摘要:

Summary:Experiments were conducted in a controlled environment growth room to compare the phytotoxicity of five formulations of clopyralid and to determine the effect of post‐treatment simulated rainfall applications on the efficacy of these formulations. Clopyralid, formulated as the acid, monoethanolamine salt, potassium salt, 2‐ethylhexyl ester or 1‐decyl ester was applied toCirsium arvenseorPolygonum convolvulusat the 8–10 and 4–6 leaf stage of development, respectively.Based on the shoot and root dry weight data from both species, the 2‐ethylhexyl ester was consistently less phytotoxic than the other four formulations. With respect toCirsium arvenseshoot and root dry weight, there was no difference in efficacy between the acid, monoethanolamine salt, potassium salt and 1‐decyl ester. Root dry weight changes ofPolygonum convolvulusdid not correlate well with an increase in dose of the five formulations. Maximum increase in stem diameter ofPolygonum convolvulusoccurred after application of 100 g a.e. ha−1of the acid, monoethanolamine salt, potassium salt and 1‐decyl ester whereas with the 2‐ethylhexyl ester, the maximum increase occurred after application of 200 g a.e. ha−1. Simulated rainfall was applied 3, 6, 9 or 12 h after application of 200 g a.e. ha−1of the five clopyralid formulations to both species. Rainfall reduced the efficacy of clopyralid, regardless of the formulation or species. The 2‐ethylhexyl ester was less efficacious than the other four formulations, irrespective of the tim

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01708.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:The activity of imazapyr and glyphosate againstImperata cylindricawas studied in field and glasshouse experiments using two methods of direct contact application; a rope‐wick wiper and a cloth soaked in herbicide solution. The effect of concentration and position of application on herbicide uptake and translocation was also measured. At the lowest dose of imazapyr (5 mg acid equivalent (a.e.) per plant), phytotoxicity was greater from applications by a rope‐wick wiper than by a cloth. However, when the dose of imazapyr was increased, the cloth applicator was more effective than the rope‐wick wiper. At all doses of glyphosate, rope‐wick application was more effective than wiping with a cloth. Herbicide performance in the glasshouse was similar to that in the field. Radiotracer studies showed that increasing the concentration of imazapyr, while keeping herbicide dose constant, decreased uptake and translocation of radiolabel. In contrast, the rate of uptake of14C‐glyphosate increased with increasing herbicide concentration. Position of application did not significantly affect the amount of uptake and translocation of radiolabel to the rhizomes. It is concluded that rope‐wick wipers are more effective than wiping with a cloth for applying imazapyr and glyphosate toI. cylindrica, provided that the concentration of imazapyr does not exceed 10

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01709.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:The germination and growth of three strains of gooseweed (Sphenoclea zeylanicaGaertn.) that showed susceptibility, moderate susceptibility, and tolerance for foliar‐applied 2,4‐D isobutyl ester were studied in the laboratory and greenhouse. The plants were isolated from samples collected from major rice (Oryza sativaL.) growing areas in the Philippines. The seeds of all three strains possessed dormancy; light stimulated germination but did not completely overcome dormancy. Without N application, stem elongation and leaf production did not differ among the strains. With 60 kg N ha−1, the susceptible and moderately susceptible strains responded better than the tolerant strain, the difference being apparent at 6 weeks after emergence. Measurements of the leaf cuticle showed significant differences among the strains starting at the 8‐ to the 10‐leaf stage, a trend that paralleled their response to 2,4‐D. Adding a surfactant to the spray formulation nullified the differential responses. Implications for managing the weed and correlations with current field observations ar

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01710.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Zusammenfassung:In einem zweijährigen Versuch auf zwei Standorten (Sand‐ und Lehmboden) wurde Isoproturon allein und in Kombination mit Dinoseb‐acetat und Bifenox zum Nachauflauf Winter (NA‐W) Termin und zum Nachauflauf Frühjahr (NA‐F) Termin in Wintergerste und Winterweizen eingesetzt. Obwohl nach einer Nachauflauf‐Winter Behandlung die anfänglichen Herbizidbelastungen im Böden höher waren, sind nach unseren Ergebnissen im Vergleich zu einer Nachauflauf‐Frühjahr Behandlung am Ende der Vegetationsperiode keine erhöhten Rückstände von Isoproturon zu erwarten. Die DT‐50‐Werte von Isoproturon in den beiden Versuchsjahren und Böden lagen zwischen 12 und 33 Tagen, die DT‐90‐Werte schwankten im Bereich von 34 bis 68 Tagen. Ein Einfluß der mit Isoproturon kombinierten Wirkstoffe auf dessen Abbau im Boden war nicht festzustellen. Eine bessere Unkrautwirkung der NA‐W‐Behandlung führte besonders bei starke

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01711.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:The influence of temperature, humidity and simulated rain on thiameturon‐methyl activity was examined on white mustard (Sinapis albaL.) plants grown in controlled environment cabinets or in a glasshouse. The performance of thiameturon‐methyl was markedly improved with increasing temperature and humidity. Addition of a non‐ionic surfactant increased the activity of thiameturon‐methyl, reduced the in fluence of humidity on herbicide performance but had no effect on the influence of tempera ture on herbicide activity. Increasing the amount of simulated rain from 0.11 to 3 mm reduced the activity of thiameturon‐methyl. However, reduction in activity by 3 mm rain became less pronounced as the interval between herbicide application and rain treatment was in creased from 0.5 to 6 h. With a 6‐h interval 3 mm rain had little effect. Rain intensity was found only to have a minor influence on the rainfast‐ness of thiam

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01712.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:DPX‐A7881, methyl 2‐[(4‐ethoxy‐6‐methyl‐amino‐1, 3, 5‐triazin‐2‐yl)carbamoylsulphanoyl] benzoate, is a sulfonylurea herbicide being developed in Canada and Europe for post‐emergence broadleaf weed control in spring and winter rapeseed. Growth room studies were conducted to determine the environmental factors affecting the herbicidal activity of DPX‐A7881 applied post‐emergence on winter rapeseed (Brassica napusuL. ‘Tandem’) and on a closely related weed species,Sinapis arvensisL. (wild mustard).Laboratory tests were carried out at tempera tures ranging from 2–26°C, at relative humidities from near 40% to>95%, with rain‐free periods from 0.25–8 h after herbicide application, at soil moisture contents from 50–200% of field capacity, and with irradiances from 23–450 μEm−2s−1Significant control ofS. arvensiswas demonstrated for all treatments except under poor growing conditions at the lowest temperatures and irradiances tested. After two weeks' exposure to each of the tem perature treatments, the herbicide maintained control ofS. arvensisduring a subsequent week of favourable growing conditions. Relative humidity, soil moisture or simulated rainfall did not significantly alter the herbicidal activity of DPX‐A7881 onS. arvensis. DPX‐A7881 showed a high degree of crop safety onB. napus. The herbicide did not significantly reduce the dry weights ofB. napusgrown

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01713.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:Silene vulgaris (Moench) Garcke, grown from seed or from crown buds, exhibited three dis tinct growth phases; establishment, reproduc tive and post‐reproductive. The establishment phase was characterized by rapid accumulation of shoot biomass, high relative growth rates (RGRs) and leaf area ratios (LARs). The sexual reproductive phase was characterized by a rapid increase in floral and seed biomass, minimal root development, and declining RGRs and LARs. In the post‐reproductive phase, root and crown biomass increased rapidly concomitant with the development of regenerative buds; low RGR and LAR values occurred during this phase. Although similar growth phases were identified in both the first (grown from seed) and second years (grown from crown buds) of growth, LARs and RGRs were lower in the second than in the first year. In the second year of growth, plants exhibited a continual increase in below‐ground biomass throughout growth, including the flowering period, a feature which was absent in the first year of g

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01714.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary:Seeds ofAvena fatuaL. and)A. sterilisL. were germinated under a wide range of temperatures (5–30°C) and osmotic potentials (−25 to −1400 KPa) in order to characterize their responses to these two environmental factors. Although both species behaved similarly at moderate temperatures, different responses were observed at the two extremes.)A. sterilisgerminated and emerged in a higher proportion thanA. fatuaat temperatures below 10°C but the opposite was true at temperatures above 20°C. Although the rates of these two processes were similar in both species up to 18°C, above this temperature the germination and emergence of)A. steriliswas considerably delayed in comparison with that ofA. fatua. The effect of decreasing osmotic potentials in reducing the germination was more pronounced inA. sterilisthan inA. fatua. However, no differences were observed in the emergence responses of either species. The adaptative advantages of these characteristics and their relationship with the geographic distribution of the two species is

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01715.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Résumé:L'évolution du potentiel semencier a été suivie pendant huit années sur quatre parcelles ex périmentales assolées (orge et pois de prin temps, blé d'hiver) différant par le type de travail du sol (profond ou superficiel) et de désherbage chimique (absent ou sélectif). Nos résultats montrent que la répartition verticale des semences dans le sol (exprimée en pour centage) n'est pas modifiée par le travail du sol pour les parcelles désherbées alors que des différences apparaissent dès la cinquième année pour les parcelles non désherbées. Globalement le stock semencier augment sur les parcelles non désherbées alors qu'il reste relativement stable sur les autres parcelles, cette augmenta tion étant plus importante sur la parcelle travaillée superficiellement. Néanmoins, une analyse plus détaillée de l'évolution des dénombrements selon trois niveaux d'enfouisse ment permet de nuancer ces observations et de définir trois types de comportement de l'évolu tion des semences dans la couche arable. Enfin, la richesse spécifique du potentiel semencier reste stable mais la structure de la commun auté se modifie par augmentation ou diminution de l'abondance de certaines espèces selon l'abs

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01716.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1990.tb01717.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY