ALBERT

Notes: The longterm control of bracken (Pteridium aquilinum) following applications of asulam was studied for 5 years al a site in the West of Scotland; there was no post-spray management. The time of treatment was found to be of considerable importance, satisfactory long-term control being obtained only when 4.4–8.8 kg/ha were applied around the stage of full frond expansion (26 July–16 August). Application of 4.4 kg/ha asulam on 26 July decreased frond density by 99, 95, 85, and 73% in the 4 years following treatment; about 50% recovery was observed in the fifth year. The latter may be partially due to the encroachment of rhizomes from the adjacent untreated plots and the lack of post-spray management. Examination of rhizomes dug from 1 m2 areas showed that asulam killed more than 90% of the active frond buds and apices in the first year, but left undamaged 48% of the dormant buds on the deeper rhizome branches; the latter appeared to be the main source of reinfestation of treated plots in subseqquent years. The total number of living buds increased from 17% of the untreated in the first year to 38% in the fifth year; the majority of these buds were dormant. Formulation of asulam (4.4 kg/ha) with 1% ethylan CP only improved the reduction in frond density over a 4-year period by 10%. Recherches sur le mode d'action de l'asulame sur la fougère (Pteridium aquilinum L. Kuhn). III, Elimination durable de la fougère.Lélimination durable de la fougére (Pteridium aquilinum) a la suite d'applications d'asulame a éte etudiee pendant 5 annees dans une station de I'ouest de I'Ecosse; il n'y a pas eu d'autre intervention apres le trailement. W a ete constate que Vepoque du traitement avait une importance considerable, une elimination durable n'ayant pu etre obtenue qu'en appliquant 4,4 a 8,8 kg/ha d'asulame au stade de plein developpement des frondes (26 juillet-16 aout), L'application de 4,4 kg d'asulame le 26 juillet diminua la densite des frondes de 99, 95, 88, et 73% au cours des 4 annees suivant le traitement; une repousse d'environ50% fut observee la cinquieme annee, Ce resultat final peut etre du en partie a I'empietement de rhizomes provenant des parcelles adjacentes non traitees et a I'absence d'intervention apres le traitement. L'examen des rhizomes extraits sur des surfaces de 1 m2 montra que I'asulame avait tue plus de 90% des bourgeons et des apex des frondes en activite au cours de la premiere annee, mais n'avait pas endommage 48% des bourgeons dormants situes sur les ramifications les plus profondes des rhizomes; ce fait est apparu comme la cause principale de la reinfestation des parcelles traitees au cours des annees suivantes. Le nombre total des bourgeons vivants est passe de 17% des temoins la premiere annee a 38% la cinquieme annee; la majorite de ces bourgeons etaient dormants. La formulation de I'asulame avec 1% seulement d'etylan CP” a augmente de 10% la reduction de la densite des frondes au cours de la periode de 4 ans. Untersuchungen zur Wirkuttgsweise von Asulam bei Adlerfarn (Pteridium aquilinum L. Kuhn). III. Langfristige BekdmpfungIn einem Versuch in Westschottland wurde die langfristige Bekampfung von Adlerfarn (Pteridium aquilinum) nach Asulam-Behandlungen uber 5 Jahre untersucht. In diesen Versuchen wurden nach der Herbizidbehandlung keine weiteren Bekampfungsmassnahmen durchgefiihrt. Es konnte festgestellt werden, dass der Bekampfungszeitpunkt von erheblicher Bedeutung ist. Eine befriedigende langfristige Bekampfung wurde nur erzielt, wenn 4.4–8.8 kg/ha zum Zeitpunkt der vollen Wedelentwicklung (26, Juli-16. August) angewendet wurden. Eine Behandlung mit 4,4 kg/ha Asulam am 26, Juli fuhrte in den 4 Jahren nach der Applikation zu einem Ruckgang der Wedeldichte um 99, 95, 85 und 73%, und im fiinften Jahr betrug die Wedeldichte wieder etwa 50% der ursprunglichen. Das letztere lasst sich teilweise mit dem Eindringen von Rhizomen aus benachbarten unbehandelten Parzellen und dem Fehlen weiterer Massnahmen mach der Herbizidbehandlung erklaren. Die Untersuchung von I m2 grossen Flachen zeigte, dass durch Asulam im ersten Jahr iiber 90% der aktiven Wedelknospcn und -apices getotet wurden, aber 48% der dormanten Wedelknospen und -apices der tieferliegenden Rhizomstijcke unbeeinfiusst blieben. Diese Organe scheinen die Hauptursache der Wiederverseuchung in den folgenden Jahren gewesen zu sein. Die Gesamtzahl an lebenden Knospen nahm, bezogen auf Unbehandelt, von 17% im ersten Jahr auf 38% im fiinften Jahr zu, die meisten Knospen waren aber dormant. Zusatz von 1% Ethylan CP zu Asulam (4,4 kg/ha) verbesserte im Beobachtungszeitraum von 4 Jahren die Wirkung (Verminderung der Wedeldichle) nur um 10%.

Notes: The effect of asulam (methyl (4-aminobenzenesulphonyl) carbamate) on the synthesis of RNA and protein was investigated in bracken sporeling plants and excised rhizome bud tissue. Foliage application of asulam (4.4 kg/ha) reduced the RNA levels in frond buds and young fronds within 3 days, while protein levels were significantly reduced after 14 days. A significant reduction in respiratory activity of buds was observed after 2 weeks, the level of inhibition being 54% after 8 weeks. During a 3-h incubation period, O2 uptake by excised bud issue was stimulated by 5 and 10 ppm asulam and inhibited by higher concentrations; 32P uptake was inhibited at all concentrations. Asulam (5 ppm and above) inhibited bud growth and reduced RNA and protein levels in incubated buds (20 h at 30°C), and the incorporation of [14C]orotic acid into RNA and [14C]leucine into protein. Reduction of RNA levels and inhibition of [14C]ladenine incorporation into RNA in buds occurred entirely in the ribosomal and supernatant fractions of the cellular extract. Inhibition of RNA synthesis by asulam (50 ppm) as measured by [14C] orotic acid incorporation into RNA was completely antagonized by CEPA (3-chloroethylphosphonic acid) (50 ppm) and partially by 2,4-D (2,4-dichlorophenoxyacetic acid) (50 ppm) and GA (Gibberellic acid) (50 ppm). These results suggest that the interference of asulam with RNA and protein synthesis at the metabolically active sinks (rhizome buds) could be one of its major mechanisms of action in bracken.

Notes: Studies of the absorption and translocation of foliage-applied ring-labelled [14C]asulam [methyl (4-aminobenzenesulphonyl) carbamate] were carried out using glasshouse and field-grown bracken plants. Translocation of 14C from the treated frond was primarily according to a 'source to sink’pattern with intense accumulation of radioactivity in the metabolically active sinks viz. rhizome apices, frond buds, root tips and young frond tissue. In the case of field bracken, translocation and distribution of 14C was extensive in the rhizome system, accumulation occurring in the active as well as dormant buds situated on the non-frond-bearing and storage rhizome branches. Treatment of fully expanded fronds with 100μl of [14C]asulam (1 mg, 1.0–1.5 μCi) as 2 μl droplets resulted in a rapid initial uptake during the first week, followed by progressive entry and distribution with time. Basipetal translocation to the rhizome system was positively correlated with total uptake. High humidity (95%) and high temperature (30°C) stimulated uptake and subsequent basipetal translocation to a considerable degree. Uptake was greater through the stomatal-bearing abaxial than through the adaxial cuticle. Incorporation of a surfactant (Tergitol-7, 0.1%) increased penetration by up to 30%. Uptake declined markedly as the frond aged, while translocation was predominantly acropetal in young treated fronds, becoming exclusively basipetal when the fronds matured. Optimum uptake and maximum distribution of [14C]asulam in the rhizome and its associated buds was achieved when treatments were applied to almost fully expanded fronds. The translocated 14C (asulam and possibly some of its metabolites) showed a considerable degree of persistence in the rhizome system, 8% of the applied activity still remaining in the rhizome 40 weeks after treatment.

Notes: Summary. The growth has been tested in vitro of selected species of fungi, yeasts, bacteria, actinomycetes and green algae in the presence of the acetic and α-butyric acid forms of MCPA, 2,4–D and 2,4,5–T. The results show that at concentrations approximating to field rates of application, these chemicals were harmless. At much higher concentrations (above 500 ppm), however, the α-butyric acids were found to be highly toxic whereas the acetic acids has no effect on growth.

Notes: Summary. The herbicidal activity of MCPA and MCPB was compared using three species of unicellular algae grown in liquid mineral salt medium. MCPB inhibited growth, respiration and phosphate uptake to a greater degree than MCPA and appears to be inherently toxic at concentrations of at least 2·5 × 10−4 M. The enhanced activity of MCPB coincided with more efficient absorption. Uptake of both compounds appears to be optimal at pH conditions favouring movement as the undissociated molecule.Facteurs infiuencant l'efficacite herbicide du MCPA et du MCPB sur trois espèces d'algues micro-scopiquesRésumé. L'activité herbicide du MCPA et du MCPB a été comparée en utilisant trois espéces d'algues unicellulaircs cultivées en milieu liquide renfermant des sets minéraux. Le MCPB inhibe la croissance, la respiration et l'absorption du phosphate à un degré plus éevé que le MCPA et il semble être essentiellement toxique à des concentrations d'au moins 2,5 × 10−4 M. L'activité plus grande du MCPB coïncide avec une absorption plus complète. L'absorption des deux composés semble étre optimale aux conditions dec pH favorisant leur migration sans dissociation de la molécule.Faktoren, welche die hrbizide Wirkung von MCPA und MCPB gegen drei Mikro-Algen-Arlen beeinfiussenZusammenfassung. Die herbizide Wirksamkeit von MCPA und MCPB wurde bei drci Arten einzelliger Algen, die in flüssigem Mineralsalzmedium angezogen wurden, vcrglichen. MCPB hemmt Wachstum, Respiration und Phosphataufnahme starker als MCPA und ist offcnsichdich in Konzentrationen von mindestens 2,5 × 10−4 M absolute toxisch. Die bessere Wirkung von MCPB geht mit einer besseren Absorption parallel. Die Aufnahme beider Substanzen ist offensichtlich unter solchen pH-Bedingungen optimal, die den Transport in Form von undissozierten Molekülen begünstigen.

Notes: [Auszug] 'SAFETY' is the current climate and there are stringent conditions governing the registration of pesticides, which are by their nature, biologically very active. These include microbiological investigations. This book is an attempt, and a very successful one, to bring together much of the ...

Notes: [Auszug] Pesticides identified as contaminants in birds or their eggs in the wild have all been, so far as we are aware, organochlorine insecticides. Yet it has been found3 that a number of herbicides show considerable persistence in the soil and should thus be susceptible to passage along a food chain and ...

Notes: [Auszug] Table 1 (1) Dose given: 200 p.p.m. = 10 mg/egg. (Selected compounds only.) Percentage of hatch 100 Dieldrin 90 DDT, dicofol, gamma-BHC, TDE 80 Methoxychlor 70 Malathion t, ethion 0 Binapacryl, mecarbam J (2) Dose given: 100 p.p.m. = 5 mg/egg. (All compounds.) Percentage of hatch 100 DDT, ...