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Seeds of winter annuals require a summer after‐ripening period for dormancy loss and low autumn temperatures for germination. With current and future changes in moisture and temperature, we tested the effects of warming along a relative humidity (RH) gradient on dormancy loss and effects of decreased diurnal temperature range (DTR) on germination. We further reasoned that the effects of changes in these variables would be disproportionate between the exotic and native winter annuals. Seeds of exotic species (Buglossoides arvensis, Lamium purpureum and Ranunculus parviflorus) and co‐occurring native species (Galium aparine, Paysonia stonensis and Plantago virginica) were collected in middle Tennessee. After‐ripening occurred over a 15–100% RH gradient at 25 and 30°C and germination was tested at 20/10 and 20/15°C. Niche breadth was calculated using Levins' B. Fresh Ranunculus seeds had high germination and those of other species did not. Germination for these species increased with after‐ripening, mostly across the RH gradient irrespective of temperature. A decrease in DTR showed mixed results – the extreme being Ranunculus with no germination at 20/15°C. Most exotic species had wider germination niche breadths than native species. With climate change, we suggest that a decrease in DTR may have a larger effect on germination than increasing moisture or warming on dormancy break. Moreover, there is not a clear‐cut winner with climate change when we compare exotic versus native species because the responses of our six species were species specific.

In the rhizosphere, plants are exposed to a multitude of different biotic and abiotic factors, to which they respond by exuding a wide range of secondary root metabolites. So far, it has been unknown to which degree root exudate composition is species‐specific and is affected by land use, the local impact and local neighborhood under field conditions. In this study, root exudates of 10 common grassland species were analyzed, each five of forbs and grasses, in the German Biodiversity Exploratories using a combined phytometer and untargeted liquid chromatography‐mass spectrometry (LC‐MS) approach. Redundancy analysis and hierarchical clustering revealed a large set of semi‐polar metabolites common to all species in addition to species‐specific metabolites. Chemical richness and exudate composition revealed that forbs, such as Plantago lanceolata and Galium species, exuded more species‐specific metabolites than grasses. Grasses instead were primarily affected by environmental conditions. In both forbs and grasses, plant functional traits had only a minor impact on plant root exudation patterns. Overall, our results demonstrate the feasibility of obtaining and untargeted profiling of semi‐polar metabolites under field condition and allow a deeper view in the exudation of plants in a natural grassland community.

Three Galium species are believed to be present across western Canada: Galium aparine, Galium spurium and Galium boreale. Galium spurium and G. aparine are very difficult to distinguish morphologically, which is problematic for crop consultants and weed surveyors, and could have implications for control measures. Molecular techniques could potentially make identification easier and more rapid than using chromosome counts, as is currently done. The objective of this study was to identify morphological traits and/or genetic polymorphisms capable of species differentiation. To this end, Galium seed of unknown speciation were collected from nine field populations across western Canada and, along with two reference samples of G. spurium and G. aparine, were characterised for both morphological traits and their ribosomal ITS1‐5.8S‐ITS2 genomic sequence. In addition, single nucleotide polymorphism variation within the highly conserved 5.8S ribosomal RNA gene was identified that could consistently differentiate Galium species. Sequence analysis of the ITS1‐5.8S‐ITS2 region of field collections from western Canada indicated that all samples were G. spurium and all were highly related to each other. These results were supported by a distinct lack of variation in morphological traits, as nearly all plant traits measured did not differ between populations. This suggests that all sampled populations, and perhaps most of the Galium populations across western Canada, are derived from a single species, G. spurium.

Data on the chromosome counts of ten taxa of the genus Galium are reported from northeastern Iran. Two basic chromosome numbers, i.e. x = 10 and x = 11, as well as three ploidy levels, i.e. 2x, 4x and 6x are reported. Both diploid and polyploidy levels are observed. Aneuploidy was only observed in G. aparine. The chromosome numbers of the following taxa are counted for the first time: G. diploprion, G. humifusum, G. nigricans with 2n = 22 and G. spurium subsp. ibicinum with 2n = 20. The new data are compared with previous karyological information, and are discussed. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Epizoochory has been less studied than other seed dispersal mechanisms, such as endozoochory, and generally only a small percentage of plant species show adaptations to this strategy. Nevertheless, epizoochorous seed dispersal can affect an appreciable number of herb species in forests and man-made habitats. Also, few studies have dealt with temporal variation in epizoochory. In this paper, medium-long distance epizoochory is analyzed in a hedgerow habitat for the first time, using a domestic dog in an area in northwest Spain. Special attention is paid to seasonal variation and differential traits of plant taxa involved. Approximately 30 % of available herb taxa were found attached to hair. The intermonthly difference in the frequency of the taxa involved in epizoochory was significant, and the overall peak was reached in June–October linked with diaspore ripening phenology. Ninety-three percent of the plant taxa adhered to hair had diaspores with traits facilitating epizoochory (hooks, spines, awns, rigid hairs), in comparison with 17 % for available plant taxa not adhered to hair. The taxa involved in epizoochory had larger diaspores than the rest of the available taxa, but ranged considerably in size. Numerous hooks covered the largest, heaviest diaspores, and allowed them to attach to hair. There was no significant difference in mean plant height between taxa involved in epizoochory and the rest of the available taxa. The difference in life span between taxa involved in epizoochory and the rest of available taxa was not significant, most of them being perennials in both cases. Seventy-three percent of all the available plant taxa were potential forest plants typically found in edges and gaps, and 64 % of the plant taxa involved in epizoochory were these kinds of potential forest plants. High or medium involuntary positive selection by the dog of diaspores of Taraxacum gr. officinale, Galium aparine, Geum urbanum, and Agrimonia eupatoria was observed. In conclusion, epizoochorous dispersal can be quantitatively and functionally important in hedgerow habitats during summer-autumn, affecting mainly herb taxa with specialized diaspores.

Royo-Esnal A, Torra J, Conesa JA & Recasens J (2012). Emergence and early growth of Galium aparine and Galium spurium. Weed Research. 52, 458–466. Summary With the aim of improving the control of Galium aparine and G. spurium, field experiments were conducted in a Mediterranean winter cereal field. Emergence and early growth (in number of whorls) of six populations of these weeds were examined. Populations were sown in November 2005 and 2006 with four randomised complete blocks in north-eastern Spain. Emergence was determined by counting and marking newly emerged seedlings weekly for 3 months and vegetative growth was evaluated for each marked seedling group using the expanded BBCH (Biologische Bundesanstalt Bundessortenamt and Chemical industry) scale. Linear regressions were successfully fitted to the growth, using degree days and hydrothermal time as factors. Growth pattern differed between both years, but not between both Galium species, when fitted to growing day degrees (GDD), but these differences disappeared when fitted to hydrothermal time (HTT). Despite disparity in the emergence pattern among populations, new whorl production followed similar patterns for each Galium species, which allowed development of a common model. Maternal factors may have affected emergence, but populations did not show differences in whorl development. This growth model is a new tool that may be used to improve the timing of weed control strategies for Galium species in winter cereal fields under a Mediterranean climate.

 Premise of the study : Dioecy occurs in only about 6% of angiosperms, yet it has evolved many times from hermaphroditism. Polygamy is an even more uncommon condition within angiosperms, in which both unisexual and bisexual fl owers occur within a species. Polygamy, dioecy, and hermaphroditism all occur within a New World clade of Galium (Rubiaceae), in which dioecy is hypothesized to have evolved from hermaphroditism via polygamy. At least fi ve sections of Galium as traditionally defi ned by fruit morphology occur within this group. We tested the monophyly of sections defi ned by fruit morphology and sought to determine origins and pathways of breeding systems within this group.  Methods : We obtained chloroplast ( rpoB-trnC, trnC-psbM, trnL-ndhJ ) and nuclear ribosomal (external transcribed spacer) DNA sequences for 89 taxa from the Cruciata-Galium-Valantia (CGV) clade to estimate the phylogeny. Ancestral states for breeding systems, fruit types, and fruit hairs were reconstructed using parsimony and likelihood analyses.  Key results : We identifi ed nine well-supported lineages of New World Galium taxa. However, none of the sections traditionally defi ned by fruit morphology are monophyletic. Dioecy is inferred to have arisen at least three times from hermaphroditism; polygamy is inferred to have arisen at least twice from dioecy and at least six times from hermaphroditism.  Conclusions : Polygamy appears to be a terminal condition in the CGV clade and not a pathway to dioecy. Fruit characters traditionally used in the taxonomy of this group have arisen multiple times within this clade of Galium and are not reliable indicators of shared evolutionary history.

The emergence of three artificial cohorts of Galium aparine, G. spurium and G. tricornutum with different accessions was studied over two years under the climatic conditions of north-eastern Spain. Seeds were sown in November (first cohort), January (second cohort) and February (third cohort). Higher and lower emergence percentages were obtained in the first and third cohorts, when fresher winter and dry spring occurred. However, this tendency changed when the spring was wet and emergence of third cohorts was more than that of the first. Results suggest that low temperatures in winter break the dormancy of these species, that soil moisture promotes the germination and emergence of these weeds and that emergence is highly influenced by dormancy levels during winter and spring. Lack of rain does not allow spring germination, hence, application of herbicides to control spring cohorts is not necessary.

Buffer strips are refuges for a variety of plants providing resources, such as pollen, nectar and seeds, for higher trophic levels, including invertebrates, mammals and birds. Margins can also harbour plant species that are potentially injurious to the adjacent arable crop (undesirable species). Sowing perennial species in non-cropped buffer strips can reduce weed incidence, but limits the abundance of annuals with the potential to support wider biodiversity (desirable species). We investigated the responses of unsown plant species present in buffer strips established with three different seed mixes managed annually with three contrasting management regimes (cutting, sward scarification and selective graminicide). Sward scarification had the strongest influence on the unsown desirable (e.g. Sonchus spp.) and unsown pernicious (e.g. Elytrigia repens) species, and was generally associated with higher cover values of these species. However, abundances of several desirable weed species, in particular Poa annua, were not promoted by scarification. The treatments of cutting and graminicide tended to have negative impacts on the unsown species, except for Cirsium vulgare, which increased with graminicide application. Differences in unsown species cover between seed mixes were minimal, although the grass-only mix was more susceptible to establishment by C. vulgare and Galium aparine than the two grass and forb mixes. Annual scarification can enable desirable annuals and sown perennials to co-exist, however, this practice can also promote pernicious species, and so is unlikely to be widely adopted as a management tool in its current form.

Summary A pollen morphological investigation of eleven species and one subspecies of the genus Galium L. from Egypt were undertaken by using light microscope (LM) and scanning electron microscope (SEM). Pollen shape, size, exine ornamentation, number of apertures present powerful characters for distinguishing between species. The pollen grains were zonocolpate. The number of colpi ranges from 5 to 10. Their shape varies from prolate spheroidal, oblate spheroidal, spheroidal to suboblate. Three groups can be distinguished based on the size pollen grains. It was found used to distinguish between closely related species G. aparine and G. spurium and between G. tricornutum and G. ceratopodum. Two different types of exine ornamentation were recognized. The ornamentation was found useful to distinguish among closely related species such as Galium aparine and G. spurium. A key for the identification of the investigated taxa based on pollen grains characters is provided. Zusammenfassung

Living plant neighbours, but also their dead aboveground remains (i.e. litter), may individually exert negative or positive effects on plant recruitment. Although living plants and litter co-occur in most ecosystems, few studies have addressed their combined effects, and conclusions are ambivalent. Therefore, we examined the response in terms of seedling emergence and growth of herbaceous grassland and forest species to different litter types and amounts and the presence of competitors. We conducted a pot experiment testing the effects of litter type (grass, oak), litter amount (low, medium, high) and interspecific competition (presence or absence of four Festuca arundinacea individuals) on seedling emergence and biomass of four congeneric pairs of hemicryptophytes from two habitat types (woodland, grassland). Interactions between litter and competition were weak. Litter presence increased competitor biomass. It also had positive effects on seedling emergence at low litter amounts and negative effects at high litter amounts, while competition had no effect on seedling emergence. Seedling biomass was negatively affected by the presence of competitors, and this effect was stronger in combination with high amounts of litter. Litter affected seedling emergence while competition determined the biomass of the emerged individuals, both affecting early stages of seedling recruitment. High litter accumulation also reduced seedling biomass, but this effect seemed to be additive to competitor effects. This suggests that live and dead plant mass can affect species recruitment in natural systems, but the mechanisms by which they operate and their timing differ. Fil: Loydi, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Justus-Liebig University Giessen. Research Centre for BioSystems, Land Use and Nutrition. Institute of Landscape Ecology and Resource Management; Alemania Fil: Donath, T. W.. Justus-Liebig University Giessen. Research Centre for BioSystems, Land Use and Nutrition. Institute of Landscape Ecology and Resource Management; Alemania. Christian-Albrechts University. Institute for Natural Resource Conservation. Department of Landscape Ecology; Alemania Fil: Otte, A.. Justus-Liebig University Giessen. Research Centre for BioSystems, Land Use and Nutrition. Institute of Landscape Ecology and Resource Management; Alemania Fil: Eckstein, R. L.. Justus-Liebig University Giessen. Research Centre for BioSystems, Land Use and Nutrition. Institute of Landscape Ecology and Resource Management; Alemania

Summary The effects of nitrogen fertiliser on herbicide dose–response of weeds were investigated by measuring weed biomass after growth at a range of nitrogen levels and treatment with a range of herbicide doses. Increasing weed biomass at no-herbicide treatment (W0) and the response rate of the dose–response curve (B), with increasing nitrogen were successfully described by the linear model and the exponential model respectively. Conversely, decreasing ED50 value with increasing nitrogen was well described by the logistic model. A combined model was then developed by incorporating these models into the standard dose–response model to describe the interactive effects of herbicide dose and nitrogen levels on biomass of Brassica napus, Matricaria perforata, Papaver rhoeas and Galium aparine. The model developed allowed the systematic description of increased herbicide performance with increasing nitrogen. The model was also used to predict weed biomass as affected by both herbicide doses and nitrogen levels. The mathematical relationships between herbicide dose–response and nitrogen levels may also be applied to the crop–weed competition model and then to decision making for optimum uses of nitrogen fertiliser and herbicide.

Summary A series of eleven field experiments over two seasons investigated the control of Galium aparine (cleavers) with mecoprop and a proprietary mixture of ioxynil plus bromoxynil. Applications of mecoprop (2⋅4 kg a.e. ha−1) between December and March gave variable results but a mixture of ioxynil + bromoxynil (0⋅6 kg a.i. ha−1) and mecoprop improved control up to at least 90%, at most sites. Applications of mecoprop alone in April were most effective and frequently achieved more than 90% control. In May, when the G. aparine plants were very large, it was less successful. The reasons for the environmental effects on performance are discussed. Preliminary examination of the effect of soil temperature on mecoprop activity indicates that the reliability of control increases with increasing temperature (0–12°C). An average of 94% control was achieved when soil temperatures were greater than 6°C. La destruction de Galium aparine (Gaillet) dans les cereales d'hiver avec du mecoprop seul ou avec ioxynil plus bromoxynil Resume Une serie de 11 essais de plein champ sur deux ans a permis d'etudier la destruction de Galium aparine (gaillet) avec du mecoprop et une association de ioxynil plus bromoxynil. Des applications de mecoprop (2,4 kg ha−1)entre decembre et mars ont donne des resultats variables, en revanche un melange de (ioxynil + bromoxynil) (0,6 kg m.a. ha−1) et de mecoprop a ameliore la destruction jusqu'a au moins 90%, dans la plupart des sites. Des applications demecoprop (2,4 kg ha−1) entre decembre et mars ont donne des resultats variables, en revanche un melange de (ioxynil + bromoxynil) (0,6 kg m.a. ha−1) et de mecoprop a ameliore la destruction jusqu'a au moins 90% dans la plupart des sites. Des applications de mecoprop seul en avril se sont averees plus efficaces et aboutissaient souvent a une destruction superieure a 90%. En mai, quand les plantes de G. aparine sont bien developpees, c'est moins efficace. Les effets lies a I'environnement sur les performances sont discutes. Tout d'abord, l'etude de l'effet de la temperature du sol sur I'activite du mecoprop montre que l'efficacite herbicide croit avec la temperature (0–12°C). Un pourcentage moyen de 94% de destruction est obtenu quand la temperature du sol est superieure a 6°C. Die Bekampfung von Galium aparine (Kletten-Labkraut) in Wintergetreide mil Mecoprop allein oder mit Ioxynil plus Bromoxynil Zusammenfassung Die Bekampfung von Galium aparine mit Mecoprop und einer formulierten Mischung von loxynil plus Bromoxynil wurde in 11 Feldversuchen uber 2 Vegetationsperioden untersucht. Behand-lungen mit Mecoprop (2,4 kg AS ha−1) zwischen Dezember und Marz fuhrten zu unterschiedlich guten Ergebnissen, aber die Mischung von Ioxynil plus Bromoxynil (0,6 kg AS ha−1) mit Mecoprop verbesserte meistens die Wirkung auf mindestens 90%. Behandlungen im April mit Mecoprop allein waren sehr wirkungsvoll und erreichten oft mehr als 90% Bekampfung. Im Mai, wenn die Galium-aparine-Pflanzen weit entwickelt waren, wirkte es sehwacher. Die Grunde fur die Wirkung von Umwelteinflussen auf die Wirksamkeit wurden diskutiert. Vorlaufige Untersuchungen der Wirkung der Bodentemperatur auf die Wirksamkeit des Mecoprops ergaben, dass die Zuverlassigkeit der Bekampfung mit steigender Temperatur (0–12°C) zunimmt. Bei Bodentemperaturen uber 6°C wurden durehschnittlich 94% Bekampfung erreicht.

Florasulam is a triazolopyrimidine sulfonanilide post-emergence broadleaf herbicide for use in wheat (Triticum aestivum L.). The selectivity of florasulam to wheat has been determined to be related primarily to a differential rate of metabolism between wheat with a half-life of 2.4 h and broadleaf weeds with half-lives ranging from 19 to >48 h. To a lesser extent, selectivity, at least for the broadleaf weed cleavers (Galium aparine L.), involves uptake differences. Rate of metabolism data were generated using greenhouse-grown plants injected with radiolabelled florasulam and subsequent extraction and processing by high-performance liquid chromatography (HPLC). Structures of metabolites were determined by isolation for nuclear magnetic resonance and liquid chromatography/mass spectrometry. Wheat plants metabolised florasulam by hydroxylation of the aniline ring para to the nitrogen, followed by conjugation to glucose. Metabolism by broadleaf weeds was so slow that isolation of metabolite was not possible, but comparison of HPLC data suggested hydroxylation as the major pathway.

Two surveys were conducted to investigate weed vegetation in a 153-hm 2 sampling area of summer crop fields from Anhui Province, China, through visual scoring of the level of weed infestation compared with summer crops on a seven-class scale. In total, 155 sampling sites were selected in the field based on crops, tillage, rotation systems, geographical regions, and soil types across the province. Data on weed communities and environmental factors were collected and analyzed through principal component analysis (PCA) and canonical correspondence analysis (CCA), and the output was interpreted ecologically. Results showed that the main factors influencing the structure and distribution of weed communities in summer crop fields were the soil submersion period, latitude, and soil type and pH. The CCA indicated a significant relationship between weed dominance and soil submersion duration, latitude, and soil pH. From the result of the PCA and CCA ordination, the 155 sampling sites could be divided into three groups based on geographic and floristic composition, as well as weed abundance. The southern dry land group, which was characterized by a double-cropping system in the hilly regions of southern and central Anhui Province with a continuous summer crop and an autumn dry land crop, was dominated by Galium aparine Linn. var. tenerum (Gren. et Godr) Robb., Avena fatua L., and Veronica persica Poir. The northern dry land group, which had the same cropping system as the southern dry land group, was dominated by G. aparine var. tenerum, Galium tricorne Stokes, Descurainia sophia (L.) Schur., and Lithospermum arvense L. in the North Anhui Province, China. These two dry land groups could be combined into one large dry land group, in which the Galium weed vegetation type dominated. The third group was the paddy soil group, which was characterized by a continu- ous summer crop and double- or triple-cropping systems of rice, and prevailed in the south and central areas of Anhui Province; Alopecurus aequalis Sobol. was the dominant weed in this group. Other main weeds in this group included Malachium aquaticum (L.) Fries, Stellaria alsine Grimm, Alopecurus japonicus Steud., and Lapsana apogonoides Maxim. Thus, the weed community distributions in this group were described as the Alopecurus weed vegetation type. The paddy soil group could be divided into two subgroups, one southern and one central paddy soil subgroup. A strategy for integrated weed management is suggested according to the weed distribution pattern. The present study serves as a good example of how a quantitative research method was used to associate a visual estimate of weed infestation with multivariate analyses, such as PCA and CCA, and how this method can be applied to the study of weed vegetation on arable land.

Summary 1 We investigated spatial genetic patterns in the clonal herbaceous plant species Galium odoratum L., which has previously been shown to be significantly associated with ancient woodlands. 2 A maternally inherited chloroplast DNA marker was developed for G. odoratum . Seven chloroplast haplotypes were detected in the study area and mapped at different spatial scales. Their spatial patterns suggest that both local and non-local gene flow occurs via seeds. 3 Fingerprints from DIG-labelled AFLP technology were validated as markers for G. odoratum clone identification. A single primer‐enzyme combination was sufficient to distinguish between clones. A typical patch of G. odoratum is composed of numerous genets, mainly occurring in separate clusters of ramets, which may be several meters in diameter. 4 Pairwise similarities, calculated from the AFLP banding patterns, were used for spatial autocorrelation analysis. The distinct spatial genetic structure at the patch level may be due to the genetic similarity of neighbouring genets or to clonal growth. 5 The spatial patterns obtained using the two DNA markers, suggest that a mixture of local and non-local gene flow via both seeds and pollen is occurring. Repeated seedling recruitment (RSR) would be consistent with the life history of G. odoratum in ancient woodlands with long-term spatial continuity.

The effects of warming on a montane meadow was simulated by a translocation experiment. A coherent piece of turf and soil was transferred from 600 m to 170 m a.s.l., corresponding to an increase in temperature of ca . 2.8 K. The vegetation was monitored by recording cover and counting individuals one year before the translocation and continued for the subsequent seven years. For comparison, a control plot that had also been translocated but remained at 600 m was moni- tored. Four of eight species with a montane distribution in Europe showed a constant degree of cover during the investi- gation period (Nardus stricta, Poa chaixii, Polygonatum verticillatum, Potentilla erecta). In contrast, another four mon- tane species declined in cover or died out ( Arnica montana, Meum athamanticum, Hypericum maculatum, Galium harcynicum). None of these species declined on the control plot. It is argued that the species' responded individualistically to the site factors that had changed with the translocation to low altitude. A direct effect of enhanced temperature was probably the reason for the decline of only one species ( Meum athamanticum). Reduced humidity might be the reason for the extinction of two moisture demanding species (Viola palustris, Succisa pratensis). The biomass of the plot increased by increased growth of one of the matrix species ( Festuca rubra), probably due to elevated nutrient mineralization. Many low growing species responded indirectly to the reduced light availability, caused by an increased level of competition for light (e.g. Galium harcynicum). Increased slug herbivory at low altitude resulted in the extinction of Arnica montana. At the end of the investigation period, the similarity in species composition to the initial state was only 45%, indicating that the community had changed into a different plant association. The importance of considering biotic interactions when pre- dicting the impacts of climate change is discussed.

Photocontrol of weed germination of arable annual weeds Field studies were conducted to test the effect of light during soil tillage on the emergence of common weed species. Soil tillage was conducted at night or during daylight. In 20 out of a total of 23 field experiments, weed density after nighttime tillage was reduced compared to conventional daytime tillage. The average reduction of weed density attributable to photocontrol was 28.4 %. Results of field trials in the literature suggest that the emergence of Chenopodium album, Matricaria species and Stellaria media is especially reduced by nighttime tillage practices, but photocontrol had almost no effect on the emergence of Galium aparine and Polygonum convolvulus. The level of reduction of weed emergence after nighttime tillage was very variable. Important factors affecting this variation were: (1) the different light sensitivities of weed species, (2) the different light sensitivities of populations within one species, (3) the dormancy status of the seeds in a natural seed bank, and (4) the variation of light sensitivity of seeds. Zusammenfassung In dieser Untersuchung wurde die Wirkung der photobiologischen Unkrautkontrolle auf die Unkrautdichte im Feldversuch unter Praxisbedingungen quantifiziert. In 20 von 23 Feldversuchen war die Unkrautanzahl nach Nachtbodenbearbeitung geringer als nach konventioneller Tagbodenbearbeitung. Im Durchschnitt aller 23 Versuche liefen 28,4 % weniger Unkrauter nach Nachtbodenbearbeitung auf. Resultate anderer Arbeitsgruppen und die eigenen Ergebnisse lassen den Schlus zu, das vor allem die Keimung der Unkrautarten Chenopodium album, Matricaria species und Stellaria media sehr haufig durch Licht gefordert wird und diese Arten mit hoher Wahrscheinlichkeit durch Nachtbodenbearbeitung zuruckgedrangt werden konnen. Dagegen wurde die Keimung von Galium aparine und Polygonum convolvulus nur selten durch Nachtbodenbearbeitung verhindert. Das Ausmas der Unkrautreduzierung durch photobiologische Unkrautkontrolle ist sehr starken Schwankungen unterworfen.

Forty-eight wood mice Apodemus sylvaticus were radio-tracked over an estimated 1500 h yielding 9000 fixes. The mice were living in three contiguous arable fields, and showed that they respond to weedy microhabitat patches within superficially homogeneous crops. Plant species' abundance and the composition of the seed bank were assessed in quadrats taken in areas in which (a) mice foraged, (b) through which mice travelled, or (c) at random within each home range. Wood mice avoided foraging in areas with a high abundance of bare earth, and selected areas with a high abundance of Alopecurus myosuroides, Stellaria media, Avena fatua, Galium aparine or Bromus sterilis. The food plants apparently selected by wood mice differed markedly between months and between sexes. This may relate to the energetic and nutritional demands incurred by the contrasting reproductive tactics of male and female wood mice. There were no differences between seed bank samples taken from quadrats where the mice foraged, travelled through, or which were selected at random. Our study, the first large-scale analysis of wood mouse microhabitat preference using radio-tracking, reveals that whereas the mice do not react to heterogeneity on the scale of the mosaic of crop fields, they are greatly influenced by the dispersion of food plants within the superficially homogeneous crop itself.

Elofsson, M. & Gustafsson, L. 2000. Uncommon vascular plant species in an EastCentral Swedish forest area - a comparison between young and old stands. - Nord. J. Bot. 20: 51-60. Copenhagen. ISSN 0107-055X. Abundance of uncommon vascular plant species (indicator species and red-listed species) was recorded in 120 circular (12.6 m2) random plots in young (10-24 years after clearcutting) and old (>80 years) forest stands, respectively, in the forest area of Vallen (2 600 ha), ca. 80 km north of Stockholm, Sweden. Factors describing stand density, field-layer and soil moisture were recorded. A total of 16 species were observed and of these 14 were found in old and 9 in young stands. Seven species occurred exclusively in the old stands and two in the young stands. The total number of species records was significantly higher in young than in old stands, 80 and 71, respectively. Mean number of records per ha was ca. 530 for the young stands and ca. 470 for the old. Of the five species common enough to be tested, a difference was only found for Paris quadrifolia, which was significantly more frequent in young than old stands. Galium odoratum, Hepatica nobilis, Lathyrus vernus and Paris quadrifolia grew in significantly more sheltered sites, e.g. beneath other herbs and grasses or close to shrubs and trees in young compared to old stands. Nested subset analysis showed that the whole data-set had a nested structure. Galium odoratum was significantly nested and thus indicated rich plant assemblages. In this calcareous area with nutrient-rich forest soils, there evidently is a potential for at least some uncommon vascular plant species to survive the phases following clearcutting. The study indicates that green-tree retention at final fellings and avoidance of heavy shrub removal during cleaning are beneficial to the flora.

Galium catalinense subspecies acrispum (Rubiaceae) is a state-endangered perennial shrub endemic to San Clemente Island. Eight polymorphic microsatellite loci were isolated from G. catalinense ssp. acrispum. These loci show high levels of variability, averaging 6.5 alleles per locus and an expected heterozygosity of 0.550. One locus exhibited significant deviations from Hardy-Weinberg equilibrium (P < 0.01) and one pair of loci exhibited significant linkage disequilibrium.

Weed suppression characteristics of different winter cereal species and cultivars were studied in two field experiments in two successive years. Two cultivars each of barley, oats and wheat were studied using the weed Galium aparine L. at a range of densities. Significant differences were found in the suppressive abilities of the crop species: oats being the most suppressive, followed by barley and then wheat. Percentage yield loss was related to G. aparine density using a rectangular hyperbolic model. In 1995-96, significant differences between the two wheat cultivars were found, with cv. Avalon being able to suppress G. aparine growth much more effectively than cv. Spark. However, in 1996-97, high rainfall in May, June and July enabled G. aparine to escape suppression by the cultivars. Cultivar competitive ability was associated with high overall leaf area, resistance to loss of tillers under competitive pressure, greater height, canopy structure and development. The oat cultivars were more competitive at early growth stages than could be accounted for by their canopy structure; the possible contribution of allelopathic exudates to their suppressive ability is discussed.

Galium aparine plants were treated at the two-whorl stage with technical-grade phenmedipham. The active ingredient was applied at 10 doses as an acetone:water solution, without emulsifier, alone or in mixture with an ester of oleic acid (methyl, butyl, octyl, dodecanyl, octadecanyl). The plant response was described by a log-logistic regression model. Phenmedipham applied alone did not kill the plants even at the highest dose (1621 g a.i. ha -1 ). In contrast, addition of any alkyl oleate to phenmedipham killed the plants at the 200-400 g a.i. ha -1 doses. The alkyl oleates differently affected activity of phenmedipham. Their effects could be ranked as follows: butyl ≥ methyl; octyl > methyl; dodecanyl ≤ methyl; octadecanyl < methyl oleate. Thus, butyl and octyl oleate promoted phenmedipham activity more than methyl oleate.

Investigations were conducted to elucidate the mechanism of selectivity of the auxin herbicide, quinmerac, in cleavers (Galium aparine) and the tolerant crops sugarbeet (Beta vulgaris), oilseed rape (Brassica napus) and wheat (Triticum aestivum). After root treatment with the herbicide, the selectivity has been quantified as approximately 400-fold between oilseed rape and Galium and 1000-fold between sugarbeet or wheat and the weed species. When 1 and 10 μM [ 14 C]quinmerac were applied for 4 h, no significant differences between root absorption and translocation of 14 C by Galium and the crop species were found. After 16 h, metabolism of [ 14 C]quinmerac to the biologically inactive hydroxymethyl and dicarboxylic acid derivatives was more rapid in wheat and sugarbeet than in Galium. In oilseed rape, a lower rate of herbicide metabolism was observed. In Galium, accumulations of abscisic acid (ABA), triggered by quinmerac-stimulated ethylene biosynthesis, were found to cause the herbicidal growth inhibition which develops during 24 h of application. Within 1 h of treatment, quinmerac stimulated 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity and ACC concentration specifically in Galium shoot tissue. During the next 4 h, ACC synthase activity was increased up to 50-fold, relative to the control. Within 3 h of exposure to quinmerac, increased ethylene formation followed by higher ABA levels was detected. In sugarbeet, oilseed rape and wheat, quinmerac did not stimulate ACC synthase activity and ACC and ABA levels. It is suggested that (i) the selectivity of quinmerac is primarily based upon the lower sensitivity to the herbicide of the tissue/target in the crop species, (ii) the induction process of the ACC synthase activity in the shoot tissue is the primary target of herbicidal interference. In wheat and sugarbeet, tolerance to quinmerac is additionally increased by a more rapid metabolism.

Field experiments were conducted in two winter wheat fields to assess weed control and quantify the amount of herbicide applied with a GIS map-based patch sprayer. Site specific weed management decisions were based on previously acquired weed distribution maps and an economic weed threshold model. A weed treatment map (on-off) was generated and georeferenced to control the sprayer. A global positioning system was used to locate the sprayer in the field. In both fields, Alopecurus myosuroides was observed at low infestation levels. Galium aparine at medium infestation levels and the mean density for other broadleaf species exceeded 40 weed seedlings m -2 in both fields. Herbicide application was recommended for 58.3 % of the first field and 54.6 % of the second field. With the patch sprayer used for this study, 21% less herbicides were sprayed compared to an uniform broadcast application. Additional assessments of weed density in the first field 3 and 6 weeks after site specific weed control showed that almost the entire field was weed free. The results of this study demonstrated that site specific weed control was technically feasible but further investigations are needed to verify and evaluate site specific weed control methods.

Weed communities, comprising 12 introduced species at constant starting densities and three species already present in the seed bank, were followed through three years of continuous winter wheat. The wheat and weeds were subjected to two treatments in a split-plot factorial design, organic contrasting with conventional fertilizer, and ploughing plus hand-roguing contrasting with minimum tillage plus herbicide. The minimum tilled plots developed in a uniform manner, and became dominated by very high densities of Anisantha sterilis. Agrostemma githago and Galium aparine also persisted in these plots at lower densities. The ploughed plots had a lower total density but a greater range of species. Stellaria media, Veronica persica and Avena fatua were the most common; other species occurred at lower densities. The major effect of fertilizer treatment was a greater initial increase by G. aparine on the organic, minimum tilled plots compared with the conventionally fertilized, minimum tilled plots. Species associated with minimum tillage were annuals with either no or a short term seed bank and autumn germination and rather predictable dynamics, whereas species that did well under ploughing were either spring germinating or had a persistent seed bank, implying greater annual variation in population size associated with weather conditions. There seemed no clear way to distinguish between those species which were abundant on the ploughed plots and those which were scarce under all conditions using readily accessible data.

Biomass, plant size, plant density and the inequality of sizes were assessed for autumn-emerging roadside populations dominated by Galium aparine during early stages of growth in two independent studies. A third data set dealt with the survival of labelled seedlings belonging to different cohorts of emergence. One data set showed that the slope of the log-log size/density relationship for all plant species present in the samples was closer to −1.5 and that for G. aparine was closer to −1.0 in five separate populations. Biomass increase and density decrease was not found to take place in any of these simultaneously. The size inequality of G. aparine tended to increase or to remain constant during periods of high mortality, and in the early harvests it was negatively related to population density. The second data set revealed simultaneous decreases of both biomass and density of G. aparine and of all plant species during a period of a month soon after emergence, and a higher size inequality of G. aparine in those patches where plant density (and that of G. aparine) was lower. The labelling of seedlings indicated density-dependent mortality and a higher probability of survival for seedlings emerging very early. The size/density relationship of roadside populations dominated by G. aparine may follow a trajectory over time similar to that predicted by the 3/2 power law of self-thinning, but this species seems to have a weak size hierarchy development and limited individual growth at high population densities. The importance of plant architecture in relation to this response is discussed.

Summary Seedling emergence of Alopecurus myosuroides Huds., Stellaria media L. (Vill.), Galium aparine L. and wheat (Triticum aestivum L.) was compared at a range of depths of soil cover from 2 to 11 cm. The covering soil was a fertile agricultural soil with 60% clay content which had been sieved into four aggregate sizes. The aggregate sizes used were 26-50 mm. 14-25 mm. 6-13 mm and below 6 mm. Total emergence of all species was reduced with increased depth of sou cover. With A. myosuroides and S. media, total emergence was lowest in fine soil conditions. Alopecurus myosuroides showed a marked interaction whereby response to depth of sowing was least with fine tilth. The time to 50% emergence showed a similar response. With all four species, seedling emergence was slowest at greater depths of sowing and with the finest tilth, the differences tending to increase with increasing depth of sowing. A vert high proportion of the time to 50% emergence was accounted for by the lag time between sowing and the first recorded emergence.

Summary In an investigation of the possible reasons for tolerance lo fluroxypyr by Galium aparine L. (cleavers), a wide range of variation in total herbicide retention was exhibited by nine diverse populations from throughout Europe. Although these differences in fluroxypyr relention became negligible when considered on a unit area basis, a two-fold difference was maintained per unit dry matter. There was no difference in fluroxypyr uptake between a fluroxypyr-tolerant and a fluroxypyr-susceptible population, and differences in translocation between the two populations did not seem to explain the differential tolerance. It is suggested that differential metabolic detoxification may be the main reason for the variation in response to fluroxypyr by populations of G. aparine.

Goat grazing is examined as a possible tool for grassland management. In this paper, goat grazing preferences are described. The proportion of biomass of particular species eaten by a goat was estimated on the basis of comparison of paired quadrats. The control quadrats were clipped before grazing and their biomass was compared with the biomass in grazed quadrats. Estimates of the proportion consumed were calculated for frequent species; they were significantly differ- ent among species; the most preferred species was Polygonum bistorta, a species with broad, soft, nutritious leaves. The least grazed species were Agrostis tenuis and Galium harcynicum. Various indices of food selectivity (e.g. forage ratio, electivity index) were calculated and their behaviour was compared. Canonical Correspondence Analysis and Redundancy Analy- sis with appropriate covariates reflecting the block design of the experiment were used to evaluate overall changes in spe- cies composition and yielded results similar to those from the direct estimation of the proportion consumed.

In a screening of South African indigenous food plants for antioxidant activity by testing for inhibition of lipid peroxidation, the “potherbs”Amaranthus sp., Sisymbrium thellungii, and Urtica dioica had very high activity. This activity was greatest in the boiled extract of Amaranthus sp. and the boilet and aqueous extracts of Sisymbrium thellungii and Urtica dioica. The activity in the aqueous extract of Nasturtium aquatica was lost by boiling. High activity was also obtained with the teas Galium aparine and Aspalathus linearis (Rooibos) and with the tuber Colocasia esculenta.

We report preliminary results of a series of experiments designed to explore the importance of interspecific competition within arable weed communities at different scales. Competition hierarchies were apparent from a pot experiment with different levels of nutrients and water. Two field experiments looked at Bromus sterilis, Galium aparine and Papaver rhoeas in winter wheat in the field, in a range of combinations and management treatments, and a fourth field experiment included a wider variety of species. There was little effect of fertilizer on population behaviour in the the field. Bromus increased around ten fold per year on minimum-tilled plots, regardless of other treatments. Galium increased on organically-fertilized and minimum-tilled plots, but only in the absence of Bromus. Papaver densities remained low, but again were depressed in the presence of high densities of Bromus. Taken together, the experiments demonstrate the existence of competition between weed species. However, as the design of the experiment increased to include greater levels of environmental variation, so competition became more difficult to detect, and less useful for interpreting the results than knowledge of the biology of the individual species. At the scale of interest to the farmer, the level of competition is not a good predictor for weed population dynamics.

Automatic identification of 10 weed species in digital images using Fourier descriptors and shape parameters Plant species discrimination in mixed plant communities has recently become possible using transforms and shape parameters to classify digital images. In the present study image analysis techniques were used to identify weeds commonly found in winter cereal fields. Those species included Veronica hedenfolia L., Thlaspi arvense Beauv., Alopecurus myosuroides L., Apera spica-venti L., Poa annua L., Stellaria media L., Capsella bursa-pastoris L., Lamium purpureum L., Matricaria chamomilla L. and Galium aparine L. Images of several growth stages of these weeds were photographed using a Still Videokamera, binarified, the shape extracted and then Fourier descriptors and shape parameter were calculated for each weed. Classified digital images of each species were stored on the computer. A separate set of photographic images of these 10 weeds were used to test the ability of the classified images for plant identification. The average rate of correct identification was 81.9 % ranging from 41.6 % to 100 %. Zusammenfassung In dieser Arbeit wurde ein Verfahren zur Erkennung von zehn Unkrautarten im Wintergetreidebau entwickelt. Diese zehn Spezies sind: Veronica hederifolia L., Thlaspi arvense Beauv., Alopecurus myosuroides Huds., Apera spica-venti L., Poa annua L., Stellaria media L., Capsella bursa-pastoris L., Lamium purpureum L., Matricaria chamomilla L. und Galium aparine L. Die Unkrauter wurden mit einer elektronischen CCD-Still-Videokamera im Herbst 1991 aufgenommen. Anschliesend wurde die ausere Kontur der Unkrauter im Binarbild extrahiert und Fourierdeskriptoren sowie Formparameter berechnet und im Speicher des Rechners abgelegt. Eine Wissensbasis aus einigen reprasentativen Individuen jeder Art wurde aufgebaut. Die Wiedererkennungsstudie erfolgte mit anderen Individuen der gleichen Spezies. Folgende Ergebnisse lassen sich zusammenfassen. 1. Die durchschnittliche Wiedererkennungsrate der untersuchten Unkrautspezies betrug 81,9 % und variierte von 41,6 % fur Galium aparine bis 100 % fur Veronica hederifolia. 2. Die Zeit der Wiedererkennung fur ein Unkraut betrug mit einem 10-MHz-Rechner ohne Coprozessor je nach Komplexitat der auseren Kontur und der Grose der Wissensbasis 30 bis 39 Sekunden.

Summary: Resume: Zusammenfassung Cultivating with a flexible tine harrow in the autumn reduced densities of Stellaria media (L) Vill., Galium aparine L. and Brassica napus L. plants and thinned the wheat crop. Effects were more severe with two passes at right angles (plant stands were approximately halved) than with a single cultivation. Despite crop thinning, wheat yields were not reduced by autumn harrowing owing to compensatory increases in 1000-grain weights. Summer biomass of S. media and G. aparine was reduced more by spring than by autumn harrowing, while biomass of B. napus was only reduced by autumn harrowing. It was concluded that weakly rooted climbing or scrambling species are more easily controlled by cultivating in the spring, while species that develop a tap-root are more readily controlled by cultivating at an early growth stage in the autumn. L'effet de differentes frequences d'hersage en automne on au printempssur le ble d'hiver, etsur les controles suivants Stellaria media (L.) Vill., Galium aparine L. et Brassica napus L. Les facons culturales effectuees a 1'automne avec une herse a trilles flexibles reduisaient le nombre de Stellaria media (L.) Vill., Galium aparine L. et Brassica napus L. et eclaircissaient la culture de ble. Les effets etaient plus importantes apres deux passages perpendiculaires (densite des plantes divisee par environ 2) que par un seul passage. En depit de l'eclaircissement, les rende-ments du ble n'ont pas ete reduits par le hersage d'automne grâce a une compensation par le poids de 1000 grains. La biomasse d'ete de S. media et G. aparineetait plus reduite par un hersage de printemps que d'automne, alors que la biomasse de B. napus n'etait reduite que par un hersage d'automne. Les especes grimpantes et faible-ment enracinees sont done plus facilement com-battues par des travaux de printemps, alors que celles qui presentent un racine pivotante sont plus facilement combattues par un hersage d'automne, a un stade precoce. Die Wirkung verschieden haufigen Eggens im Herbst oder im Fruhjahr auf Wintenveizen und auf die Bekampfung von Stellaria media (L.) Vill., Galium aparine L. und Brassica napus L. Eggen im Herbst mit einer beweglichen Zinkenegge verringerte die Dichte von Stellaria media (L.) Vill., Galium aparine L. und Brassica napus L. und reduzierte den Weizenbestand. Die Wirkungen waren durch 2 Arbeitsgange im rechten Winkel zu einander, wobei der Pflanzenbestand ungefahr halbiert wurde, gegenuber einer einzelnen Bearbeitung ver-starkt. Aufgrund eines ausgleichenden Anstiegs des Tausendkorngewichts wurden die Weizenertrage trotz Ausdunnung der Bestande nicht durch Eggen im Herbst reduziert. Die Sommerbiomasse von S. media und G. aparine wurde mehr durch Eggen im Fruhjahr als durch Eggen im Herbst verringert, wahrend die Biomasse von B. napus nur durch Eggen im Herbst reduziert wurde. Daraus folgt, das schwach wurzelnde und kletternde Arten einfacher durch Eggen im Fruhjahr bekampfbar sind, Arten mit einer Pfahlwurzel besser im Herbst zu einem fruheren Entwicklungsstadium.

Summary Weeds were collected from carrot fields and some other sites at 27 localities in seven counties in Norway during August and September of 1986 and 1987. Leaf and petiole lesions were microscopically examined for Mycocentrospora acerina. Viola arvensis and Viola tricolor were commonly observed with the pathogen. The fungus was also registered on Fumaria officinalis, Galium aparine, Matricaria inodora, Matricaria matricarioides, Ranunculus repens, Senecio vulgaris and Stachys palustris. In inoculation experiments in the greenhouse, M. acerina infected carrot leaves and 13 of 16 species of weeds. The symptoms on the various susceptible plants showed some variation, but were essentially of the same pattern. The investigation indicates that weeds are common hosts of M. acerina. A list of 23 host weed species is given.

Extracts of culture filtrate of the phytopathogenic fungus Alternaria alternata (Fries) Keissler cause distinct wilting of cuts of the problem weed Galium aparine L. We were able to demonstrate that the cyclic tetrapeptides tentoxin and dihydrotentoxin were reponsible for this effect. A tentoxin derivative, isolated from the culture filtrate, shows a similar, but stronger wilting activity.

summary The techniques of architectural analysis were applied to the root systems of plants growing under field conditions, to determine their validity in this situation and to measure the extent and causes of plasticity and of interspecific differences in root architecture in co-existing species. In a three-year study of two species (Trifolium repens L. and Plantago lanceolata L.) on eleven different soils, large differences were found between species, soils and years; much of the variation in the root architecture of T. repens could be explained in terms of soil moisture concentration. On two woodland sites, the root architecture of five species was followed over a 15–month period, and at one a manipulative experiment involving irrigation and nitrogen and phosphorus addition was set up. There were large differences between species in root architecture and seasonal changes in some aspects (topology and exterior link length), which probably represent developmental patterns. Irrigation induced topological changes in one species (Galium aparine L.) which were consistent with the results of the three-year study, but not apparently with an earlier model. In the case of Mercurialis perennis L., however, both irrigation and N and P addition brought about the predicted changes in root architecture, namely shorter interior links and lower topological index, though N had the opposite effect on exterior links. Interior link length differed widely between species, but showed little temporal variation, suggesting that it may be a valuable character for further studies. These results illustrate the validity and potential of architectural analysis for the study of root systems extracted from field soils.

Summary Seedbanks and seedling emergence, resulting from seeds shed in wheat crops and ploughed in, were monitored in two experiments for 3–4 years in successive autumn sown crops, in which herbicides were used to prevent re-seeding. Populations of Galium aparine, Papaver rhoeas, Lamium purpureum, Myosotis arvensis, Veronica persica, Viola arvensis and Veronica hederifolia were studied in separate plots. The numbers of viable seeds in the soil declined exponentially; G. aparine and V. hederifolia declined most, and P. rhoeas and V. arvensis least rapidly. Total weeds (all species) over the 3–4 years, (obtained by adding successive numbers of seedlings recorded in each autumn or winter), represented 3–4% of the first year seedbank for the combined species. Few seedlings emerged in the first year after seeding due to effective burial by the initial ploughing. The species showing the greatest emergence in the first year, relative to seedbank size, were G. aparine and V. hederifolia. Other, smaller seeded, species produced their main seedling flushes in the second and third years after seeding. It is concluded that poor weed control in one year is likely to result in large weed infestations for up to four years and probably longer for some species.

Summary: In 962 field trials in different crops, the size of a number of weed species was investigated. The weeds were ranked according to their size on a single occasion. The ranks of the species were examined relative to two weed species, Viola arvensis and Matricaria inodora. The ranking was, however, independent of which of the two species were used as standard. The correlation between the rankings with Viola arvensis as standard, and the rankings with Matricaria inodora as standard were r= 0-93 for spring sown crops, and r= 0.84 for autumn sown crops. Sinapis arvensis was the largest weed species in spring sown crops, with a weight of 14.5 times that of Viola arvensis, followed by Brassica napus, Galeopsis spp., Thlaspi arvense and Amsinckia spp. Viola arvensis. Veronica spp. and Lamium spp. were the smallest weed species in spring sown crops. Galium aparine was the largest species in autumn sown crops, whereas spring germinating species such as Polygonum spp. were among the smallest. The ranks of Viola arvensis, Myosotis arvensis, Lapsana communis, Matricaria inodora and Lamium spp. were almost identical in spring sown crops and in autumn sown crops. Resume: Dans 962 essais de plein champ dans differentes cultures, l'importance du nombre d'especes d'adventices a eteetudiee. Les adventices etaient classees en fonction de leur nombre sur une simple circonstance. Lesclasse ments des especes etaient examinees par rapport a deux especes, Viola arvensis et Matricaria inodora. Le classement etait, cependant, independant de celui des deux especes utilisees comme standards. La correlation entre les classements avec Viola arvensis comme standard et ceux avec Matricaria inodora comme standard etait de r= 0,93 pour les cultures de printemps, et r= 0,84 pour les cultures d'automne. Sinapis arvensisetait I'espece la plus importante dans les cultures de printemps avec un poids 14,5 fois plus grand que Viola arvensis, suivie de Brassica napus, Galeopsis spp., Thlaspi arvense et Amsinckia spp. Viola arvensis, Veronica spp. et Lamium spp. etaient les especes les moins importantcs dans les cultures de printemps. Galium aparineetait l'espece la plus importante dans les cultures d'automne, tandis que les especes germant au printemps comme Polygonum spp. etaient les moins importantes. Les quantites de Viola arvensis, Myosotis arvensis, Lapsana communis, Matricaria inodora et Lamium spp., etaient sensiblement identiques dans les cultures de printemps et d'automnes. Zusammenfassung: In 962 Feldversuchen in verschiedenen Kulturen wurde die Grose einer Anzahl Unkrautarten untersucht. Die Einordnung der Arten wurde entweder auf Viola arvensis oder auf Matricaria inodora bezogen. Die Korrelation zwischen Einordnungen nach Viola arvensis als Standard und solchen nach Matricaria inodora betrug r= 0,93 fur Sommerungen und r= 0,84 fur Winterungen. Sinapis arvensis war die groste Art in Sommerkultured Indem Gewicht 14,5mal so gros wie das von Vtola arvensis war, gefolgt von Brassica napus Galeopsis spp., Thlaspi arvense und Amsinckia spp.; Viola arvensis, Veronica spp. und Lamium spp. waren die kleinsten Unkrautarten. In Winterkulturen war Galium aparine die groBte Art, wahrend im Fruhjahr gekeimte Arten wie Polygonum spp. zu den kleinsten zahlten. Die Grosen von Viola arvensis, Myosotis arvensis, Lapsana communls, Matricaria inodora und Lamium spp. waren zwischen Sommer- und Winterkulturen so gut wie gleich.

The herbicide diflufenican is an effective pre-emergence compound used for the control of ‘difficult’ dicotyledonous weeds in winter cereals. It is less efficient when applied post-emergence, activity being found to depend on the dose reaching the apical meristems. Contact with diflufenican had no significant effect on other parts of the plant and translocation was negligible. In the absence of surfactants, the uptake of diflufenican was minimal and complete approximately 2h after treatment. Surfactant incorporation increased the time over which uptake occurred, efficiency depending on surfactant type and lipophilicity. ‘Silwet L-77’ (1.0 g litre−1) was the only surfactant tested which caused sufficient damage to the apex to prevent subsequent recovery of the plant. The effect of nonylphenol ethoxylate surfactants at concentrations above the critical micelle concentration (

Galium aparine L. und Galium spurium L. unterscheiden sich qualitativ nur in der Blutenfarbe. Wenn diese nicht zur Verfugung steht, kann die Unterscheidung durch eine mehrdimensionale Varianzanalyse mil funf quantitativen Merkmalen erfolgen, die im Einzelvergleich nur selten eine Artentrennung zulassen. Die anhand sicher bestimmter Individuen gewonnenen Merkmalswerte ergaben eine lineare Diskriminationsfunktion, mit deren Hilfe Herbarbelege sicher klassifiziert werden konnten. Galium aparine L. and Galium spurium L. differ qualitatively only in the color of flowers. If the flower color can not be observed, a differentiation is possible by a multivariate analysis of variance using five quantitatives characteristics which as singles very seldom allow to distinguish these species. The values of characteristics obtained from exactly determined individuals result in a linear discriminant function for a sure classification of herbarium material.

The following are extended summaries based on posters presented at the 8th International Congress of Pesticide Chemistry (IUPAC), held in Washington, DC, USA 4–9 July 1994. They are entirely the responsibility of the authors, and do not necessarily reflect the views of the Editorial Board of Pesticide Science.

Resume: Summary: Zusammenfassung L'estimation du Potentiel sernencier a ete faite sur 50 Parcelles de grande culture de Co-d'Or. Dans des sols de texture argileuse a sableuse. Le Potentiel semencier mesure sur 30 cm de hauteur, varic de 400 a 86 500 semences par metre carre, avec une moyenne de 11 600 et une mediane de 5100 semences par metre carre. Par station on a denombre en moyenenne 21 especes, les especes les plus frequentes sont Alopecurus myosuroides, Anagallis arvensis, Capsella bursa pastoris, Chenopodium album et Kickxia spuria. La viabilite moyenne des semences extraites du sol est estimee a 82,7% avec des fortes variations selon les epeces, de 31% chez Veronica hederifolia a 99% chez Chaennorhinum minuss ou Sonchus asper, mais il n'a pas ete possible de verifier si les graines qui n'ont pas germe sont profondement dor-mantes ou mortes. Le potentiel semencier du sol est un meilleur estimateur de la presence des mauvaises herbes dans les parcelles cultivees que les levees au champ, sauf pour des especes a grosses graines, comme Avena fatua ou Galium aparine. Weed seed banks of arable fields The weed seed content of arable fields was determined for 50 clayey to sandy soils of the Cote-d'Or. The weed seed bank in the 0–30 cm soil layer varied from 400 to 86 500 seed m-2 with an average of 11 600 and a median of 5100 seeds m-2. The mean number of species by field was 21 and the most frequent species were Alopecurus myosuroides, Anagallis arvensis. Capsella bursa pastoris, Chenopodiun album and Kickxia slpuria. The mean viability of the buried seeds was 82·7%, with a large range between species, from 39% for Veronica hederifolia to 99% for Chaenorrhinum minus of Sonchus asper. It was not possible to determine if the ungerminated seeds were deeply dormant or dead. The seed bank is a better indicator of the frequency of weeds in arable fields than the actual flora, except for large seeded species such as Avena fatua of Galium aparine. Der Unklrautsamenvorral in Ackerboden In 50 tonigen bis sandigen Boden der Cote-d'Or wurde der Gehalt an Unkrautsamen bestimmt, Der Samenavorrat in der Bodenschicht van 0–30 cm Tiefe variierte zwischen 400 und 86 500 Samen m-2, bei einem Durchsehnitt von 11 600 und einem Medianwert von 5100 Samen m-2. Im Mittel waren pro Feld 21 Arten vertreten; am haufigsten wurden gefunden: Alopecurus myosuroides, Anagallis arvinsis, Capsella bursa pastoris, Chenopodium album und Kickxia spuria. Durchschnittlich waren 82,7% der Samen lebensfahig, wobei grosse Differenzen zwischen de Arten festgestellt wurden. Veronica hederifolia wies cine Keimfahigkeit von 36% auf. Wahrend diese bei Chaemorrhinum minus oder Sonchus asper bei 99% lag. Es war nicht moglich festzustellen job die ungekeimten Samen tot oder vollig dormant waren. Der Samenvorrat im Boden ist ein besscrer Indikator fur die Hafigkeit von Unkrautern als die bestehende Flora; eine Ausnahme bilden grossamige Arten wie Avena fatua oder Gulium aparine.

Zusammenfassung Verschiedene geographische Herkiinftc innerhalb Bayerns von fiinf Ackcrunkraularlen wurden auf ihre Eignung als Wirtspflanzen des Rubenzysten-alchens Heterodera schachtii Schmidt untersucht. Dabei forderten die Wurzeldit Tusaie siimtlicher geprufler Herkunlte von Capsella bursa-pasforis und Stellaria media den Larvenschlupf aus Zys-ten; Chenopodium album-. Viola arvensis- und Galium aparinc-Hcrkunflc wirkten neutral. Bei erstgenannten Artcn konnten ini Biotest regel-maBig Zyslenneubildungen fcslgcstelll werden, wahrend an den Wurzein von Chenopodium album nur vcreinzell. an denen von Viola arrensis und Galium aparine in keinem Fall frische Zysten gebildel wurden. Auch hinsichllieh des Einflus.ses aufdie Populationsdichtc (Pf/Pi-Wert = Quotient aus Endverseuehung und Ausgangsvcrseuchung) tralen keine Untersehiede auf. Die Wirtseignung einer Unkrautspezies gegeniiber Heterodera achachtli stellt somit, zumindesl innerhalb eines begrenzten geographischen Raumcs, eine artspe-zifisehe Eigenschafl dar. Summary Investigations on the suitability of weeds of various geographical origins as hosts of the sugar-beet nematode Heterodera schachtii Schmidt The suitability of five weed species of various geographical origins in Bavaria as host plants of Heterodera schachtii was tested. The root diffusates of all Capsella bursa-pastoris and Stellaria media origins examined increased hatching of larvae; Chenopodium album. Viola arvensis and Galium aparine did not have any effects. In biotests, cyst-forming was found regularly on the first-mentioned species, whereas only single ones were seen on the roots of Chenopodium album, in no case were new cysts found on those of Viola arvensis and Galium aparine. There were also no differences in influence on the population density. Hence, at least within a restricted geographical area, the suitability of weeds as hosts of Heterodera schachtii is species-specific. Resume Investigations sur la capacitea heberger le nematode de la betterave (Heterodera schachtii Schmidt) chez les mauvaises herbes d'origines geographiques differentes L'aptitude d'origines geographiques differentes de cinq especes d'adventices a heberger Heterodera schachtii a ete testee. Les seeretats racinaires de toutes les origines examinees de Capsella bursa-pastoris et Stellaria media augmentent la sortie des larves; les origines de Chenopodium album, Viola arrensis et Galium aparine n'ont pas d'effets. Dans des tests biologiques, la formation de kystes a ete observee regulierement sur les premieres especes mentionnees, tandis que les racines de Chenopodium album seulement quelques individus etaient concernes et pour Viola arvensis et Galium aparine aucun kyste n'a ete trouve. Il n'y a pas non plus de differences dues a l'influence sur la densite de population. De la au moins dans une zone geographique limitee, la capacite des adventices a heberger Heterodera schachtii est une propriete inherente a l'espece.

Summary Weeds in a total of 450 fields of winter oilseed rape in nine areas of central southern England were surveyed, just prior to harvest during summer 1985, to identify those that had survived herbicide treatment or had not been sprayed and, thus, were capable of re-infestation or contamination of the harvested crop. Sixty-two species were identified; their levels of infestation were scored and distribution within the field noted. The most frequent species was Galium aparine, which occurred in 57% of fields. Mayweeds (Tripleurospermum inodorum, Matricaria recutita and Anthemis cotula) occurred in 23% of fields and Papaver rhoeas in 21%. All other species occurred in less than 20% of fields, the most prevalent being Sonchus asper(18%). Grassweeds were relatively infrequent, reflecting the widespread use of effective graminicides; the most prevalent was Arena spp., found in 9% of fields. Although most species were distributed throughout the field, Geranium dissection (13%) and Sisymbrium officinale (7%) were virtually confined to field margins (extending 1 m into the crop) and headlands (10m into the crop), respectively. Several species exhibited a well-defined regional distribution; Silene alba was virtually restricted to the most southern counties surveyed, whilst Papaver rhoeas and Viola arvensis were conspicuously absent from the eastern area. Resume Releve des mauvaises herbes presentes dans les cultures de colza de la region Centre-Sud de l'Angleterre Dans 450 champs de colza d'hiver, situes dans 9 zones de la region Centre-Sud de l'Angleterre, on a opere des releves de mauvaises herbes juste avant la recolte de l'ete 1985, pour identifier celles qui avaient survecu aux traitements herbicides, ou qui, n'ayant pas ete traitees, etaient donc capables de reinfester ou de contaminer la recolte. Soixante deux especes ont ete identifiees; on a estime leurs niveaux d'infestation et note leur distribution dans les champs. L'espece la plus frequente etait Galium aparine, presente dans 57% des champs. Tripleurospermum inodorum, Matricaria recutita ou Anthemis cotulaetaient rencontres dans 23% des champs et Papaver rhoeas dans 21%. Toutes les autres especes se trouvaient dans moins de 20% des champs, la plus repandue etant Sonchus asper (18%). Les graminees etaient relativement peu frequentes, en raison de l'utilisation repandue de graminicides efficaces; la plus frequente etait Avenu spp., trouvee dans 9% des champs. Quoique la plupart des especes etaient distribuees sur toute la surface des champs. Geranium dissectum (13%) et Sysymbrium officinale (7%) etaient confines respectivement aux bordures (sur une largeur de I m) et aux tournieres (10 m a l'interieur de la culture). Plusieurs especes etaient nettement distribuees selon les regions; Silene alhaetait en pratique restreint aux comtes les plus meridionaux, alors que Papaver rhoeas et Viola arvensisetaient manifestement absents de la region Est. Zusammenfassung Verbreitung von Unkratern in Raps in Sud-England Im Sommer 1985 wurde kurz vor der Ernte die Unkrautflora von 450 Rapsfeldern im mittleren Sud-England aufgenommen, um herauszufinden, welche Arten die chemische Bekampfung uberstanden hatten oder nicht bekampft worden waren und deshalb zu erneuter Verunkrauterung oder Verunreinigung des Ernteguts fuhren konnten. Es wurden 62 Arten gefunden; ihre Dichte und Verteilung auf den Feldern wurden aufgenommen. Die hafigste Art war Galium aparine, das auf 57% der Felder auftrat. Kamillen (Tripleurospermum inodorum, Malricaria reculila, Anthemis cotula) wurden auf 23%, Papaver rhoeas auf 21% der Felder gefunden. Alle anderen Arten traten auf weniger als 20% der Felder auf, dabei Sonchus asper auf 18%. Graser waren relativ selten, worin sich der verbreitete Einsatz von wirkungsvollen Graminiziden widerspiegelt; am hafigsten waren noch Avena spp. mit 9%. Wahrend die meisten Arten uberall auf den Feldern gefunden wurden, war das Vorkommen von Geranium dissectum (13%) und Sisymbrium officinale (7%) deutlich auf die Feldrander (bis I m Breite) und die Vorgcwende (bis 10 m) beschrankt. Verschiedene Arten zeigten eine bestimmte regionale Verbreitung; Silene alba trat nur im assersten Suden auf, Papaver rhoeas und Viola arvensis fehlten auffallig im Osten.

Four plant community types are described for Oland's Stora Alvar, the limestone plateau of South Oland and preliminary classified syntaxonomically: (1) Crepis pumila – Allium alvarense ass. (2) Helianthemum oelandicum – Galium oelandicum ass. (3) Gypsophila fastigiata – Globularia vulgaris ass. and (4) Veronica spicata – Avenula pratensis ass. (with two subassociations, the Sedum reflexum and Galium boreale subass.). The ecology of these types is discussed with emphasis on soil depth, frost perturbation and the combined effects of summer drought and grazing intensity. Various endemic taxa appear to be good character species for the community types described. The typical local ecology of some common species is discussed with the suggestion that they might have formed endemic ecotypes which should be further investigated. The communities described are very rich in cryptogams. The floristic variation as expressed by the cryptogamic species composition shows largely the same pattern as that shown by the phanerogams.