The advantage of tbz + iprodione treatment for control of gray mold decay of celery caused by the heterogenic spore population ofBotrytis cinerea in Israel

A combined TBZ — iprodione treatment was more effective in inhibiting growthin vitro ofBotrytis cinerea isolates obtained from decayed celery than either of the fungicides applied separately. This was exhibited for both TBZ-resistant and TBZ-sensitive isolates. TBZ at 500 (μg ml^-1 plus iprodione at 1000 μg ml^-1 reduced celery decay beyond the reduction obtained by each fungicide alone. When applied prior to inoculation, the combined treatment prevented decay by the TBZ-sensitive/iprodione-resistant isolates and reduced initial decay by the TBZ-resistant/iprodione-sensitive isolates to 3–10% of the level without treatment. Under natural infection conditions iprodione showed better decay control than TBZ, and at 1500 μg ml^-1 it reduced initial decay during prolonged storage to 3% of the no-treatment level. Although TBZ (500 μg ml^-1) or iprodione (1000 μg ml^-1) applied separately reduced decay significantly, the combination of lower concentrations of each fungicide was sufficient to eliminate decay development almost totally. The combined treatment also inhibited decay bySclerotinia sclerotiorum, which contributed 3% of the total soft rot in stored celery.     

An analytical procedure for bromoxynil and its octanoate in soils; persistence studies with bromoxynil octanoate in combination with other herbicides in soil

A method is described for the analysis of the herbicide bromoxynil and its octanoate in soils. Following extraction with aqueous acidic acetonitrile, the octanoate was separated from the phenolic bromoxynil by solvent partitioning. The ester and the phenol were assayed by gas-liquid chromatography without further modification or preparation of a derivative. Recoveries in excess of 93% were obtained from soils treated with the phenol and the ester at levels of 0.5 or 0.1 μg g^?1. The persistence of bromoxynil octanoate applied at a rate of 3 μg g^?1 was studied in the laboratory on a heavy clay and a sandy loam at 85% of field capacity moisture and 20°1°C, both alone and in the presence of 2,4-D (2 μg g^?1); MCPA (2 μg g^?1); MCPA+asulam (both at 2 μg g^?1); and MCPA+difenzoquat (both at 2 μg g^?1). In each soil there was a rapid conversion of bromoxynil octanoate to the free phenol, which then underwent a rapid degradation, so that after 7 days, over 90% of the original treatment had disappeared. There appeared to be no effect on bromoxynil breakdown by any of the herbicides added in combination. Small field plots were treated, in early May 1977 and 1978 at two locations in Saskatchewan, with a combination of commercial formulations containing asulam, bromoxynil octanoate, and MCPA at rates of 1 kg ha^?1 each. After 10 weeks the plots were sampled and analysis showed that in all cases, no asulam, bromoxynil, or bromoxynil octanoate could be extracted from the top 10 cm of soil.     

Chlorpyrifos degradation in soil at termiticidal application rates

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha^?1) result in initial soil surface residues of 0.3 to 32 μg g^?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g^?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [¹⁴C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g^?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [¹⁴C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g^?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g^?1 rate as compared to the 10 μg g^?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC ₅₀ = 0.2– 2 μg g^?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.     

Efficacy of metalaxyl for blue mould control and its persistence on tobacco

Foliar sprays of metalaxyl, benalaxyl, and cymoxanil plus mancozeb gave better control of blue mould (Peronospora tabacina) than mancozeb alone applied as a spray, or metalaxyl applied to the soil. Before flue-curing, the mean values of metalaxyl residues in tobacco leaves were significantly higher from foliar spray treatments (5.09 μg g⁻¹), than from soil treatments (0.93 μg g⁻¹). Residues had decreased after flue-curing (foliar spray treatment 2.51 μg g⁻¹; soil treatment 0.69 μg g⁻¹), especially on samples taken in September. Curing considerably reduced metalaxyl residues in all cases. Residues of mancozeb ranged from 59.5 to 224.2 μg g⁻¹ before flue-curing and from 11.0 to 22.1 μg g⁻¹ after flue-curing. All these residues were calculated on a dry weight basis. Imidazolidine-2-thione (ethylenethiourea) residues from mancozeb were always below the sensitivity limit of the method used.     

Pesticide residues in foodstuffs in England and Wales. Part II: Inorganic bromide ion in cucumber,tomato and self-blanching celery grown in soil fumigated with bromomethane,and the ‘natural’ bromide ion content in a range of fresh fruit and vegetables

Surveys of inorganic bromide ion residues in tomatoes, cucumbers and selfblanching celery, commercially produced in England following soil sterilisation with bromomethane, have been carried out since 1979. The mean bromide ion level in 29 late-season cucumber samples was approximately 28 mg kg⁻¹ and ranged up to 109 mg kg⁻¹. Analysis of 242 tomato samples gave estimated mean bromide ion levels per plant ranging from 6 to 187 mg kg⁻¹ in fruit picked throughout the season from seven holdings, on six of which bromomethane had been used fairly recently prior to planting. A statistically significant fall in bromide levels over the growing season was shown on four of the sites. In 38 samples of self-blanching celery, the mean bromide ion level was 104 mg kg⁻¹ even though the mean interval between fumigation and planting was in excess of 1 year. Retail surveillance indicated that a large number of crops are likely to have bromide ion levels below 10mg kg⁻¹.     

Effects of the experimental fungicide RH 886 on Mucor piriformis

No registered fungicide controls Mucor piriformis, a cause of severe postharvest storage rot in pears, but the experimental fungicide RH 886 (active ingredients: 77% 5-chloro-2-methylisothiazol-3-(2H)-one and 23% 2-methylisothiazol-3-(2H)-one) has an ED₅₀ of 23.1 μg ml^?1 in 5 min exposure for germination of sporangiospores of M. piriformis and an ED₅₀ of 9.9 μg ml^?1 for mycelial growth. Mixing RH 886 into infested, amended soil at 8 mg g^?1 soil or mixing copper sulfate into soil at 1 mg g^?1 soil prevented sporulation of M. piriformis. Application of RH 886 to pear fruits prior to inoculation, or immersion of fruits in solutions of RH 886 containing sporangiospores of M. piriformis significantly reduced fruit infection.     

Excretion and residues of the pyrethroid insecticide cypermethrin in lactating cows

Two radiolabelled forms of racemic [¹⁴C]cypermethrin (¹⁴C at the benzylic carbon or at C-1 of the cyclopropane ring) were separately administered twice daily to lactating cows in portions of the feed. The amounts dosed were equivalent to 0.2, 5 and 10 μg of cypermethrin per g of feed. The radioactivity eliminated in the milk indicated that the ingestion and elimination of radioactivity were in balance at about day 4 after the start of dosing. Urine and faeces were equally the major routes of elimination, and only a fraction of a percent of the dose appeared in the milk. The residue in the milk was unchanged cypermethrin and was found at a concentration that was proportional to the dose. At the high cypermethrin intake of 10 μg g^?1 of diet, the residue in the milk was 0.03 μg g^?1. Concentrations of residues in the tissues, measured after 7, 20 or 21 days of treatment, were low and in the order: liver>kidney>renal fat>subcutaneous fat>blood>muscle>brain. The major residue in the liver and kidney of a cow that received 10 μg of cypermethrin per g of diet was N-(3-phenoxybenzoyl)glutamic acid. Other conjugates of 3-phenoxybenzoic acid and of 3-(4-hydroxyphenoxy)benzoic acid (unidentified, with the exception of the glycine conjugate) were also present. The residue in fat (about 0.1 μg g^?1 from an intake of 10 μg g^?1 of feed) consisted mainly of cypermethrin.     

Root exudation of prometryn and its metabolites from Chinese celery (Apium graveolens)

Root exudates from Chinese celery (Apium graveolens) and Chinese cabbage (pak choi, Brassica chinensis) plants treated by prometryn, an herbicide, were qualitatively and quantitatively investigated and compared under hydroponic cultivation. Prometryn and its metabolites released into the nutrient solution were analyzed by ultra-performance liquid chromatograph coupled with orbitrap mass spectrometer to investigate whether this xylem-mobile herbicide is exuded from the roots. The results showed that celery and pak choi had different root exudation profiles. Celery metabolized prometryn to prometryn sulfoxide and released both compounds from the roots. In contrast, pak choi barely metabolized or actively released prometryn from the roots. The concentration of prometryn sulfoxide released from celery after 96 hr was 21 µg/L, which was nearly one-third that of released prometryn. Our results indicate that the root exudation and translocation of xylem-mobile herbicides could be significant in plants and are highly species dependent compared with phloem-mobile herbicides.     

苯醚甲环唑在芹菜和土壤中的残留行为及风险评估

在湖南和山东开展了10%苯醚甲环唑水分散粒剂在芹菜上的残留田间试验,在室内进行了土壤生物的急性毒性试验。基于苯醚甲环唑的残留试验数据和毒性端点值,就苯醚甲环唑对中国不同人群的长期及短期膳食摄入风险和对土壤生物的环境风险进行了评估。结果表明：苯醚甲环唑在芹菜叶、茎和土壤中的消解半衰期分别为5.2～8.8 d、8.0～8.2 d和13.6～15.0 d。苯醚甲环唑按推荐剂量有效成分120 g/hm²喷雾施药3次,施药间隔期5 d,距最后一次施药5 d收获时苯醚甲环唑在芹菜叶片中的残留量高于MRL (3 mg/kg,中国),在茎和整株芹菜中的残留量均低于MRL。普通人群和1～6岁儿童的短期摄入风险商(RQ_a)值分别为0.09和0.10;对于不同人群,芹菜中苯醚甲环唑对长期膳食摄入风险商的贡献率(RQ_c%)为9.4%～19.8%。10%苯醚甲环唑水分散粒剂对环境中的土壤生物风险商(RQ_e)值为0.368～0.890,不会产生初级急性风险。     

Comparative metabolism of atrazine and EPTC in proso millet (Panicum miliaceum L.) and corn

The purpose of this study was to examine the differential activities of proso millet (Panicum miliaceum L.) and corn (Zea mays L.) with respect to atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-S-triazine] and EPTC (S-ethyldipropyl thiocarbamate) metabolism. GSH-S-transferase was isolated from proso millet shoots and roots. When assayed spectrophotometrically using CDNB (1-chloro 2,4-dinitrobenzene) as a substrate, the shoot enzyme had only 10% of the activity of corn shoot enzyme while the root enzyme had 33% the activity of corn root enzyme. However, when proso millet shoot GSH-S-transferase was assayed in vitro using ¹⁴C-ring-labeled atrazine, it degraded the atrazine to water-soluble products at the same rate as the corn shoot enzyme. Incubation of excised proso millet and corn roots with [¹⁴C]EPTC indicated that uptake of EPTC was similar in both plants. However, proso millet metabolized the EPTC to water-soluble products at only half the rate of corn. Glutathione levels of proso millet roots were 35.9 μg GSH/g fresh wt, compared with 65.4 μg GSH/g fresh wt for corn. However, a 2.5-day pretreatment with R-25788 (N,N-diallyl-2-2-dichloroacetamide) elevated proso millet GSH levels to 62.7 μg GSH/g fresh wt. R-25788 did not elevate the activity of proso millet GSH-S-transferase, in contrast to its effects on corn. We conclude that differences in response to atrazine and EPTC in proso millet and corn are a result of their differential metabolism.     

Movement and persistence of [14C]imidacloprid in sugar-beet plants following application to pelleted sugar-beet seed

[¹⁴C]Imidacloprid was applied to pelleted seeds of sugar beet which were then grown in pots of field soil. Leaves, roots and soil were analysed at intervals up to 97 days after planting and the distributions of parent compound and of several metabolites were quantified. At the first sampling, 21 days after application, parent imidacloprid was the main compound found in the leaves and its concentration averaged 15·2 μg g^-1 fresh weight. By the 25-leaf stage, 97 days after sowing, the concentration of parent compound in the leaves had fallen to an average of 0·5 μg g^-1; the metabolites and parent compound in the leaves then represented respectively 44·5% and 4·5% of the total applied radioactivity. In the root at 97 days, parent imidacloprid and its metabolites together accounted for only 0·1% of the applied activity, whilst in the soil there was 23% of parent compound and 4% as metabolites. The persistence of both parent imidacloprid and the olefinic metabolite, which has recently been shown to have higher aphicidal activity than the parent imidacloprid, explains the prolonged control of aphids observed with imidacloprid in both glasshouse and field trials. © 1998 SCI.     

Fungi in stored barley treated with systemic fungicides

Six fungicides (benomyl, carbendazim, fuberidazole, thiabendazole, thiophanate and thiophanate-methyl) were applied as dusts to barley in concentrations of 100, 1000 and 10 000 μg g^?1 and the barley then stored at 20°C and 90% relative humidity for 60, 105 and 150 days, respectively. Fungal development during storage was assessed by counting the visible patches of developing mould and by dilution plating. None of the fungicides completely prevented fungi developing but for the period up to 60 days, all provided a degree of control that was generally greatest for the highest concentration of fungicide. Benomyl was the most effective of the fungicides but no clear pattern was established for the others. Of the fungi that developed, species of Aspergillus and Penicillium accounted for 94% of the total count.     

Uptake,metabolism and effects of DDT,fenitrothion and chlorpyrifos on Tetrahymena pyriformis

The uptake and metabolism of DDT, fenitrothion and chlorpyrifos were studied in cultures of the ciliate protozoan Tetrahymena pyriformis. When cultures were treated with DDT in concentrations varying from 0.01 to 0.5 μg ml⁻¹, concentrations found in T. pyriformis were 3.8 to 335 μg g⁻¹ dry weight. The accumulation of fenitrothion ranged from 28.7 μg g⁻¹ in cultures treated with 1 μg ml⁻¹ to 2260 μg g⁻¹ in cultures treated with 10 μg ml⁻¹. Under similar experimental conditions chlorpyrifos was accumulated from 24.7 to 15400 μg g⁻¹. The patterns of uptake were dependent on the growth cycle, the ability of the organism to metabolise insecticide and the type of the insecticide used. Maximum accumulation of DDT, fenitrothion and chlorpyrifos occurred in 2, 4 and 6 h respectively. Tetrahymena metabolised DDT to DDD and DDE but failed to metabolise fenitrothion and chlorpyrifos. The effects on growth and morphology of T. pyriformis were studied over a period of 5 days. Higher concentrations (10, 50 and 100 μg ml⁻¹) of DDT inhibited only the growth of the organisms and did not change cell morphology. Fenitrothion was extremely toxic to the organisms and at 5 and 10 μg ml⁻¹ cells became more or less spherical and died after 48 h. However, concentrations of 0.5, 1 and 2.5 μg ml⁻¹ fenitrothion caused growth inhibition, but only at 2.5 μg ml⁻¹ was this permanent. Chlorpyrifos inhibited the growth of the organisms at 1, 5 and 10 μg ml⁻¹ but the morphology was affected only at 5 and 10 μg ml⁻¹.     

The effect of asulam on the growth of tissue cultures of celery

The response, of cell suspension and callus cultures of celery to asulim (6–600 μmoll^?1) in the nutrient medium was compared with that of seedlings. The callus cultures were treated.at three slages of differentiation: undifferentiated callus, differentiated callus on which embryoids had developed to the globular and heart-shaped stage, and finally plantlets which had secondary leaves and roots. Cell division in the suspension culture was enhanced at low concentrations (6 and 12 μmoll^?1) and inhibited at higher concentrations Cell expansion was unaffecte by the presence of asulam In differentiated tissue the growth stimulation at low concentrations was absent. and there was a steady decline in accumulation of fresh weight with increasing concentration. Root length and number of laterals of intact seedlings showed a similar pattern, indicating that the response of the tissue to asulam was not radically altered by differentiation     

Quantitative method of inoculation of celery plants withSeptoria apiicola

Celery (Apium graveolens L.) plants were inoculated with 3-µl droplets of a pycnidiospore suspension ofSeptoria apiicola Speg., and then covered with polyethylene bags and kept at an ambient temperature of 23±2°C. Under these conditions disease expression was related to incubation time up to 8 days, and to spore concentrations up to 500/3 µl. An inoculum concentration as low as four viable spores per 3 µl caused 26% as many lesions as did 500 spores/3 µl. In plants not covered, or covered with polyethylene bags for only 1 day, no disease symptoms appeared regardless of the spore concentration applied to the plants. Disease symptoms on inoculated leaves appeared on 10-50-day-old but not on 50-90-day-old leaves. The pathogenicity of 16 isolates collected from two different regions of Israel, and of eight replicates of an isolate used in previous pathogenicity tests, was similar.     

Effects of terbinafine on growth, squalene, and steryl ester content of a celery cell suspension culture

The allylamine terbinafine inhibited growth of a celery (Apium graveolens) cell suspension culture (I₅₀ = 90 μM) and blocked the action of squalene epoxidase, resulting in an accumulation of squalene and a decrease in the sterol content of the cells. Celery cells were tolerant to squalene accumulation; inhibition of growth of cultures was associated with a fall in the free sterol content below about 1 μg sterol/mg dry wt of cells. At Day 14, untreated celery cells contained about 60% of the total sterol in the esterified form. However, the steryl ester pool was considerably lower in terbinafine-treated cells which may reflect an attempt to maintain the free sterol content above a threshold value. The composition of free sterols of terbinafine-treated cells was different from control cultures, suggesting that terbinafine has a second site of inhibition on the pathway to major sterols in plants.     

Comparative testing of several juvenile hormone analogues in two species of locusts,Locusta migratoria migratorioides and Schistocerca gregaria

Effective treatment with juvenile hormone analogues (JHAs) of early penultimate or early last-instar locust hoppers induces a supernumerary ‘extra’ nymphal instar. These ‘extra’ nymphs, also termed ‘adultoids’, die in the course of, or shortly after, an ‘extra’ moult. Less effective treatment results in imperfect adults with crumpled twisted wings which presumably limit their flight and migratory abilities. Extremely effective treatment leads to death in the next moult. Comparing dose-response relations of (7S)-methoprene, fenoxycarb, pyriproxyfen and a new JHA, R70-1 (ethyl cis-N-{2-[4-(2-hydroxycyclohept-1-ylmethyl)phenoxy]ethyl}carbamate), we revealed that route of administration, instar of the recipient hopper, and species may alter over 1000-fold the ED₅₀ for the same JHA. Locusta migratoria migratorioides is much more susceptible to JHAs than Schistocerca gregaria. The lowest ED₅₀ found to induce adultoids and subsequent death in the ‘extra’ moult was 0·12 μg pyriproxyfen injected in olive oil to early penultimate instar hoppers of L. m. migratorioides (about 0·5 μg g^-1 fresh weight). R70-1 was more active than pyriproxyfen following the more practical topical application to early last-instar hoppers of L. m. migratorioides, 5·9 μg and 46 μg per hopper, respectively (about 10 μg g^-1 and 78 μg g^-1 fresh weight). The high susceptibility of last-instar L. m. migratorioides nymphs to topically applied R70-1 is promising from the practical standpoint. ©1997 SCI     

The uptake of metabolites of permethrin by plants grown in soil treated with [14C]permethrin

Sugar beet, wheat, lettuce and cotton were grown in soil treated with [¹⁴C]permethrin, the crops being sown at intervals of 30, 60 and 120 days after treatment of the soil. The uptake of radioactive residues into these crops was measured. Low radioactive residues (up to 0.86 μg g^?1) were detected in the mature plants sown 30 days after soil treatment, and this uptake declined significantly as the interval between soil treatment and sowing increased. Metabolites derived from the acid moiety of the permethrin molecule were shown to constitute the greater part of the residue transferring from the soil to the crops. (1RS)-cis- and (1RS)-trans-3-(2,2-dichlorovinyl)- 2,2-dimethylcyclopropanecarboxylic acid and 3-(2,2-dichlorovinyl)-1-methylcyclopropane-1,2-dicarboxylic acid were identified as the major acidic metabolites. The latter compound is a metabolite of permethrin which has not previously been identified in soil or plants.     

Uptake and translocation of 14C-glyphosate in Alternanthera philoxeroides (Mart.) Griseb. (alligator weed) I. Rhizome concentrations required for inhibition

Rhizome segments from Alternanthera philoxeroides were shaken in solutions of ¹⁴C-glyphosate for 24 h to establish a range of internal tissue concentrations. Rhizomes were killed at concentrations of 16 μg g^?1 dry weight and above and survived at concentrations of 8 μg g^?1 dry weight and below. Plants grown in the field for 10 weeks in declining photoperiod were used to investigate the uptake and translocation of ¹⁴C-glyphosate after application of a constant dosage in either 1.0-or 0.2-μl droplets corresponding to concentrations of 1.06 and 5.3 g 1^?1, of glyphosate acid, respectively. Use of smaller droplets of higher concentration increased absorption of ¹⁴C, but did not improve translocation. Uptake by treated leaves was 25 and 41% of the applied glyphosate for the large and small droplets respectively, but translocation to underground parts of the plant was about 7% of applied ¹⁴C-activity. Radiolabel accumulated in new rhizomes was equivalent to about 0.5 μg g^?1 dry weight of glyphosate, at least 30 times below the concentration required for tissue death. Absorption et transport de glyphosate C14 chez Alternanthera philoxeroides (Mart.) Griseb. I.Concentrations dans les rhizomes nécéssaires pour l'inhibition Des fragments de rhizome d'Alternanthera philoxeroides ont été trempés dans des solutions de glyphosate C14 pour aboutir à un éventail de concentrations internes des tissus, Les rhizomes ont été tués à des concentrations de 16 μg g^?1 PS et plus, et ont survécu à des concentrations de 8 μg g^?1 PS et en-dessous. Des plantes cultivées en plein champ pendant 10 jours en photopériode décroissante ont été utilisées pour étudier l'absorption et le transport du glyphosate C14 après l'application d'une dose constante dans des gouttelettes de 1 ou 0,2 μl correspondant à des concentrations de 1,06 et 5,3 g l^?1 de glyphosate C14 acide respectivement, L'utilisation de gouttelettes plus petites de concentrations plus é1evées a augmenté l'absorption du C14, mais n'en a pas amélioré le transport. L'absorption par les feuilles traitées était de 25 et 41% du glyphosate appliqué pour les grandes et les petites gouttelettes respectivement, mais le transport vers les parties souterraines de la plante était d'environ 7% du C14 appliqué. Le radio-marqueur dans les nouveaux rhizomes était équivalent à environ 0,5 μg g^?1 PS de glyphosate, soit au moins 30 fois en-dessous de la concentration nécessaire à la mort des tissus. Aufnahme und Translokation von ¹⁴C-Glyphosat in Alternanthera philoxeroides (Mart.) Griseb. I. Für die Hemmung erforderliche Konzentration im Rhizom Rhizomteile von Alternanthera philoxeroides wurden 24 Stunden lang in ¹⁴C-Glyphosat-Lösungen geschüttelt, um eine Reihe von Konzentrationen in den inneren Geweben einzustellen. Die Rhizome wurden bei Konzen-trationen von 16 und mehr μg g^?1 TM abgetötet und überlebten bei Konzentrationen von 8 μg g^?1 TM und weniger. Die Aufnahme und Translokation von ¹⁴C-Glyphosat nach der Applikation einer konstanten Dosis in 1,0-oder 0,2-μl-Tröpfchen, entsprechend Konzentrationen von 1,06 und 5,3 g l^?1 Glyphosat-Säure, wurden an Pflanzen untersucht, die im Freiland 10 Wochen lang bei abnehmender Photoperiode gewachsen waren. Der Gebrauch kleinerer Tropfen höherer Konzentration führte zu mehr Absorption von ¹⁴C, förderte aber nicht die Translokation. Das Glyphosat wurde von den behandelten Blättern zu 25 bzw. 41% aus den großen Oder den kleinen Tröpfchen aufgenommen, aber die Translokation in die unterirdischen Pflanzenteile war etwa 7% der ausgebrachten ¹⁴C-Aktivität. Die in neuen Rhizomen akkumlierte Radioaktivität entsprach 0,5 μg g^?1 TM Glyphosat, mindestens 30mal weniger als für die Abtötung von Gewebe erforderlich.     

Dieldrin transport in the insect: an examination of Gerolt's hypothesis

[¹⁴C]-Dieldrin was detected in the hemolymph of adult male Periplaneta americana and P. brunnea 2.5 hr after an acetone solution of radiodieldrin (RD) was applied to the pronotum. Sephadex thin-layer gel filtration (TLG) of cell-free hemolymph (HL) from cockroaches to which RD was applied, and TLG of HL to which RD was added directly, indicated that dieldrin binds to a protein (s) of ca. 18,900 mol wt and two groups of proteins of mol wt ≥ 160,000. The capacity of Periplaneta HL for RD at 22°C was to at least 57 μM, but the highest concentration of RD detected in HL after topical application was 29.9 μM. The hemocytes contained about 37% of the dieldrin in whole cockroach hemolymph. When isolated cockroach legs were perfused with HL containing protein-bound RD, autoradiography of the dissected legs revealed ¹⁴C counts in the tissues. These findings are consistent with the translocation of topical dieldrin by hemolymph, but do not eliminate the possibility of translocation via the tracheal system.