-(4,5,6,7-tetrafluoroisoindolin-2-yl)butyrate. These esters were considerably less stable than the anilino analogues on exposure to air and light.     

The disappearance and movement of three triazine herhicides and several of their degradation products in soil under field conditions

Several degradation products of the iriazine herbicides atrazine [2-chloro-4-ethylamino-6-isapropylainino-1,3,5-triazine], cyprazine [2-chloro-4-cyclopropylamino-6-isopropylamino-1,3,5-triazine] and cyanazine [2-chloro-4-(l-cyanomethylethyl-amimo)-6-ethylamino-1,3,5-triazine] were monitored over a 3-year period in soil Trom fields under maiTC production. The soils were predominately loamy sands and sandy clay loams. HydroKy-triazines were determined semi-quanlilatively m the soil samples by gaschromalography, after methylation. Their levels ranged Trom 0.05 to 0.5 ppm. The hydroxy-triazines were the predominant triazine residues in the field during ihe spring and autumn, N-de-ethylated atrazine [2-chloro-4-amino-6-iso-propylamino-1,3,5-triazine] persisted at relatively high levels (0.015–0.02 ppm) 12 months after the application of atrazine. Greater proportions of N-de-ethylated atrazine and cyanazine II [2-chloro-4-(1-carbamoyl-1-methyleihylamino)-6-ethyl-amino-s-iriazine] than of atrazine or cyanazine were found to move through the soil profile into subsurface drainage water (1.2–1.6 m depth). Abbau und Transport von drei Triazin-Herbiziden und einiger ihrer Abbauproduk te im Boden unter Feldhedingungen Boden von Maisfeldern wurde über eine Periode von drei Jahren auf Abbauprodukte folgender Triazin-Herbizide unter-suchi: Atrazin [2-Chlor-4-äthylamino-6-isopropylatnino-1,3,5-triazin], Cyprazin [2-Chlor-4-cyclopropylamino-6-isopropyla-mino-1,3,5-(triazin) und Cyanazin [2-Chlor-4-(1-cyanoinethy-läthylamino)-6-äthylamino-1,3,5-triazin], Bei den Böden han-delie es sich hauptsächlich um lehmige Sande und sandig-tonige Lehme Hydroxy-Triazine wurden in den Bodenproben gas-chromatogruphish nach Methylierung. semi-quantitativ be-stimmt. Ihre Konzeniration im Boden betrug zwischen 0.05 und 0.5 ppm. Die Hydroxy-Triazine waren im Frähjahr und Herbst die vorherrschenden Rücksiände, N-desäthylieries Airazin [2-Chlor-4-amino-6-isopropyIamino-1,1,5-triazin] war zwölf Monate nach der Atrazin-Applikation mit relative hohen Kon-zenirationen(0.015–0.02 ppm) vorhanden. Von N-desäthylier-tem Airazin und Cyanazin II [2-Chlor-4-(1 carbamoyl-1–methy-läthylamino)-6-äthylamino-s-triazin] wurden grössere Anteile im Boden in das unterirdische Drainagewasser transportiert (1.2–1.6 m Tiefe) als es für Atrazin oder Cyanazin der Fs Swiir Disparition et migration dans le sol, au champ, de trois triazines herhicides et de plusieurs de leurs produits de dégradalion. Plusieurs produits de dégradation des triazines herbicides suivantes: atrazine (2-chloro-4-éthylamino-6-isopropylamino-1,3,5-triazine) cyprazine (2chloro-4-cyclopropylamino-6-isopropylamino-l,3,5-triazine) et cyanazine (2-chloro-4 (l-cyanométhyléthylamino)-6-éthylamino-l,3,5-triazine) ont été contrölés dans le sol. pendant une période de trois années, dans des champs de maïs en production, Les sols étaient pour la plupart sablo-limoneux et limono-argilo-sableux, Les hydroxy-triazines ont été déterminées semi-quantalivcmeni dans les échantillons de sols, par chroma tographie gazeuse aprés méthy lation, Leursconcen [rations s'étendaienlde0.05à 0.5ppm, Les hydroxy-triazines ont été les résidus les plus imporiants dans le champ au printemps et à I'aulomne, L'alrazine N-dé-éthylée [2-chloro-4-amino-6-isopropylamino-l.3.5-triazine] a persistéà des concentralions rclativemeni élevées (0.015 à 0.02 ppm) douzemois aprés l'application de l'atrazine, Il a été conslaté que des proportions d'atrazine N-dé-éthylée et de cyanazine II [2-ehloro-4(l-carbamoyl-1-méthyléthylamino)-6-éthylamino-1,3,5-triazine] plus importantes que celles de l'atrazine ou de la cyanazine, migraient à travers le profil du sol. dans la subsurface de drainage dc l'eau (1,2 à 1.6 m de profondeur).     

The breakdown of the triazine herbicide cyanazine in wheat and potatoes grown under indoor conditions in treated soils

The breakdown of the triazine herbicide cyanazine (“BLADEX”,^a 2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine) has been studied in spring and winter wheat and potatoes grown under indoor conditions in soils treated at planting with up to 1.5 kg/ha of the radiolabelled herbicide. Breakdown products were mainly those formed by hydrolysis of the cyano group to give an amide ( II ) and an acid ( III ) followed by hydrolysis of the chlorine to hydroxyl ( IV ). De-N-alkylation reactions also occurred although these were less evident in soils. In wheat the chloro acid ( VII ) formed by the des-ethylation of ( III ) was more evident than in previous studies with maize. In all of the crops at harvest the residues were mainly of the hydroxy acids ( IV ) and ( VIII ); ( IV ) 2-hydroxy-4-(1-carboxy-1-methylethylamino)-6-ethyl-amino-1,3,5-triazine; ( VIII ) 2-hydroxy-4-(1-carboxy-1-methylethylamino)-6-amino-1,3,5-triazine, respectively. In potatoes and spring wheat they were present in both free and conjugated forms whereas in winter wheat they were almost entirely in conjugated forms. The compounds (IV) and (VIII) are of a low order of toxicity to animals and are not herbicidal. They are unlikely to present a residue hazard if present in field crops.     

Effects of various classes of herbicides on four species of algae

Chlorella pyrenoidosa, Chlorococcum sp., Lyngbya sp., and Anabaena variabilis were cultured in Bold's basal medium. They were treated with 0.1, 1.0, and 10 μM concentrations of 2-chloro-2′, 6′-diethyl-N-(methoxymethyl)acetanilide (alachlor), 2-chloro-4-(ethylamino)-6-(tert-butyl-amino)-s-triazine (terbuthylazine), 2-sec-butyl-4,6-dinitrophenol (dinoseb), 1,1-dimethyl-3-(α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine) (profluralin), 2, 4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne), and (2,4-dichlorophenoxy)acetic acid (2,4-D). Growth of all algal species tested was markedly reduced by the triazines. Alachlor, dinoseb, and fluometuron inhibited growth of some algae at higher concentrations while 2,4-D and profluralin did not inhibit growth at the concentrations tested. Photosynthesis was greatly inhibited by the triazines, even at the 0.1 μM concentration. Fluometuron was very toxic to the blue-green algae but had less effect on the green algae tested. Lyngbya was most susceptible to photosynthesis reduction by the herbicides. The concentrations of herbicides tested had little effect on respiration of the algae species. It appears that effects on algal growth were due primarily to inhibition of photosynthesis rather than to other metabolic processes.     

Effect of 4-amino-6-methyl-3-phenylamino-l,2,4-triazin-5(4H)-one on the lignification process catalysed by peroxidase from lupin (lupinus albus)

The molecular action of herbicides with a triazine structure, such as atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and metribuzin (4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one), has been related to their inhibition of the electron carrier system between chloroplastic photosystems II and I. This report provides evidence that 4-amino-6-methyl-3-phenylamino-1,2,4-triazin-5(4H)-one, a recently synthesised triazine, structurally analogous to metribuzin, causes a powerful inhibition of the cell-wall lignification catalysed by peroxidase from lupin. The two reactions involved in this lignification process are: oxidative polymerisation of coniferyl alcohol and the generation of hydrogen peroxide at the expense of NADH oxidation.     

Hydrolysis of the triazine herbicide,cyanazine

The hydrolysis of cyanazine

1 Cyanazine is the proposed common name for the herbicide sold under the Shell registered trade name BLADEX.

(2-chloro-4-cyanoisopropylamino-6-ethylamino-1,3,5-triazine) has been studied using ¹⁴C-ring labelled compound over a temperature range of 25° to 75 °C and over a range of pH values from 1.5 to 12. The activation energies and the activation entropy changes during hydrolysis showed there was a different mechanism under acid and alkaline conditions. The only product identified after hydrolysis in acid solutions was 2-hydroxy-4-carboxyisopropylamino-6-ethylamino-1,3,5-triazine. In alkaline solution the same hydroxy-acid was the end-product, but 2-chloro-4-amidoisopropylamino-6-ethylamino-1,3,5-triazine was isolated as an intermediate. The variation of the specific rate constants with temperature for hydrolytic catalysis by H⁺, OH^? was determined, thus enabling the hydrolytic half-life of cyanazine to be calculated at any pH and temperature.     

Cyanazine metabolism in corn,fall panicum,and green foxtail*

The metabolism of cyanazine (2-chloro-4-(1-cyano-1-methyl-ethylamino)-6-ethylamino- 1,3,5-triazine) by corn (Zea mays, L.), fall panicum (Panicum dichotomiflorum Michx.), and green foxtail (Setaria viridis L.) was compared. Cyanazine metabolism by plants at the four-leaf stage was examined by thin-layer chromatography following foliar or root treatments with ¹⁴C-cyanazine. Five days following foliar ¹⁴C-cyanazine applicalion, fall panicum and green foxtail contained a larger number of water- and chloroform-soluble metabolites than corn, whereas, following root treatment, the opposite was true. Corn rapidly hydrolysed the nitrile group and hydroxylated the two-position on the triazine ring. Accumulation of the dealkylated cyanazine was evident in green foxtail, the most susceptible of the species studied. Metabolism of cyanazine supplied to the roots appeared to differ from foliar treatments in the weed species as more unchanged cyanazine was recovered. Rapid metabolism of cyanazine by corn roots provided evidence for an active cyanazine detoxication mechanism in the roots.     

Measurement of simazine residues in chickpeas,Cicer arietinum,by gas–liquid chromatography

A method is described for the measurement of simazine [2-chloro-4,6-bis(ethylamino)-1,3,5-triazine] residues in chickpeas (Cicer arietinum). Ground chickpea samples were extracted with dichloromethane, followed by clean-up on alumina. Gas-liquid chromatography using metribuzin [4-amino- 6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one] as internal standard with thermionic detection was used to quantify simazine residues. The limit of detection was 0.02 mg kg^?1 and the recoveries of simazine from chickpea samples (0.1–4 mg kg-1) averaged 92%.     

Interaction between optical isomerism and plant pharmacological action,change of modes of action and chirality of 1-(α-methylbenzyl)-3-p-tolylurea

The optical isomers, (R)-1(α-methylbenzyl)-3-p-tolylurea ((R)-MBU) and (S)-1-(α-methylbenzyl)-3-p-tolylurea ((S)MBU), which are analogues of daimuron [1-(α,α-dimethylbenzyl)-3-p-tolylurea], a herbicide for Cyperaceae weeds and a safener for paddy rice, exhibited different biological responses. These two physiological properties of daimuron were observed separately in (R)-MBU and (S)-MBU. Only (R)-MBU had herbicidal activity against Cyperaceae weeds, while the (S)-isomer was a more effective safener against bensulfuron-methyl (BSM) injury of rice seedlings than was (R)-MBU. (S)-MBU promoted root growth of rice seedlings, but the (R)-enantiomer inhibited root growth. (S)-MBU was a more potent inhibitor than (R)-MBU on PS II reaction of spinach broken chloroplasts. Furthermore, (S)-MBU and (R)-MBU showed cross intergenus selective phytotoxicity among the Gramineae plants, Oryza sativa L. (rice, cv. Tsukinohikari, japonica), Triticum aestivum L. (wheat, cv. Norin No. 61) and Echinochloa crusgalli var. frumentacea Wight, on root growth inhibition in the dark.     

Studies of the mechanism of action of asulam in plants. Part I: Antagonistic interaction of asulam and 4-aminobenzoic acid

Studies have been carried out on the herbicidal action of asulam [methyl (4-aminophenylsulphonyl)carbamate] and sulphanilamide, alone or in association either with 4-aminobenzoic acid (4ABA) or 4, 6-diamino-1-(3, 4-dichlorophenyl)-1, 2-dihydro-2, 2-dimethyl-1,3,5-triazine (DCDT). The soaking of wheat seeds (Triticum estivum L.) for 12 h at 30°C in asulam and DCDT in a 10:1 ratio doubled the inhibition of root growth produced by soaking in asulam alone; the addition of 4ABA partially reversed the activity of asulam. Foliar applications of a mixture of asulam + DCDT (1.1 + 0.55 kg ha^?1) markedly increased the activity of asulam in susceptible wheat, wild oat (Avena fatua L.), tolerant flax (Linum usitatissimum L.), and in Stellaria media L. The activity of asulam at 1.1 kg ha^?1 was reversed by 4ABA at 2.2 kg ha^?1 by about 50% in wheat and wild oat, 82% in flax and 100% in S. media. The results indicate that asulam and sulphanilamide act by similar mechanisms in apparently inhibiting the biosynthesis of folic acid.     

Triazine herbicide residues in central European streams

Triazine herbicide residues were monitored in the rivers Adour, Danube, Garonne, Herault, Loire, Marne, Oise, Rhine, and Rh?ne from spring 1976 to fall 1977 to determine whether the continued use of the compounds resulted in accumulations of undesirable residues in the streams. Samples were generally collected monthly or bimonthly and analyzed for the parent compounds atrazine, simazine, terbumeton, terbuthylazine, and dealkylated metabolites GS 26571 (2-amino-4-etert-butylamino-6-methoxy-1,3,5-triazine) and G 30033 (2-amino-4-chloro-6-ethylamino-1,3,5-triazine). The compounds were extracted into dichloromethane and quantitated by gas chromatography (GC) with nitrogen-specific detection. Selected results were verified by GC with mass fragmentographic detection. Limit of detection was usually 0.4 mg/m3; 80 percent of all results were below 0.4 mg/m3, 14 percent were 0.4-1 mg/m3, 6 percent were 1-10 mg/m3, and 0.3 percent were higher than 10 mg/m3. Detectable residues were mainly atrazine from the downstream sampling sites. Residues usually peaked during June.     

Effect of halomethyl-1,3,5-triazines on nitrification of ammonia

Nitrification inhibitory activity of halomethyl-1,3,5-triazines was determined by measuring the inhibitory activities on ammonia-oxidation to nitrate (NO₃⁻-N) in an upland soil and on ammonia-oxidation to nitrite (NO₂⁻-N) by Nitrosomonas europaea ATCC 25978 (ATCC) and Nitrosomonas sp TK 794 (TK). Within the chlorinated trimethyl-1,3,5-triazines, those bearing at least one trichloromethyl group inhibited nitrification more strongly, both in soil and in cell suspension of ATCC, than other mono- or dichlorinated methyl-1,3,5-triazines. Introduction of an amino group to 2,4,6-tris(trichloromethyl)-1,3,5-triazine gave 10- and 100-fold increases of nitrification inhibitory activity in soil and ATCC cell culture, respectively. Within the trihalomethyl-1,3,5-triazines, those having tribromomethyl group(s) exhibited rather weaker nitrification inhibition in soil than the corresponding trichloromethyl-1,3,5-triazines, although they showed a strong inhibition in cell suspension. Ammonium oxidation in ATCC was inhibited more strongly than that in TK. In QSAR studies, the optimum log P values were calculated as c 4.30. By using this value it will become possible to design highly active trichloromethyl-1,3,5-triazine nitrification inhibitors.     

Extraction and identification of a new degradation product of atrazine in the soil

Gas-chromatographic analyses of extracts of soil samples from plots, treated with a 50% atrazine wettable powder at dose rates of 2 and 4 kg a.i. ha^?1, showed the presence of a new atrazine degradation product. This product was isolated, concentrated and purified by column chromatography and high-performance liquid chromatography. The chromatographic properties of this material were identical with those of a product isolated from a 0.02% methanolic solution of 2-amino-4-chloro-6-isopropyl-amino-1,3,5-triazine that had been stored under laboratory conditions. A combined gas-liquid chromatographic/mass spectrometric assay identified the new product in soil as 2-isopropylamino-4-methoxy-6-methylamino-1,3,5-triazine.     

Phytotoxic activity of Chinese violet (Asystasia gangetica (L.) T. Anderson) and two phytotoxic substances

Chinese violet (Asystasia gangetica (L.) T. Anderson) is a perennial invasive weed belonging to Acanthaceae. Leaves of this weed have been suggested to possess phytotoxic activity. However, phytotoxic substances in this weed have not yet been reported. Therefore, the present study investigated phytotoxic activity of Chinese violet extracts and phytotoxic substances. The extracts of Chinese violet leaves inhibited the root and shoot growth of cress, lettuce, alfalfa, barnyard grass, ryegrass, and timothy, where the level of inhibition increased with increasing extract concentrations. Bioassay‐guided separations of the extracts led to isolation of two phytotoxic substances, indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol. Indole‐3‐carboxaldehyde significantly inhibited the root and shoot growth of cress at concentrations ≥100 and 30 μmol L^?1, respectively, and concentrations of the substance required for 50% growth inhibition were 210 and 127 μmol L^?1 for cress roots and shoots, respectively. The other substance, (6R,9S)‐3‐oxo‐α‐ionol, was reported to have strongly inhibited cress roots and shoots. The present results suggest that Chinese violet contains two phytotoxic substances indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol, and those substances may play an important role in the phytotoxic activity of Chinese violet.