摘要:

SummaryThe grass weed herbicide metolachlor (2‐chloro‐N‐[2‐ethyl‐6‐methylphenyl]‐N‐[2‐methoxy‐1‐methylethyl]acetamide) which is especially effective against wild millets, inhibits the formation of epicuticular waxes on sorghum leaves. The metolachlor protectant CGA 43089 [α ‐ (cyanomethoximino) ‐ benzacetonitrile] prevents the depletion of the waxes on the leaves of metolachlor‐treated sorghum plants, as demonstrated by scanning electron microscopy. This alteration of the plant surface polymers also changes their permeability to the herbicide.14C‐metolachlor uptake into isolated coleoptiles and first leaves of sorghum which had been pretreated with the herbicide was increased. Incubation with added protectant reduced the uptake of14C‐metolachlor. It is postulated that the modifications caused by metolachlor and its protectant to sorghum surface structures influence the action of the herbicide in two ways:1The selectivity observed against sorghum and millet grasses could occur because of an increased uptake of metolachlor through cuticles which are particularly sensitive to the structural changes caused by the herbicide, since the composition of the plant waxes is very species‐specific.2The loss of cuticular integrity is prevented by the protectant CGA 43089, which greatly

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00506.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SummaryThe influence of foliar sprays of EPTC, fluorodifen and monuron on transpiration and photosynthetic oxygen output ofEupatorium odoratumplants is demonstrated. Foliar sprays with 100 ppm EPTC or monuron led to a significant decrease in transpiration for a continuous period of 14 days. Treatment with 100 ppm fluorodifen led to a noticeable increase in transpiration during the first eight days. All three herbicides significantly reduced photosynthetic oxygen output from theEupaioriumplants. EPTC and monuron however, gave greatest effect. Reduction in transpiration from the plants was due to stomatal closure while reduction in photosynthetic oxygen output was due to both stomatal closure and probably also inhibition of the Hill reaction.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00507.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SummaryAn investigation of the persistence of trifluralin was conducted as field experiments over a two year period at latitudes 60°N and 70°N respectively, paying special attention to the soil and climatic conditions. These experiments included glasshouse bioassays withLolium multiflorum. gas‐chromatographic residue analyses and qualitative and quantitative studies on soil bacteria. Special attention was devoted to clay minerals as well as to the soil organic matter. 100 g or 500 g of trifluralin a.i. ha−1were applied in the spring 1978 with a reapplication on half of the area the following spring (1979).The phytotoxicity of trifluralin appeared more severe on re‐treated plots compared with single applications even at approximately equal residue levels. Trifluralin did not seem to have any real influence on the total number of soil bacteria. A qualitative change of the bacterial flora was however observed as a relative increase of non‐sporeformers, Gram negatives and Actinomy‐cetes and a relative depression of the Coryneform bacteria/Arthrobacter group.Even at a recommended dosage, a carry‐over phytotoxicity the following year may occur, especially when the content of organic matter in the soil is low. Care should therefore be taken when using this herbicide on the same field in two successive years. The properties of the soil seemed to exert a greater influence than the climatic factors on the persistence o

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00508.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SummaryThe contact action of difenzoquat was investigated on seedlings of spring wheat (Triticum aestivumL.) cultivars tolerant (Maris Butler) and susceptible (Sicco) to the translocated etTect of the herbicide on the apical meristem. Applied as a spray the chemical caused an increase in electrolyte leakage before the development of visible damage. Chlorophyll levels were also reduced and both effects were greater on Maris Butler than Sicco.Droplets of difenzoquat caused similar ultrastructural effects on the two cultivars. These included swelling of the chloroplasts with subsequent disorganization of the thylakoid system accompanied by disruption of other cellular components. Similar effects have been reported with paraquat and it is suggested that the contact action of difenzoquat is due to a weak paraquat type activity.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00509.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SummaryThe pattern of buthidazole {3‐[5‐(1,1‐dimethyl ethyl)‐1,3,4‐ thiadiazol ‐2‐y1]‐4‐hydroxy‐1‐methyl‐2‐imidazolidinone} metabolism and its potential contribution to crop selectivity were studied in tolerant corn (Zea maysL., ‘Pioneer 3780’) and susceptible redroot pigweed (Amaranthus retroflexusL). Thin‐Layer Chromatographic (TLC) analysis of methanol soluble extracts revealed that both corn and redroot pigweed seedlings metabolized buthidazole in a similar manner but at different rates. At comparable time periods redroot pigweed contained a greater percentage of unmetabolized14C‐buthidazole than did corn. A major unidentified metabolite with polar properties was formed faster in corn that in redroot pigweed and appeared to be important for the observed crop selectivity of buthidazole. Additional metabolites of buthidazole formed in both species had TLC properties similar to those of the amine, urea, and dih

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00510.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SummaryThistles in the genera Carduus, Cirsium, Onopordum, and Silybum of the subtribe Carduinae have been the subjects of considerable research designed for chemical, biological, cultural, and integrated control in the United States. Problems and costs associated with chemical and cultural control techniques stimulated the introduction of biological control agents from many locations in Europe and the Middle East. Although some natural enemies have successfully suppressed thistle infestations, economic losses during the time lags between introduction and effective suppression prompted investigations into integrated control procedures. The rationale, history, and potential direction for thistle suppression has been documented in this manuscript.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00511.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

RésuméL'influence de l'époque de levée des plantes porte‐graines et de la période climatique de dissémination sur la dormance des graines d'Amaranthus retroflexusL. prélevées uniquement au niveau de l'inflorescence principale a étéétudiée.Dans les conditions favorables de germination (30 C), les graines récoltées le plus tardivement (mois de novembre) sont, à leur dissémination, les moins donnantes et celles produites très tôt (mois d'août) les plus dormantes. Mais après conservation au sec pendant 60 jours, les graines ont une capacité germinative voisine de 100%, quelle que soit leur origine.Dans les conditions moins favorables de germination (20 C), les graines récoltées sur les plantes qui se sont développées très tard (juinjuillet) germent miex que celles prélevées sur les plantes apparues très tôt (mars‐avril). Ces différences ne sont pas supprimées par la conservation au sec.A la lumière de ces données, les auteurs discutent des interactions des effets entre les facteurs climatiques et l'état physiologique des plantes sur l'aptitude à germe

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1982.tb00512.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY