• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.279-286
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• 2002

To improve the growth inhibition activities and selectivities for quinclorac family, novel 3-substituted phenyl-5-(3,7-dichloro-8-quinolinyl)-1,2,4-oxadiazole derivatives as the substrate were synthesized and their the activities ($pI_{50}$) against shoot and root of rice plant (Oryza sativa L.) and barn-yard grass (Echinochloa crus-galli) were measured. And the quantitative structure-activity relationships (QSARs) between physicochemical parameters of the substitutents (R) on phenyl group and the activities ($pI_{50}$) were analyzed quantitatively. According to the SAR analyses, the substrates of planar conformation showed higher herbicidal activities against barnyard grass than rice plant. The activities against rice plant depend on the electronic effect (shoots: ${\sigma}_{opt.}=0.49$ & root: $R_{opt.}=-0.15$) of substituents, whereas the activities against shoots and roots of barnyard grass depend on hydrophobicity (${\pi}_{opt.}=0.37{\sim}2.40$). There were conditions of selective growth inhibition activity against barnyard grass when such a ortho-substituted electron donating substituents showing the hydrophobicity value, ${\pi}=2.40$ were introduced on the phenyl ring. The 2-tolyl substituent predicted from SAR equations was expected to have better growth inhibition activity and selectivity (${\Delta}pI_{50}=1.26$) for barnyard grass.

• The Korean Journal of Pesticide Science
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• v.7 no.2
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• pp.108-116
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• 2003

A series of new quinclorac family, herbicidal 3-phenyl-5-(3,7-dichloro-8-quinolinyl)-1,2,4-oxadiazole derivatives as substrate were synthesized and their growth inhibition activity $(pI_{50})$ against root and shoot of rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) were determined. And then comparative molecular field analysis (CoMFA) and molecular holographic quantitative structure- activity relationship (HQSAR) were compared in terms of their potential for predictiability. The statistical results were suggested that HQSAR based model had better predictability than CoMFA model. The selective factors to remove barnyard grass take electron withdrawing groups which can be created positive charge and steric bulky on the phenyl ring. Results revealed that the unknown 2,6-dichloro-substituent, U5 and 2,4,6-trichloro-substituent, U6(${\Delta}pI_{50}$=CoMFA: 1.18 & HQSAR: 1.82) were predicted as compound with higher activity and selectivity.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.157-165
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• 2006

This study was initiated to investigate herbicidal selectivity margin with annual bluegrass and bentgrass according to growth stages through herbicidal spectrum of bispyribac-sodium and therefore to examine application possibility to prevent annual bluegrass selectively. The herbicidal efncacy by pre-emergence application was generally low. But a high herbicidal efficacy was observed over 90% for Shehpherd's purse. Foliar treatment resulted in a higher herbicidal efficacy in all tested plants except dallisgrass, lovegrass, curled dock and bentgrass as compared with pre-emergence application. We found bispyribac-sodium could be used as a selective weeding chemical between annual bluegrass and bentgrass. In regard to dose-responses to the growth stage, annual bluegrass was more susceptible to bispyribac-sodium than bentgrass for the same dosage. Particularly, bispyribac-sodium application in inflorescence emergence stage showed a greater herbicidal selectivity margin of 6.8 times with annual bluegrass over creeping bentgrass after 28 days from the application. These data demonstrated that annual bluegrass was more sensitive to bispyribac-sodium over creeping bentgrass.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.38-46
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• 2013

With increasing environmental issues from synthetic chemical herbicides, microbe-originated herbicides could be a fascinating alternative in current agriculture. We isolated Streptomyces strains that produced herbicidal active metabolite(s) against a grass weed Digitaria sanguinalis. According to the result from 16S rDNA sequence comparison with the close strains, the best isolate (Code name MS-80673) was identified as Streptomyces scopuliridis KR-001. The closest type strain was Streptomyces scopuliridis RB72 which was previously reported as a bacteriocin producer. The optimal culture condition of S. scopuliridis KR-001 was $28^{\circ}C$, pH 7.0 and culture period 4 to7 days. Both of soil and foliar application of the crude culture broth concentrate was effective on several troublesome or noxious weed species such as a Sciyos angulatus in a greenhouse and field condition. Phytotoxic symptoms of the culture broth concentrate of S. scopuliridis KR-001 by foliar application were wilting and burndown of leaves, and stems followed by discoloration and finally plant death. In crops such as rice, wheat, barley, hot pepper and tomato, growth inhibition was observed. These results suggest that the new S. scopuliridis KR-001 strain producing herbicidal metabolites may be a new bio-herbicide candidate and/or may provide a new lead molecule for a more efficient herbicide.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.212-221
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• 2017

An actinomycetes isolate G-0299 obtained from a forest soil showed strong phytotoxic activity to Digitaria ciliaris. For the foliar application study, the culture filtrate of the isolate G-0299 showed strong herbicidal activity only to D. ciliaris among the 12 monocot and 5 dicot weed species. And herbicidal activity at a concentration of 500, 250, 125 and $62.5{\mu}gmL^{-1}$ of culture filtrate was 100%, 98%, 70% and 40%, respectively. Phytotoxic symptoms of the culture filtrate by foliar application were desiccation and burn-down or bleaching of leaves and finally plant death. And then the herbicidal activity was exhibited only under the light condition. Also, chlorophyll loss of D. ciliaris leaf tissues in the light condition was much higher than in the dark condition and then chlorophyll content decreased 82%, 5%, respectively. In conclusion, our results suggest that soil bacteria, isolate G-0299 could be a good candidate for new bio-herbicide and provide a new lead molecule for a more unique herbicide.

• Korean Journal of Environmental Agriculture
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• v.15 no.4
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• pp.501-505
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• 1996

Azimsulfuron [1H-pyrazole-5-sulfonamide,N-(((4,6-dimethoxy-pyridine-2-yl-aminocarbonyl-4-(2-methyl-2H-tetrazole-5-yl)] is a new sulfonamide herbicide that selectively controls a wide range of weeds in lowland rice (Oryza sativa). It effectively controlled Cyperus serotinus, Eleocharis kuroguwai, Sagittaria pygmaea, S. trifolia, and Scirpus juncoides at 7.5 - 30 g ai/ha. In the tolerance test on grasses carried out in a nutrient solution containing 0.3 - 30 ppm of azimsulfuron, greater inhibition occurred in roots of both rice and barnyardgrass (Echinochloa crus galli) than in shoots. However, rice root was approximately 5-fold more tolerant than that of barnyardgrass. The downward movements as determined by 50% growth inhibition of S. juncoides were 4-cm in clay loam and 6.5-cm in sandy loam soil with 3-cm/day leaching for 3 days. When incubated at 20 and $30^{\circ}C$, the residual effect in clay loam soil lasted for 30 and 21 days, respectively. In a soil column applied at 15 g ai/ha of azimsulfuron followed by 3-cm/day leaching for 3 days, dry weights of S. trifolia emerging at 5, 10, and 15-cm depth were reduced to 87, 85, and 79% of the corresponding untreated control, respectively. Susceptibility of S. trifolia to azimsulfuron did not greatly vary with the emergence depth.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.263-272
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• 2012

The potential as natural herbicide of d-limonene natural agent was conducted on several weeds in a greenhouse and Sciyos angulatus in field condition. Herbicidal activity of foliar application at a concentration of 100 and 200 kg ai $ha^{-1}$ of d-limonene on seven weed species was completely killed in a greenhouse condition. Also, d-limonene at a concentration of 50 kg ai $ha^{-1}$ was completely killing on Abutilon theophrasti, Aeschynomene indica, Echinochloa crus-galli and Digitaria ciliaris 3 days after treatment. While pre-emergence treatment of d-limonene concentration of 12.5 to 200 kg ai $ha^{-1}$ showed not significant visible damages. Phytotoxic symptoms of d-limonene by foliar treatment were characterized by wilting and burn-down of leaves and stems followed by discoloration, finally, plant death. Crop selectivity at d-limonene concentration of 100 kg ai $ha^{-1}$ over to five main crops including Zea mays by foliar application was not at all. Field trial of foliar treatment with d-limonene 70 to 140 kg ai $ha^{-1}$ have effectively controled over 5~20 leaf stages of S. angulatus at the natural habitats. And herbicidal efficacy of foliar application on S. angulatus with carrier volume in field condition was increased with dose dependent manners. These results suggest that d-limonene is considered possible as herbicide, and may be further optimized for natural agent for environmental friendly natural herbicide.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.187-194
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• 1991

Absorption and translocation, and metabolism studies using $^{14}C$-naproanilide were conducted to determine selective mode of action of naproanilide in rice and paddy weeds under different temperature conditions. Absorption amount of $^{14}C$-naproanilide was greater in Cyperus serotinus and Sagittaria pygmaea than rice and Echinochloa crusgalli. Especially, absorption of $^{14}C$-naproanilide in C. serotinus was increased twice at 32 $^{\circ}C$ and 48 hour exposure conditions. $^{14}C$-naproanilide in roots was translocated to shoots very little in rice and E. crusgalli, but S. pygmaea somewhat greater translocation than the other species. In C. serotinus and S. pygmaea, susceptible weeds, metabolic rates of naproanilide into phytotoxic NOP (2-(2-naphthoxy)-propionic acid) and NOPM (methyl 2-(2-naphthoxy) propionate) were significantly greater than in rice and E. crugalli, tolerant species. Consequently, differential uptake by roots and the difference in activation metabolism of naproanilide among species may explain the possible mechanism of selectivity.

• Korean Journal of Weed Science
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• v.12 no.2
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• pp.144-157
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• 1992

The study was conducted to compare the interprete methods and examine the feasibility of mixture use of oxyfluorfen and bensulfuron in controlling principal Paddy weeds, annuals and perennials. Application ratio of both chemicals were obtained from the combinations of 5 levels(0, 5, 10, 15, 20 g ai/ha) of each chemicals, respectively. All the treatments were applied at 5 days after transplanting and water was maintained at 3.0cm in depth. Shoot fresh-weight of weeds was assessed at 35 days after treatments. Data obtained was analysed by Colby, Isobole, Calculus, Regression and EQM method, respectively. The results from the analysis of variance on the principal weeds treated with oxyfluorfen and bensulfuron showed significant interactions at 1% level on both Echinochloa crus-galli and Eleocharis Kuroguwai, and total species at 0.5% level on both Potamogeton distinctus and Cyperus serotinus, but non significant on Scirpus juncoides and Sagittaria pygmaea. Thereafter, the results of the models applied to Echinochloa crus-galli, Eleocharis kuroguwai and total species were as follows ; 1. The Colby method gave values nearly identical to regression estimate method (both multiplicative models) as provided by Akobundu et al. The Colby method and Regression method indicated synergistic toward Echinochloa curs-galli, and total species, but antagonistic toward Eleocharis kuroguwai. 2. The Isobole method shows synergism on Echinochloa crus-galli at $ID_{50}$, and total species at $ID_{60}$ on Eleochari kuroguwai. 3. The Calculus method gave positive signs for the first differentiation and negative signs for the second differentiation except for some rates on Echinochloa crus-galli and total species, but reverse on Eleocharis kuroguwai. These result does not agree with the observed values. 4. ${\theta}$ value from the EQM method was greater than one at all combinations. This result was quite different from those of other methods. 5. The various models did not show the same results, but mixture of oxyfluorfen and bensulfuron tend to have synergistic effect. Weeding effect also was high. Treatment in terms of two chemical combination was expected to reduce rates, and to enhence weeding efficacy compared with single treatment.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.52-63
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• 1998

A novel quinolineoxadiazoles, substituted the carboxylic acid group with 1,2,4-oxadiazole radicle, of KSC-16960 and related compounds were evaluated to examine the herbicidal activity, crop injury and residual effect of after-vegetable crops compared with those of quinclorac (3,7-dichloro-8-quinolinecarboxylic acid), of which use is now banned because of its residual activity to some succeeding vegetable crops. KSC-16960 showed 2- and 3-leaf stages of barnyardgrasses effectively controlled by more than 95 and 90%, respectively, at a rate of 6.25 g/ha. The dose of KSC-16960 controlled 4- and 5-leaf stages of barnyardgrasses by more than 90% were found to be 50 g and 100 g/ha, respectively. The selectivity of KSC-16960 between direct-seeded rice and barnyardgrass was approximately 2-fold higher than that of quinclorac when they were treated to the soil. The selectivity indices of KSC-16960 and of quinclorac between 1-leaf stage of direct seeded rice and 5-leaf stage of barnyardgrass were 44 and 23, respectively, and those between 1-leaf stage of direct seeded rice and 4-leaf stage of barnyardgrass were almost 2-fold higher. Application of KSC-16960 with bentazone exhibited an additive controlling effect on several weed species, but that of quinclorac exhibited an antagonistic effect. With pyrazosulfuron-ethyl, on the other hand, both application of KSC-16960 and quinclorac showed additive interactions. Under a greenhouse condition, the residual activity of KSC-16960 to succeeding tomato plants was approximately 4-fold lower compared to that of quinclorac. KSC-16960 could be substituted for quinclorac, if it will be made some more improvement for reducing residual activity.