Uptake and translocation of 14C-glyphosate in Alternanthera philoxeroides (Mart.) Griseb. (alligator weed) II. Effect of plant size and photoperiod

Alternanthera philoxeroides, grown under 10 h short-day (SD) or 16 h long-day (LD) photo-periods, was administered foliar application of ¹⁴C-glyphosate equivalent to 27.4 μg per plant applied in 26 × 1-μl droplets. Plants were also transposed from SD to LD photoperiod and vice versa one week before treatment. The data were compared with those obtained for field-grown plants where the photoperiod gradually declined from 14.2 to 12.0 h over 10 weeks. Auto-radiography showed transport of radiolabel to below-ground parts within 3 days of treatment. Quantitative measurements of radiolabel by combustion and scintillation counting in plants harvested 3, 7 and 14 days after treatment confirmed uptake and translocation after 3 days which then remained constant. Recovery of label was incomplete, particularly in SD plants, where there was evidence of increasing leakage of radiolabel from the root system with time. Transposition of photoperiods had no effect on uptake or translocation suggesting that differences in plant size and phenology rather than photoperiod controlled behaviour. The proportion of applied radiolabel translocated from the treated leaf and retained in the plant (i.e. not exuded from the roots) was significantly lower in SD plants than LD plants with field grown plants showing highest translocation and retention in the rhizomes. However, only in SD plants (where translocation was least but plants were small) did glyphosate concentrations reach critical levels for inhibition. Absorption et transport de glyphosate C14 chez Alternanthera philoxeroides (Mart.) Griseb. II. Effet de la taille de la plante et de la photoperiode Alternanthera philoxeroides cultivé sous des photopériodes de jours courts (JC) de 10 h, ou de jours longs (JL) de 16 h, ont subi un traitement foliaire au glyphosate C14 équivalent à 27,4 μg par plante appliqué dans 26 × 1 μl gouttelettes. Les plantes ont été passées de la photopériode JC à celle JL et vice-versa une semaine avant le traitement. Les données ont été comparées avec celles obtenues pour des plantes cultivées en plein champ où la photopériode avait baissé de 14,2 à 12 h sur 20 semaines. L'autoradiographie a montré le transport du marqueur vers les parties souterraines dans les 3 jour après le traitement. Les mesures quantitatives du marqueur par combustion et scintillation, faites dans des plantes ramassées 3, 7 et 14 jours après le traitement ont confirmé l'absorption et le transport après trois jours qui demeurait ensuite constant. La récupération du marqueur était incomplète surtout chez les plantes JC, où il est apparu une augmentation de la perte du marqueur à partir du système racinaire avec le temps. La transposition des photopériodes n'a pas eu d'effets sur l'absorption et le transport donnant à penser que les différences dans la taille des plantes et la phénologie plutôt que la photopériode ont influencé le processus. La proportion de marqueur appliqué, transport de la feuille traitée et retenue dans la plante (non rejeté par les racines) était significative-ment plus basse chez les plantes JC que chez les plantes JL, tandis que les plantes cultivées en plein champ montraient un transport et une rétention dans les rhizomes plus élevés. Cependant, les concentrations de glyphosate ont attaient les niveaux critiques de l'inhibition seulement chez les plantes JC (où le transport était moindre mais les plantes petites). Aufnahme und Translokation von ¹⁴C-Glyphosat in Alternanthera philoxeroides (Mart.) Griseb. II. Einfluβ von Pflanzengröβe und Photoperiode Pflanzen von Alternanthera philoxeroides wurden im Kurtztag (10 h) oder im Langtag (16 h) angezogen und mit ¹⁴C-Glyphosat entsprechend 27,4 μg pro Pflanze mit 26 1-μl-Tröpfchen behandelt. Eine Woche vor der Behandlung wurden auch Pflanzen vom Kurztag zum Langtag und umgekehrt gestellt. Die Daten wurden mit denen von im Feld wachsenden Pflanzen mit über 10 Wochen hin graduell von 14,2 auf 12,0 h abnehmender Tageslänge verglichen. Die Verlagerung radioaktiv markierter Substanz in unterirdische Pflanzenteile innerhalb 3 Tagen nach der Behandlung wurde autoradiographisch nachgewiesen. Die quantitative Messung der Radioaktivität durch Szintillations-Zählung nach Veraschung von Pflanzen 3, 7 und 14 Tage nach der Behandlung bestätigte Aufnahme und Translokation nach 3 Tagen, danach konstante Werte. Die Wiederfindung der Radioaktivität war unvollständig, besonders bei Kurztag-Pflanzen, bei denen nachweislich Radioaktivität über das Wurzelsystem verlorenging. Die Änderung der Photoperiode beeinflußte Aufnahme und Translokation nicht; das Verhalten wird wohl durch die Pflanzengröße und Phänologie mehr als von der Photoperiode bestimmt. Der Anteil radioaktiven Materials, das in der Pflanze von den behandelten Blättern verlagert wurde und in der Pflanze bleib (d.h. nicht über die Wurzeln ausgeschieden wurde), war in Kurztag-Pflanzen signifikant geringer als in Langtag-Pflanzen; in Freilandpflanzen wurde am meisten transloziert und in die Rhizome eingelagert. Nur in Kurztag-Pflanzen, wo die Translokation am geringsten, die Pflanzen aber klein waren, wurde eine wirksame Glyphosat-Konzentration erreicht.     

喷施槲皮素对入侵植物空心莲子草根系生长的影响

在入侵植物空心莲子草[Alternanthera philoxeroides (Mart.) Griseb]宿根膨大前期、膨大期和膨大后期,分别喷施20μmol/L和100μmol/L槲皮素,研究槲皮素对空心莲子草根系生长的影响。与对照（CK）相比,2种浓度的槲皮素处理均显著降低了空心莲子草根系活力（P<0.05）、根干重（P<0.05）、地上部分干重（P<0.05）。在空心莲子草根膨大前期喷100μmol/L槲皮素后15 d,膨大期喷20μmol/L槲皮素后15 d,膨大后期喷20μmol/L、100μmol/L槲皮素后10 d,喷100μmol/L槲皮素后15 d几种情况下,空心莲子草根直径显著降低（P<0.05）。这表明,喷施槲皮素可在一定程度上抑制空心莲子草的根系生长,在空心莲子草宿根膨大的不同时期,喷施一定浓度的槲皮素能显著抑制其宿根的膨大生长。     

Distribution of 14C-glyphosate in legumes parasitised by Orobanche crenata

Absorption and translocation of ¹⁴C-glyphosate was evaluated under controlled conditions in peas ( Pisum sativum L.) and broad beans ( Vicia faba L.) parasitised or not by crenate broomrape Orobanche crenata Forsk.). Absorption increased with time up to 12 days after treatment, and reached about 50% of the ¹⁴C-glyphosate applied. Three days after treatment 70–85% of the total herbicide absorbed had been translocated out of the treated leaflet. There was no consistent differ ence in absorption and translocation between infected and non-infected plants 12 days after treatment. The ¹⁴C-glyphosate concentration in the root system increased with time in broad beans. In peas it remained more or less constant from 3 days after treatment. Generally, pods were stronger sinks for glyphosate than other parts of the plant. Herbicide accumulation in broomrape increased with its growth stage, and the parasite was a much stronger sink for glyphosate than the legume root system.     

14C-glyphosate absorption and translocation in germinating maize (Zea mays) and soybean (Glycine max) seeds and in soybean plants

¹⁴C-glyphosate (N-(phosphonomethyl)glycine) uptake by germinating maize (Zea mays L. ‘PAG SX56’) or soybean (Glycine max (L.) Merr. ‘Williams’) seeds from sterile quartz sand was minimal on a weight basis until the radicle became functional. Uptake in soybean seedlings was ten times greater (on a weight basis) than in maize. Germination of either species was not affected by glyphosate concentrations up to 10^?3m , but seedling axis elongation was inhibited in soybeans at 10^?4m and in maize at [0^?3m When ¹⁴C-glyphosate was applied to the fully expanded first trifoliolate soybean leaf (assimilate-exporting), movement into root and shoot assimilate sinks occurred. About 7% of the total ¹⁴C-glyphosate applied was absorbed and translocated into other parts of the plant by 48 h. Of the total ¹⁴C accumulated by 48 h in the roots and apical meristem, nearly 50% was present by 12 h. Minor phytotoxicity resulted from 10 nmoles of glyphosate in the plant. Absorption et migration du ¹⁴ C-glyphosate chez le maïs (Zea mays) en germination et chez les semences et les plantes de soja (Glycine max) L'absorption du ¹⁴C-glyphosate (N-(phosphonométhyle) glycine)par du maïs en germination (Zea mays L.,‘PAG SX56′)ou par des semences de soja (Glycine max (L.) Merr.,‘Williams’) a partir de sable de quartz stérile a été minimale (sur la base du poids) jusquà ce que la racine devienne fonctionnelle. L'absorption par des plantules de soja a été, sur la base due poids, 10 fois plus grande que chez le maïs. La germination de ces deux espèn n'a pas été affectée par des concentrations de glyphosate allant jusquà 10^?3m , maïs l'élongation des plantules a été inhibée chez le soja á 10^?4m et chez le maïs à 10^?3m . Lorsque le ¹⁴C-glyphosate a été appliqué sur la première feuille trifoliée de soja pleinement dévdoppé (en état d'exporter des métabolites). une diminution du mouvemem des métabolites vers les jeunes pousses et vers les racines s'est manifestée. Eaviron 7% du ¹⁴C-glyphosate total appliqué a été absorbé et a migré dans d'autres parties de la plume en 48 heures. Près de 50% du ¹⁴C total accumulé dans les racines et le méristème apical y était présent en 12 heures. Une faible toxicité a réulté de b présence de 10 nmoles de glyphosate dans la plante. ¹⁴ C-glyphosat-Aufnahme und -Translokation bei keimenden Samen von Mais (Zea mays) und Sojabohnen (Glycine max) und bei Sojabohnenpflanzen Die Aufnahme von ¹⁴C-Glyphosat (N-(Phosphonomethyl)glycin) aus sterilem Quarszsand durch keimende Samen von Mais (Zea mays L.‘PAG SX56′) und Sojabohnen (glycine max (L.) Merr.‘Williams’) war, bezogen auf das Pflanzengewicht, bis zur Funktionsaufnahme der Keimwurzel, gering. Die Aufnahme war bei den Sojabohnenkeimlingen zehnmal grösser (Gewichts-basis) als bei Mais. Die Keimung wurde bei beiden Arten durch Glyphosat bis zu 10^?3m nicht beeinflusst. Das Streckungswachstum des Stengels wurde aber bei der Sojabohne bei 10^?4m und beim Mais bei 10^?3m gehemmt. Wenn ¹⁴C-Glyphosat auf das erste vollstándig entwickelte dreibláttrige Sojabohnenblatt (Assimilate exportierend) appliziert wurde, konnte ein Transport in die Assimilatesinks der Wurzel und des Sprosses beobachtet werden. Nach 48 h waren etwa 7% des applizierten ¹⁴C-Glyphosats aufgenommen und in andere Teile der Pflanze transloziert. Vom gesamten nach 48 h in den Wurzeln und im apikalen Meristem akkumulierten ¹⁴C waren fast 50% bereits nach 12 h vorhanden. 10 nmol Glyphosat in den Pflanzen waren nur geringfügig phytntoxisch.     

Effects of two surfactant series on the absorption and translocation of 14C-glyphosate in sicklepod and prickly sida

The weed species, prickly sida (Sida spinosa L.) and sicklepod (Senna obtusifolia L.), were treated with ¹⁴C-glyphosate alone and formulated with different polyethlylane oxide (PEO) surfactants in tallow amine ethoxylate and non-ionic alkoxylate series to determine the amount of ¹⁴C-glyphosate absorption and translocation. The surface tension, contact angle, and ¹⁴C-glyphosate distribution were significantly affected by both the presence of different waxes on the plants and by the addition of surfactants to the glyphosate. The surface and contact angle values of the surfactants, with and without glyphosate, showed a significant increase as the PEO number increased in both surfactant series. A higher absorption of the ¹⁴C-glyphosate was recorded for S. spinosa compared with S. obtusifolia. The absorption and translocation of the ¹⁴C-glyphosate increased with the increase in the PEO number of tallow amine ethoxylate. In the case of the non-ionic alkoxylate surfactant series, an increase in the absorption of ¹⁴C-glyphosate was recorded when the surface tension and contact angle values decreased. There was no significant difference in the translocation values obtained in the two species after the addition of the surfactants. The amount of ¹⁴C-glyphosate absorbed by the treated leaf was significantly higher in the case of S. spinosa compared with S. obtusifolia. A linear relationship was observed with the physical properties, ¹⁴C absorption, and the efficacy of glyphosate with the addition of the non-ionic alkoxylate surfactant series. The percentage control was higher with the higher PEO surfactant in the tallow amine ethoxylate surfactant series and with the lower PEO surfactant in the non-ionic alkoxylate surfactant series as the two series are chemically different.     

Translocation of 14C-glyphosate in johnsongrass (Sorghum halepense L. Pers.) as affected by growth stage and rhizome length

Studies were conducted in the green house on ¹⁴C-methyllabelled glyphosate translocation in johnsongrass as affected by rhizome length and growth stage. The amount of ¹⁴C measured by the liquid scintillation technique in the rhizomes (2-8%) increased with rhizome length (10, 20 or 30 cm) and tended to increase with growth stage (15-30 cm tall, 45-60 cm tall, or at seedhead), but the amount of ¹⁴C per g fresh rhizome weight was almost similar in all cases. Of the total amount applied per plant (0·2 μCi) about 1/3 or less remained on the treated leaf area, while another 1/3 was a absorbed into the treated leaves. Autoradiographs showed that the ¹⁴C label moved to all plant parts, basipetally and acropetally. Migration du glyphosate ¹⁴ C chez le sorgho d'Alep (Sorghum halepense L. Pers.) en relation avec le stage de croissance et la longueur du rhizome Des recherches ont été effectuées en serru sur la migration du glyphosate marqué au ¹⁴C sur le méthyle, chez le sorgho d'Alep, en relation avec la longueur du rhizome et le stade de croissance. La quantité de ¹⁴C mesurée par la technique de scintillation liquide dans les rhizomes (2 à 8%) s'est accrue avec la longueur du rhizome (10, 20 ou 30 cm) et elle a eu tendance à augmenter avec le stade de croissance (Hauteur 15-30 cm, hauteur 45-60 cm ou épiaison), mais la quantité de ¹⁴C par gramme de poids frais de rhizome est restée Presque identique dans tous les cas. Environ 1/3, ou moins, de la quantitéà la surface des feuilles traitées par plante (0,2 μCi), est restéà la surface des feuilles traitées cependant qu'un autre 1/3 a été absorbé dans less feuilles traitées Les autoradiographies ont montré que le ¹⁴C marqueur a migré dans toutes les parties de la plante, dans le sens basipète et dans le sens acropète. Translokation von ¹⁴C-Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge Im Gewächshaus wurden Versuche über die Translokation von ¹⁴C-Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge durchgeführt. An den Rhizomen stieg der Gehalt von ¹⁴C(2–8%), gemessen mit der Flüssig-Szintillationstechnik, mit zunehmender Rhizomlänge (10, 20 oder 30 cm) an und nahm tendenziell auch mit fortschreitendem Pflanzenwachstum zu (15–30 cm und 45–60 cm Sprosslänge oder nach dem Rispenschieben); jedoch blieb die Menge pro g Rhizomfrischgewicht beinahe konstant. Von der insgesamt ausgebrachten Menge pro Pflanze (0.2 μCi) blieben bis zu 1/3 auf der behandelten Blättern absorbiert wurde. Die Autoradiographie zeigte, dass der ¹⁴C markierte Teil in alle Pflanzenteile sowohl basipetal wie auch akropetal transportiert wurde.     

Absorption and translocation of 14C-3,6-dichloropicolinic acid in Cirsium arvense (L.) Scop.

Experiments were conducted in a growth cabinet to investigate the absorption and translocation of ¹⁴C-3, 6-dichloropicolinic acid by Cirsium arvense (L.) Scop. (Canada thistle, creeping thistle), a sensitive species. Applications were made, either to the middle four leaves of 12-cm-tall vegetative plants grown under low (40%) and/or high (>95%) relative humidity (r.h.), or to four upper or lower leaves of 30-cm-tall flowering plants grown under low r.h. Following application to vegetative plants, absorption and translocation of ¹⁴C-3,6-dichloropicolinic acid was rapid and was approximately doubled by high r.h. High r.h. increased the amount of radioactivity retained by the treated leaves or translocated to the shoots but did not affect greatly the amount retained in the roots. The herbicide was highly mobile, with over half of that absorbed, translocated out of the treated leaves after two days. The apex accumulated most of the radioactivity, while approximately 8% was recovered from the roots. The absorption and translocation patterns were similar to those reported in the literature for picloram in C. arvense. Absorption of 3,6-dichloropicolinic acid was greater in vegetative than in flowering C. arvense plants, and placement of herbicide on lower leaves tended to decrease the amount of radioactivity recovered from shoot apex and increase the amount recovered from the roots. Approximately 15% of the applied radioactivity could not be recovered from treated plants by 2 days after treatment.     

The uptake and translocation of 14C-SAN-6706 and 14C-SAN-9789 in Vaccinium macrocarpon cv. Early Black

The uptake and translocation of ¹⁴C-labelled 4-chloro-5-(dimethytamino)-2-(α,α,α,-trifluoro-m-lolyl)-3(2H)-pyridazinone (SAN-6706) and 4-chloro-5-(melhylamino)-2-(α,α,α,-trifluoro-m-tolyt)-3(2H)-pyridazinone (SAN-9789) were studied in cranberry plants (Vaccinium macrocarpon Ait. cv. EarlyBlack). The plants were treated in water solution and sampled at 1,3,8 and 15 days. Other plants were treated for these times, washed free from extraneous herbicide, grown for 3 weeks longer in nutrient with no herbicide and then sampled to determine the fate of the herbicide. Both compounds were readily translocated and the amount of label present in the shoot increased with time. In plants grown for 3 more weeks after treatment there was translocation of the label from the root to the shoot. No radioactive label was detected in the cranberry fruit. Absorption et migration du ¹⁴C-SAN-6706 et du ¹⁴C-SAN-9789 chezVaccinium macrocarpon cv. Early Black L'absorption et la migration de la 4-chloro-5-(dimeAthyiamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone (SAN-6706) et de la 4-chloro-5-(méthylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H) pyridazinone (SAN 9789), marquées au ¹⁴C, ont été eAtudiées chez la canneberge (Vaccinium macrocarponAit, cv. Early Black). Les plantes ont été traitées en solution aqueuse et échantillonnfées aprés 1, 3, 8 et 15 jours. D'autres plantes ont éteA traitées pour ces mêmes durées, Iavées pour éliminer les traces externes d'herbicide, et cultivées pendant 3 semaines de plus en milieu nutritif sans herbicide, et enfin échantillonnées pour determiner le devenir de L'herbicide. Les deux composes migrerent rapldement et la quantité de produit marqué présente dans la partie adrienne augmenta avec le temps. Dans les plantes cultivées 3 semaines supplémentaires aprés le traitement, il y eut migration du produit marque des racines vers les tiges. Aucun élément radioactif n'a été décelé dans les fruits de canneberge. Die Aufnahme und Translokatlon von ¹⁴C-SAN-6706 und¹⁴CSAN-9789 bei Vaccinium macrocarpon Sorte Early Black Es wurde die Aufnahme und Translokation von ¹⁴C-markiertem 4-Chlor-5-(dlmcthylamino)-2-(α,α,α;-trifluor-m-tolyl)-3(2H)-pyridazinon (SAN-6706) und 4-Chlor-5-(methylamino)-2-(α,α,α-trifluor-m-tolyl)-3(2H)-pyridazinon (SAN-9789) bei Preiselbeerpflanzen (Vaccinium macrocarpon Ait. Sorte Early Black) untersucht. Die Pflanzen wurden in Wasserkultur behandelt und nach 1, 3, 8 und 15 Tagen Proben genommen. Bei anderen Pflanzen, die auch über diese Perioden behandelt worden waren, wurde anschliessend das äuβerlich anhaftende Herbizid abgewaschen, für 3 weitere Wochen in NaUhrlösung ohnc Herbizid gehalten und dann Proben gezogen, um die Verteilung des Herbizids zu bestimmen. Beide Verbindungen wurden rasch transloziert und der Gehait an markierter Substanz im Spross nahm mit der Zeit zu, in den Pflanzen die für 3 weitere Wochen nach der Behandlung gewachsen waren, wurde Translokation voti der Wurzel in den Spross festgestellt. In der Preiselbeerfrucht konnte keine Radioaktivität festgestellt werden.     

Formulation and adjuvant effects on the absorption and translocation of 14C-clethodim in wheat (Triticum aestivum L.)

A new formulation of clethodim {(E,E)-(±)-2-(1-[([3-chloro-2-propenyl]oxy)imino]propyl)-5-(2-[ethylthio]propyl)-3-hydroxy-2-cyclohexen-1-one} is labeled for the control of grasses and volunteer grass crops, including glyphosate-resistant corn. The effects of the formulation (new: 0.12 kg L⁻¹ and current: 0.24 kg L⁻¹) and adjuvants (ammonium sulfate [AMS], crop oil concentrate [COC] or both) on the absorption and translocation of the ¹⁴C-clethodim was determined at 1, 4, 12, 24, 48, and 72 h after treatment (HAT) in wheat under greenhouse conditions. The absorption of the ¹⁴C-clethodim with the 0.12 kg L⁻¹ formulation was higher than that with the 0.24 kg L⁻¹ formulation, especially at 24 HAT and beyond, regardless of the presence or absence of an adjuvant. The addition of an adjuvant increased the absorption of the ¹⁴C-clethodim with the 0.12 kg L⁻¹ formulation at all harvest times, except at 72 HAT. However, there were no differences in the ¹⁴C-clethodim absorption among the adjuvants added to the 0.12 kg L⁻¹ formulation, except at 48 and 72 HAT. Most of the ¹⁴C-clethodim remained in the treated leaf independent of the formulation or adjuvant. The formulation did not have an impact on the distribution of the absorbed ¹⁴C-clethodim; however, the presence of an adjuvant increased the movement of the ¹⁴C-clethodim out of the treated leaf. Most of the absorbed ¹⁴C-clethodim remained in the treated leaf and a negligible amount translocated to the root. These results demonstrated the improved absorption of clethodim with a formulation containing half of the active ingredient (0.12 kg L⁻¹) and the inclusion of both AMS and COC.     

Metabolism, uptake and translocation of 14C-paraquat in resistant and susceptible biotypes of Crassocephalum crepidioides (Benth.) S. Moore

The metabolism, uptake and translocation of paraquat in resistant (R) and susceptible (S) biotypes of Crassocephalum crepidioides (Benth.) S. Moore (redflower ragleaf) at the 10-leaf stage was investigated. A study on the properties of leaf surface was carried out to examine the relationship between leaf surface characters and paraquat absorption. The extractable paraquat was not metabolized by the leaf tissue of either the resistant or susceptible biotypes. Differential metabolism, therefore, does not appear to play a role in the mechanism of resistance. Both biotypes did not show any significant difference in the amount of cuticle and trichome densities. Furthermore, both biotypes are identical in the structure of stomata, trichomes and epicuticular wax. The results of the leaf surface studies are in agreement with the findings of the uptake study. Both biotypes demonstrated no significant difference in absorption between the resistant and susceptible biotypes. However, 10% of the absorbed ¹⁴C-paraquat into the S biotype was translocated basipetally, but not in the R biotype. The results of this study suggest that in C. crepidioides , differential translocation may contribute to the mechanism of resistance at the 10-leaf stage.     

Studies on the mode of action of asulam in bracken (Pteridium aquilinum L. Kuhn) I. Absorption and translocation of [14C]asulam

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.     

PRELIMINARY STUDIES ON THE TRANSLOCATION OF 14C-LABELLED HERBICIDES IN BRACKEN (PTERIDIUM AQUILINUM)

Summary. The translocation of ¹⁴C-labelled herbieides in field bracken has been sludied in some preliminary experiments by means of autoradiography. A detailed account is given of the methods employed. It is shown that when 2,4-D is applied to fronds at different stages of development movement of the tracer into the rhizome is considerably greater from parts of the frond which are still immature. Trasnslocation within the frond is predominantly basipetal at all stages of development; within the rhizome the direction of movement appears to be determined primarily by the nature of the vascular connections with the treated pinna.
In a comparison between the translocation of 2,4-D, 4-CPA and dalapon no difference was apparent after 24 hours, but when the treatment period was extended to 96 hours there was evidence that 4-CPA bad been translocated in a considerably greater amount than either of the other two herbicides.
Rechrches iréliminaires sur la migration des herbieides marqués am ¹⁴ C dans la fougrère algle (Pteridium aquilinum)     

Bound and extractable 14C residues in canola (Brassica napus) plants treated with radiolabelled atrazine

The nature and distribution of ¹⁴C atrazine (2- chloro- 4 -ethylamino- 6 -isopropylamino-s-tria- zine) residues in resistant and susceptible canola (Brassica napus L.) varieties were studied. Radiolabelled atrazine was applied to the plants just before the flowering stage and continued for 10 days. The plants were harvested 3, 10 and 25 days after the end of the treatment. The roots, shoots and pods of each plant were exhaustively extracted with methanol. The ¹⁴C distribution between the methanol extracts and the plant matrix fractions (bound residues) was similar for the two varieties. High-pressure liquid Chromatographie analysis of the methanol extracts showed that they contained two unknown metabolites (possibly conjugates) in addition to atrazine. The bound ¹⁴C residues were released by supercritical methanol extraction and analysed by thin-layer chromato- graphy, gas chromatography and high-pressure liquid chromatography. Several ¹⁴C components in the released material were detected. Bound atrazine and its two dealkylated metabolites represented only a very small portion (10–18%) of the total bound ¹⁴C residues in the plants. Résidus ¹⁴C extractibles et liés chez des plantes de canola (Brassica napus) traitées avec de l'atrazine radioactivement marquée La nature et la distribution de résidus d'atrazine ¹⁴C (2-chloro 4-ethylamino-6-isopropylamino-s-triazine) chez des variétés de canola résistantes et sensibles ont étéétudiés. De l'atrazine radiomarquée a été appliquée aux plantes juste avant la floraison et poursuivie pendant 10 jours. Les plantes ont été récoltées 3, 10 et 25 jours après la fin du traitement. Les racines, tiges et gousses de chaque plante ont été complètement extractées avec du methanol. La distribution du ¹⁴C entre les extraits méthanol et les fractions de plantes matricielles (liées) a été similaire pour les 2 variétés. Des analyses HPLC des extraits méthanol ont montré qu'ils contenaient deux metabolites inconnus (probablement combinés) en plus de l'atrazine. Les résidus ¹⁴C liés étaient libérés par une extraction au méthanol supercritique et analysé par Chromatographie en couche mince, Chromatographie gazeuze et HPLC. Plusieurs composés dans le matériel libéré ont été détectés. L'atrazine liée et ses deux metabolites dealklyés représentaient seulement une très petite part (10–18%) de la totalité des résidus ¹⁴C liés dans les plantes. Gebundene und extrahierbare ¹⁴C-Rückstände in mit radioaktiv markiertem Atrazin behandeltem Raps (Brassica napus) Die Art und die Verteilung von Rückständen von ¹⁴C-Atrazin (2-Chlor-4-ethylamin-6-iso- propylamin-s-triazin) wurden in resistenten und empfindlichen Varietäten von Raps (Brassica napus) untersucht. Das radioaktiv markierte Herbizid wurde kurz vor der Blüte und 10 Tage weiter auf die Pflanzen ausgebracht. Die Pflanzenproben wurden 3, 10 und 25 Tage nach dem Ende der Behandlung gezogen. Wurzeln, Sprosse und Schoten wurden erschöpfend mit Methanol extrahiert. Die ¹⁴C-Verteilung in den Methanolextrakten und im Pflanzenmaterial (gebundene Rückstände) war bei beiden Sorten ähnlich. Bei der HPLC-Analyse wurden in den Methanolextrakten neben Atrazin 2 unbekannte Metaboliten (vermutlich Konjugate) gefunden. Die gebundenen ¹⁴C-Rückstände wurden im Überkritischen Verfahren mit Methanol extrahiert und dünnschicht-, gas-und HPL-chromatographisch analysiert. Verschiedene ¹⁴C-Verbindungen wurden gefunden. Gebundenes Atrazin und seine beiden de-alkylierten Metaboliten machten nur eine kleinen Anteil (10 bis 18%) der gesamten gebundenen ¹⁴C-Rückstände aus.     

Protection of Vineyards from Grey Mould in Georgia (USSR)1

Grey mould is a very serious disease under the subtropical conditions of Georgia. While cultural methods and control of other pests and diseases offer some potential for control, fungicides play an important role and data are presented on the efficacy of several products and mixtures under Georgian conditions.     

Effect of chlorfenprop-methyl, flamprop-isopropyl and benzoylprop-ethyl on 14C2 fixation in Avena fatua L., Triticum aestivum L. and Hordeum vulgare L.

The effect of chlorfenprop-methyl, flampropisopropyl and benzoylprop-ethyl on ¹⁴CO₂ fixation was followed in wild oat (Avena fatua L.), barley (Hordeum vulgare L., cv. Ametyst), and wheat (Triticum aestivum L., cv. Mironovská). Experimental plants were exposed to a ¹⁴CO₂-enriched atmosphere in a special apparatus 2 h, 1, 3, and 9 days after the herbicide treatment. Chlorfenprop-methyl already inhibited ¹⁴CO₂ fixation in wild oat plants 2 h after the treatment. ¹⁴C-metabolite transport to the roots was strongly decreased. Both ¹⁴CO₂ fixation and ¹⁴C-metabolite level in the roots were significantly depressed in A. fatua when compared with untreated plants at the last sampling time. ¹⁴C incorporation into starch was inhibited from the first day after treatment, and on day 9 was lowered more than ten fold in treated plants. Flamprop-isopropyl inhibited ¹⁴CO₂ fixation in wild oat plants from day 3 after treatment, but benzoylprop-ethyl not until day 9. Both herbicides also decreased ¹⁴C incorporation into starch in A. fatua. Chlorfenprop-methyl also slightly decreased ¹⁴CO₂ fixation in barley on day 9. However, assimilate transport into the roots and ¹⁴C incorporation into starch were not affected. Flamprop-isopropyl inhibited ¹⁴CO₂ fixation in barley plants only on the first day after treatment, and assimilate transport was also reduced. By contrast, no differences from untreated plants were found at the end of the experiment. Benzoylprop-ethyl did not decrease either ¹⁴CO2 fixation or assimilate transport to the roots in wheat, but it inhibited starch synthesis. Atrazine depressed ¹⁴CO₂ fixation in wild oat plants by 91%, in wheat plants by 99% compared with untreated plants. Assimilate transport into the roots was also strongly inhibited. In contrast to atrazine, the effect of chlorfenprop-methyl, flamprop-isopropyl, and benzoylprop-ethyl on CO₂ fixation seems to be secondary.     

Chemical Control of Botrytis cinerea on Grapes in New York (USA)1

Control of gray mold in New York vineyards is difficult to achieve at the present time. Benomyl-resistant strains of Botrytis cinerea have been isolated from vineyards in all grape-growing regions of New York State. Because of this resistance and lack of governmental registration of new fungicides, growers must choose among only moderately effective fungicides such as captan, folpet, dicloran and copper. Current research indicates that either vinclozolin or iprodione at 850 g/ha to 1100 g/ha applied twice, beginning at about 5 % sugar content and two weeks later, will provide excellent control of gray mold on ripening berries, whereas sprays applied at 5 % or 90 % bloom and at berry touch are not effective. An application of gibberellic acid (GA3) (10 or 25 (µg/ml) on Aurore (S.5279) at 10–15 cm shoot growth reduced the severity of gray mold on clusters of ripe fruit, but not the incidence of it. A single application of triadimefon at 30 mg/1 sprayed on Vignoles (Ravat 51), when fruit clusters averaged 17 % surface area infected with Uncinula necator and 2.6 % sugar content, retarded the development of powdery mildew and subsequent berry splitting, and ultimately reduced the severity of gray mold by 50 % at harvest, 6 weeks later.     

Some Aspects of New Technology for Protection of Field Crops in Poland (Machinery and Techniques)1

The Institute for Plant Protection at Poznan (Poland) examines the biological efficacy of new plant protection equipment or techniques. Examples of recent studies include: 1) a sprayer with a lateral reach of up to 40 m under favourable conditions, which has been successfully used on crops liable to mechanical damage from traditional tractor sprayers (oilseed rape at flowering, field bean, seed crops of sugar beet and onion, sunflower, maize); 2)equipment for spraying potatoes against Thanatephorus cucumeris at the time of planting; 3) use of passage-ways for sprayers in cereal crops, results having shown that spraying from passage-ways gives better biological results and that adjoining plants compensate the losses due to absence of plants in the passage-ways.