摘要:

RésuméLa dégradation du propyzamide a étéétudiée après dépôt sur diverses bentonites homioniques. Les meilleures activités sont obtenues avec les bentonite Ag+et Cu++qui provoquent la dégradation du propyzamide selon un processus en deux étapes. La présence d'humidité provoque l'apparition d'un processus seconda

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00564.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryPre‐harvest application of glyphosate in barley at 1·44 and 0·72 kg ha−1was compared with post‐harvest application at 1·44 kg ha−1at six sites in south‐east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre‐harvest application gave consistent 95–99% control ofA. repenscompared with 0–76% control from post‐harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre‐harvest treatments and after one post‐harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre‐harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre‐harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre‐harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield l

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00565.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryExperiments were conducted in a growth cabinet to investigate the absorption and translocation of14C‐3, 6‐dichloropicolinic acid byCirsium 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 of14C‐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 inC. arvense.Absorption of 3,6‐dichloropicolinic acid was greater in vegetative than in floweringC. arvenseplants, 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 day

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00566.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryControl ofAvena fatua(L.) (wild oat) with diclofop methyl applied at 0·7 kg ha−1at the two‐leaf stage and difenzoquat at 0·84 kg ha−1at the four‐leaf stage in wheat (Triticum aestivumL.) under field conditions was good and not affected when either of these herbicides was mixed with 3,6‐dichloropicolinic acid as the monoethanolamine salt at 0·14, 0·20 or 0·30 kg ha−1. In the glasshouse, mixtures containing 3,6‐dichloropicolinic acid at rates as high as 0·6 kg ha−1also did not affect control ofA. fatua.When barban at 0·35 kg ha−1, or flamprop methyl at 0·56 kg ha−1was mixed with similar rates of 3,6‐dichloropicolinic acid and applied at the two‐leaf and four‐leaf stage ofA. fatuarespectively, a reduction in controlof A. fatua(antagonism) occurred under both field and glasshouse conditions. The herbicides for control ofA. fatuadid not influence the fresh weight suppression ofC. arvenseshoots obtained in the glasshouse with 3,6‐dichloropico‐colinic acid at 0·3 kg ha−1. Early tolerance of wheat (cv. Neepawa) was acceptable with all mixtures. Wheat yields with diclofop methyl or difenzoquat alone or in mixture with 3,6‐dichloropicolinic acid were increased over th

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00567.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryA survey of grass weeds of cereals in central southern England made in 1981 was repeated in 1982 between 28 June and 23 July. Dicotyledonous weeds were also assessed in 1982. A total of 1021 fields were surveyed, 702 in winter wheat. 198 in winter barley and 121 in spring barley. A total of twenty‐four grass weeds were found and their levels of infestation were scored. The most frequently found grass weeds were the same as in 1981. In all cereals combined, these wereElymus (Agropyron) repensin 35% of fields,Avena fatuain 32%,Alopecurus myosuroidesin 26% andPoa trivialisin 24%. Sixty‐three species of dicotyledonous weeds were recorded and of these, eighteen species occurred in 2% or more of fields. The eight most frequent wereViola arvensis, Galium aparine, Stellaria media, Myosotis arvensis, Polygonum aviculare, Convolvulus arvensis, Bilderdykia (Polygonum) convolvulusandLamium purpureum.Most species were fairly uniform in distribution, butGalium aparine, Convolvulus arvensisandCirsium arvensewere most frequent in the east whileViola arvensiswas least frequent there. The cereals varied in weediness, 32% of winter barley, 23% of spring barley and only 7% of winter wheat fields had no weeds recor

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00568.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryThe movement and degradation of simazine in the field during winter and summer were measured and compared with simulations using a simple model. The model only simulated simazine behaviour closely when water solubility was taken into account. Relationships between water solubility, melting point, soil adsorption and octan‐1‐ol/water partition coefficient indicate that, at agricultural rates of application, water solubility will only have an important influence on behaviour for relatively polar chemicals with high melting poi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00569.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryElymus repens(L.) Gould andAgrostis giganteaRoth. raised from rhizomes both responded to reduced light intensity by increased stem length, while the number of aerial shoots was reduced. The weight of the aerial parts was not influenced by a 50% reduction of the daylight intensity, but a further reduction of light caused a significant decrease in weight. The production of new rhizomes was more influenced by shading than were the aerial shoots. The consequence was an increase in the shoot/rhizome ratio.The food reserve per bud measured as inter‐node weight inE. repensandA. giganteawas reduced only with intensive shading, and the vitality of the rhizomes appeared independent of light intensity.Intensive shading in early as compared to late summer caused a reduction in the number and weight of aerial shoots, but not in the weight of new rhizomes. Light intensities equal to those found in a spring wheat crop allowed moreE. repensgrowth than light intensities equal to those in a spring oat crop.E. repensraised from seeds and grown at light intensities equal to those found in a cereal crop, showed insignificant rhizome productio

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00570.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryA simple, robust and inexpensive hand‐held meter is described which senses the presence of green vegetation against brown soil by measuring the ratio of near infra‐red (0·75 μm) to red (0·65 μm) radiances: ratios are higher for green canopies than for soil, due to strong absorption by chlorophyll of red wavelength and the high near‐infrared reflectance of healthy vegetation. Field tests showed that radiance data were correlated closely with plant density and growth stage. Such spectral assessments provide a rapid, nondestructive method of monitoring changes in green‐leaf biomass. Although only small differences in radiance values were recorded from monocultures of various non‐flowering species there was a positive correlation with content of white clover in five grass/clover swards. In addition to being a research aid, these findings confirm the potential of remote sensing of agricultural targets, e.g. detection of weed patches for herbicide spraying, or gaps in swards fo

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00571.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryIn glasshouse experiments, additions of 10–100 g 1−1ammonium sulphate enhanced the phytotoxicity to broadleaved weeds and cereals of several water‐soluble herbicides applied post‐emergence in 75–300 1 ha−1with hydraulic nozzles. Studies with dichlorprop potassium salt and chickweedStellaria media(L.) Vill. examined interactions between ammonium sulphate and environmental, application and formulation factors. Simulated rainfall immediately after spraying greatly reduced dichlorprop activity, whether or not ammonium sulphate was present. However, when there was an interval of 2–24 h between spraying and rainfall, the additive increased phytotoxicity. Surfactants tended to reduce dichlorprop phytotoxicity toStellaria media, both in the presence and absence of ammonium sulphate. Certain other inorganic salts including sodium sulphate also enhanced phytotoxicity. Applications by rotary atomizer in very low spray volume (15 1 ha−1, 250–280 μm drops) were less effective than conventional 150 1 ha−1applications. When very low volume application was used, addition of ammonium sulphate or nitrate tended to reduce activity further. In the field, ammonium sulphate significantly increased the effects against weeds of a commercial dichlorprop potassium salt formulation applied conventionally in 200 1 ha−1spray volume. Neutralized phosphoric acid had a similar effect but a mixture of this additive and ammonium sulphate reduced phytotoxicity. Both additives slightly increased dichlo

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00572.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY