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1.
Fluazifop-butyl, haloxyfop and sethoxydim with adjuvant oil were applied for three successive growing seasons to established strawberries infested with Elymus repens. The weed was virtually eradicated by three applications of haloxyfop (0.8 kg a.e. ha?1) in successive years. A similar effect was given by five applications of haloxyfop (0.4 kg a.e. ha?1) and fluazifop-butyl (1.6 kg AI ha?1) in three growing seasons. Lower rates of haloxyfop and fluazifop-butyl, and a high rate of sethoxydim (1.6 kg AI ha?1) applied five times were less effective, the ground cover of E. repens shoots not being reduced by the end of the experiment although weight of living rhizome was only 10-30% of that on untreated plots. Fruit yields on treated plots generally reflected the level of E. repens control, but there was some evidence of crop phytotoxicity from herbicide treatments. During the experiment E. repens untreated plots increased from about 30-100% ground cover and reduced yield 13, 28 and 68% in successive years compared with weed-free plots.  相似文献   

2.
为研究间作功能植物对茶园主要害虫茶小绿叶蝉的影响,于2017—2018年在福建省泉州市安溪县茶园间作白三叶Trifolium repens L.、金花菜Medicago hispida Gaertn.、金盏菊Calendula officinalis L.,以自然留养杂草茶园为对照,用网捕法采集茶小绿叶蝉并于室内计数,镜检剥查法调查其茶梢着卵量。结果表明,在4种不同生境管理茶园网捕茶小绿叶蝉总个体数及每月个体数均无显著差异;茶小绿叶蝉个体数分别在2017年8月与2018年6月达到高峰。茶梢各节间着卵量不同,主要产卵在顶芽之下第2～5节间,以第4节着卵量最多。间作金盏菊茶园茶小绿叶蝉在茶梢第1节着卵量显著高于间作白三叶和金花菜茶园。不同生境管理茶园茶小绿叶蝉在茶梢第4节着卵量从大到小依次为间作金盏菊(8.13)、间作金花菜(7.50)、自然留养杂草(7.17)和间作白三叶茶园(6.57)。不同时间段4种不同生境管理茶园茶小绿叶蝉在茶梢各节之间的着卵量存在差异,且均在9月上中旬着卵量达到高峰。在茶园间作功能植物,短期内未见其显著降低茶小绿叶蝉网捕量和茶梢着卵量的效应。  相似文献   

3.
The semiaquatic plants, S agittaria trifolia and S agittaria pygmaea, are perennial and troublesome weeds of rice paddy fields. These species mainly reproduce vegetatively via tubers, which sprout after the rice paddy fields are irrigated. Sprouting finally leads to the emergence of the shoots from the water in the paddy fields. In both species, the first internode elongates around the time of emergence and this lifts the shoot meristems in the soil, aiding in the establishment of the young plants. Therefore, elongation of the internode is a factor that determines the weed damage to rice caused by these species. In this study, the first internode elongation of both species was characterized. During emergence, S . trifolia and S . pygmaea showed distinct growth patterns. In S . trifolia, the internodes elongated before the emergence of the shoots from the water; whereas, in S . pygmaea, the internodes started to elongate only after emergence. We examined environmental prerequisites for internode elongation, and found that the internode elongation of S . trifolia was induced by submergence and was independent of the soil cover, while that of S . pygmaea required both submergence and covering. Next, we determined which gaseous factors were responsible for internode elongation. Treatment with ethylene, which enhances growth of several other aquatic and semiaquatic plants, did not stimulate internode elongation in either species under an anaerobic condition. Our results suggested that the gaseous factor stimulating internode elongation in S . trifolia and S . pygmaea may be oxygen depletion and carbon dioxide, respectively.  相似文献   

4.
Mechanical weed control of perennial weeds in organic crop production over long post‐harvest periods is incompatible with the establishment of cover crops for improving soil quality and preventing nutrient leaching. We suggest a new concept that comprises uprooting and immediate removal of vegetative propagules located within the plough layer to allow for quick re‐establishment of a plant cover. A field experiment comparing the effects of conventional practices (stubble cultivation) with different combinations of rotary cultivation (One, Two or four passes) and cover crops (none vs. rye‐vetch‐mustard mixture) on Elytrigia repens rhizome removal, shoot growth and suppression of a subsequent barley crop was examined in two growing seasons. Four passes with a modified rotary cultivator, where each pass was followed by rhizome removal, reduced E. repens shoot growth in barley by 84% and 97%. In general, the cover crop developed poorly and did not affect barley or E. repens. Barley yield was only affected by treatments in the first season, where yield was negatively correlated with E. repens shoot biomass. The concept has potential for the control of severe E. repens infestations, but future research aimed at identifying more effective smother crops and less intensive methods of rhizome removal is needed.  相似文献   

5.
Developing invasive plant management strategies is an important task in modern ecology, conservation biology and land management. Solidago gigantea is considered a problematic invader in Europe and Asia, where it forms dominant stands that can decrease species diversity. There is, therefore, an urgent need for effective management to reduce S. gigantea infestations and their negative impacts. We examined the efficacy of multiple approaches to S. gigantea management in Hungary. In our study, we evaluated the effect of several long-term management techniques such as grazing, mowing and periodic flooding on the invader's density as well as native community diversity. In addition, we investigated the short- and long-term effects of mowing combined with other treatment options, to estimate the influence of increased management intensity. Our results indicate that all tested management techniques had negative impacts on S. gigantea density. Short-term mowing did not appear to improve species diversity in the resident community; however, all long-term options improved species diversity. Moreover, combining treatments with mowing varied in its effectiveness; mowing once increased the efficacy of flooding, but decreased the efficacy of grazing, while mowing twice decreased efficacy of flooding. We suspect this is due to the increased intensity of disturbance, which does not allow for the natural recovery of communities, and after management ceases, invasion is able to re-occur. Our results indicate that for effective management, we need to combine management options which act via different mechanisms, leading to cumulative positive effects on the resident community when applied at moderate levels.  相似文献   

6.
Stemphylium vesicarium, the causal agent of brown spot of pear, overwinters in the leaf residues of pear and herbaceous plants of the orchard floor. Pseudothecia of the teleomorph, Pleospora allii, are formed on these residues where they produce ascospores. New methods were tested aimed at reducing this overwintering inoculum and increasing the efficacy of control of brown spot of pear. Sanitation methods were evaluated in nine trials in Girona (Spain) and Ferrara (Italy) over a 4-year period. The sanitation methods were leaf litter removal in December to February, and application of biological control agents (commercial formulates of Trichoderma spp.) to the orchard ground cover from February to May. Fungicides were also applied to the trees during the pear-growing season, scheduled according to the BSPcast model. The different methods were tested as stand-alone applications or in combination. All methods consistently reduced the disease incidence at harvest on fruit with an efficacy between 30 to 60% for leaf litter removal and more than 60% for the combination of leaf litter removal and biological control. Efficacy of sanitation alone (leaf litter removal and biological control) in reducing the brown spot level on fruit was similar in most of the trials to the efficacy obtained when fungicides were applied alone. However, integration of sanitation methods and fungicides did not improve the efficacy of disease control over the level provided by fungicides alone.  相似文献   

7.
K French  E Watts 《Weed Research》2015,55(6):537-545
To investigate the impact of invasion by Chrysanthemoides monilifera ssp. monilifera (boneseed) on plant communities, sites that were invaded and uninvaded were surveyed across Tasmania, South Australia and Victoria, Australia. Above‐ground cover abundance was estimated and samples of the seed bank from invaded and uninvaded sites in each state were collected and germinated in the glasshouse. We compared species richness and composition between invaded and uninvaded sites for both above‐ground and below‐ground samples. Across this broad geographic area, C. monilifera invaded sites had 25% fewer species than uninvaded sites and twice as many exotic species. Most growth forms showed reduced richness in invaded sites. There were no differences in the composition of native species communities between invaded and uninvaded sites in most regions, except South Australia. The composition of the seed bank differed from the above‐ground vegetation, but was similar within each state. Herbs and grasses were most abundant. The species composition of the seed bank was different in invaded sites only in Victoria, suggesting that invasion may negatively influence the capacity of the seed bank to restore vegetation in some areas. However, the underlying mechanisms for the observed patterns were not tested in this study. The capacity of all sites to regenerate effectively from the seed bank was limited and, in order to ensure the conservation of biodiversity into the future, monitoring of species richness at smaller scales, particularly those where management of C. monilifera has occurred, will be needed to ensure management can facilitate the establishment of missing species. This study suggests that C. monilifera impacts a range of functional groups and different species across its distribution and is therefore non‐selective in how it influences changes in communities.  相似文献   

8.
Docks can be serious weeds of arable land and permanent grasslands where they can persist through well‐established root systems. A Rumex hybrid (R. patientia x R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in Czechia and has now become a new weed species. As its ecological characteristics are unknown, there is a need for improved knowledge for developing control measures and strategies. In 2010 and 2011, we performed a tube pot experiment to investigate above‐ground and below‐ground biomass growth dynamics and below‐ground biomass allocation of Rumex OK‐2. We compared the hybrid with Rumex crispus and Rumex obtusifolius during the vegetation season in the seeding year. Above‐ground and below‐ground biomass of Rumex species tended to increase from July to September. In the seeding year, flowering was recorded only for one plant of Rumex OK‐2 and 27.5% of R. obtusifolius plants, whereas R. crispus did not flower. The proportion of below‐ground biomass of Rumex species in the upper 30 cm was about 70–80%. The growth dynamics and allocation of below‐ground biomass of Rumex OK‐2 were more like R. crispus than to R. obtusifolius. These similarities indicate the potential of Rumex OK‐2 to become a troublesome weedy species, comparable with R. crispus.  相似文献   

9.
Invasion by alien species is a serious threat to the biodiversity and function of semi‐natural grasslands and may impede restoration efforts in degraded meadows due to high competitiveness. Goldenrods (Solidago and Euthamia species) are considered among the most injurious invaders of grasslands in Central Europe. We tested the hypothesis that native grass species are able to outcompete the invasive goldenrods. A replacement series experiment was established to determine levels of interference between native grass taxa and goldenrods. In the experiment, four alien goldenrod species (Solidago altissima, Solidago canadensis, Solidago gigantea and Euthamia graminifolia) and one native species (Solidago virgaurea) were studied. The native grasses were represented by Lolium perenne (forage and turf varieties) and Festuca pratensis (forage variety). Total biomass was higher in the mixture of species compared with that in monoculture. The higher total biomass was due to higher productivity of the goldenrod species, whereas that of the grasses was reduced. These results demonstrated the high competitiveness of alien goldenrods compared with native grass species.  相似文献   

10.
Strigolactones, plant‐secreted underground signalling molecules, play an important role in agricultural ecosystems, because they mediate the interaction of crops with symbiotic AM fungi and parasitic weeds like Striga hermonthica. Cereal host plants secret these signalling molecules particularly under nutrient‐deficient conditions and especially when phosphate (P) is limiting. The objective of the present study was to see the potential of P seed priming for S. hermonthica management in cereals in relation to strigolactone production. It has been demonstrated that P fertiliser application down‐regulates the production of these signalling molecules in the rhizosphere, which results in lower S. hermonthica infection of cereals. The laboratory study showed maximum production of strigolactones from dry and water‐soaked seeds, while seed soaking in P solution reduced their production. Similarly, maximum S. hermonthica infection was observed under control treatments with dry sowing or water soaking, while P seed soaking decreased S. hermonthica germination, emergence and dry biomass in all cereal crops. Our study shows that P seed priming resulted in lower exudation of strigolactones, which induced less S. hermonthica seeds germination and hence may lead to lower S. hermonthica infection. P‐based seed priming could prove to be an effective and affordable strategy to reduce S. hermonthica infection in cereals. Further research for practical field application is needed.  相似文献   

11.
Two potential control methods for Elymus repens, which do not disturb the soil, are post‐harvest mowing and competition from under‐sown cover crops. Our aim was to quantify the effect of cover crop competition and mowing on E. repens and to evaluate the potential for combining the two methods. We present a two‐factorial split‐plot experiment conducted at three locations in Sweden, in two experimental rounds conducted in 2011–2012 and 2012–2013. A spring cereal crop was under‐sown with perennial ryegrass, red clover or a mixture of the two (subplots). Under‐sown crops were either not mowed, or mowed once or twice post‐harvest (main plots). This was followed by ploughing and a new spring cereal crop the next year. Mowing twice reduced autumn shoot biomass by up to 66% for E. repens and 50% for cover crops compared with the control, twice as much as mowing once. Pure ryegrass and mixture treatments reduced E. repens shoot biomass by up to 40% compared with the control. Mowing twice reduced rhizome biomass in the subsequent year by 35% compared with the control, while the pure red clover treatment increased it by 20–30%. Mowing twice and treatments including red clover resulted in higher subsequent grain yields. We concluded that repeated mowing has the potential to control E. repens, but a low‐yielding cover crop has insufficient effect on rhizome biomass. Clover–grass mixtures are of interest as cover crops, because they have the potential to increase subsequent crop yield and even at low levels they reduce E. repens above‐ground autumn growth.  相似文献   

12.
Alien plants produce severe environmental and economic losses in the territories they invade. Modelling the spatial distribution of alien species as a function of the environment in the native range has therefore become an essential first step in the struggle against invasions. Phyla nodiflora var. minor is a fast‐growing perennial herb native to South America that has spread through three continents, where it poses a major threat to biodiversity and significantly impacts on conservation and grazing systems, mainly in riparian areas. To assess the distribution of native Argentine populations of P. nodiflora as a function of the environment, we conducted long‐term roadside surveys and associated the occurrence of the plant with climatic, geographical, demographical and vegetation cover variables in a generalised linear mixed model. The plant was recorded in 230 of 431 sites, mostly east of 66°W and north of 39°S. According to the best model, which predicted the data 58% better than random assignment, its occurrence was associated with temperature variables (mean annual values and daytime range) and relative humidity. Based on these associations, we generated a presence probability map for the occurrence of P. nodiflora in southern South America. Understanding the environmental determinants of the distribution of weeds in their native range provides valuable baseline data to further manage the spread of alien species.  相似文献   

13.
This study presents a list of invasive alien plants that are found along roadsides in seven selected European countries – Austria, Germany, the Netherlands, Ireland, Norway, Slovenia and Sweden – and an overview on the role of roadsides as a habitat for invasive alien plants. This compilation is based on national lists of invasive alien plants, a literature search and expert consultation. Comprising 89 species from 31 plant families, species introduced for horticulture dominate the list (65%). Thirteen species (14%) are widespread (occur in four or more countries) and include well‐known invasive plants such as Fallopia japonica, Heracleum mantegazzianum, Solidago canadensis and Solidago gigantea. Seventeen species are listed either on the EPPO List of Invasive Alien Plants or on the EPPO A2 List of pests recommended for regulation as quarantine pests. Five species are on the List of Invasive Alien Species of Union Concern (EU Regulation 1143/2014). The compiled list provides a snap‐shot of invasive alien plants currently found along roadsides in the selected countries. It allows for a more targeted approach to monitoring, containment and control of the most problematic invasive alien plants identified in each country. Moreover, the list may also be used to identify emerging (potentially) invasive alien plants along roadsides in other European countries that warrant monitoring and/or management.  相似文献   

14.
An investigation into the impact of Parthenium hysterophorus infestation was conducted in 2007 in the north‐eastern grazing lands of Ethiopia. Data on the above‐ground and seedbank species diversity were collected from five areas, each having sites with low, medium, or high levels of weed infestation. A total of 72 species was found in all areas. They were categorized into grass species (23), other species (48), or P. hysterophorus for ease of interpretation. A regression analysis showed a highly significant, but negative, relationship between the above‐ground species diversity and evenness with P. hysterophorus abundance. The mean cover abundance for the three infestation levels was 33.4% for P. hysterophorus, 41.0% for the grass species, and 26.5% for the other species. The most dominant grass species under all infestation levels were Cynodon dactylon, Urochloa panicoides, and Chloris gayana, while Andropogon abyssinicus and Eragrostis spp. were dominant under the low and medium infestation levels, respectively, and Hyparrhenia hirta was dominant under the low infestation level. Among the other species, Solanum nigrum was the most dominant under the low infestation level and Datura stramonium and Xanthium spp. were the most dominant under the medium and high infestation levels, respectively. The above‐ground dry biomass of P. hysterophorus increased between the low and high infestation levels, while that of the grass or other species reduced in the high, as compared to the low, infestation level. Although the grass species density decreased significantly with successive increases in the P. hysterophorus infestation level, no such trend could be seen for the other species. Within the soil seed bank, the viable seed density for the grass species, other species, and P. hysterophorus were 25.7, 5.8, and 68.5%, respectively. Similarly, the soil seed bank under the low‐, medium‐, and high‐infestation sites was dominated by P. hysterophorus, which contributed 25.1, 65.4, and 87.4% of the viable seed bank, respectively. Although the overall similarity between the above‐ground vegetation composition and the soil seed bank was low, it was similar at the low‐infested site. Thus, the invasion by P. hysterophorus was found to critically endanger the biodiversity of the grazing lands, particularly for the different grass and forbs species in the area. These changes might adversely affect not only future agriculture, but also food security, unless appropriate practises are developed and implemented for P. hysterophorus management.  相似文献   

15.
D. LANE 《Weed Research》1976,16(6):385-389
A survey of the composition and structure of the vegetation of the roadside easement and adjacent farmland was made at eighteen sites on the Mornington Peninsula. Victoria, Australia. The ground cover was grass dominant at all sites, with a predominance of introduced species notably Holcus lanatus, Anthoxanthum odoratum and Briza maxima. Agrostis tenuis and Paspalum dilatatum occurred to a lesser extent. Two alien broad-leafed species, Hypochoeris radicata and Plantago lanceolata, were abundant at most sites. The frequency of species present on the easement was markedly reduced in the adjacent farmland; conversely, the pasture plants Lolium perenne, Trifolium repens and T. subterraneum, did not colonize the easement to any great extent. At some sites, the native trees and shrubs had not been cleared during road construction. They were able to survive on the easement despite the influences of the adjacent road and farmland. Seedlings of all the native species were found.  相似文献   

16.
Elymus repens (L.) Gould and Agrostis gigantea Roth. 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 in E. repens and A. gigantea was 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 more E. repens growth than light intensities equal to those in a spring oat crop. E. repens raised from seeds and grown at light intensities equal to those found in a cereal crop, showed insignificant rhizome production.  相似文献   

17.
Increasing abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) in pastures and meadows in western Norway has caused reductions in forage yield and quality in recent decades. Understanding plant development and regrowth following cutting is essential in devising cost‐effective means to control rushes. In a field experiment in western Norway, we investigated development of above‐ and below‐ground fractions of rush from seedlings to three‐year‐old plants, including the impact on vigour of disturbing growth by different cutting frequencies during the period 2009–2012. Each year, the plants were exposed to one or two annual cuts or left untreated and five destructive samplings were performed from March to early December. Juncus effusus showed significantly more vigorous growth than Juncus conglomeratus in the last two years of the study period. The above‐ground:below‐ground biomass ratio of both species increased mainly in spring and early summer and was reduced in late summer and autumn. Removal of aerial shoots also reduced the below‐ground fraction of both species. One annual cut in July effectively reduced biomass production in both species by 30–82%, which was only a slightly smaller reduction than with two annual cuts, in June and August. Mechanical control measures such as cutting can thus effectively reduce rush vigour when performed late in the growing season.  相似文献   

18.
Chinese violet (Asystasia gangetica (L.) T. Anderson) is a perennial invasive weed belonging to Acanthaceae. Leaves of this weed have been suggested to possess phytotoxic activity. However, phytotoxic substances in this weed have not yet been reported. Therefore, the present study investigated phytotoxic activity of Chinese violet extracts and phytotoxic substances. The extracts of Chinese violet leaves inhibited the root and shoot growth of cress, lettuce, alfalfa, barnyard grass, ryegrass, and timothy, where the level of inhibition increased with increasing extract concentrations. Bioassay‐guided separations of the extracts led to isolation of two phytotoxic substances, indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol. Indole‐3‐carboxaldehyde significantly inhibited the root and shoot growth of cress at concentrations ≥100 and 30 μmol L?1, respectively, and concentrations of the substance required for 50% growth inhibition were 210 and 127 μmol L?1 for cress roots and shoots, respectively. The other substance, (6R,9S)‐3‐oxo‐α‐ionol, was reported to have strongly inhibited cress roots and shoots. The present results suggest that Chinese violet contains two phytotoxic substances indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol, and those substances may play an important role in the phytotoxic activity of Chinese violet.  相似文献   

19.
The aim of this study was to evaluate the in vitro efficacy of the combination of entomopathogenic nematodes and non-synthetic insecticides in the control of Nasutitermes spp. (Isoptera: Termitidae). Bioassays were performed upon insect collection from areas with the high incidence of this pest. The experimental arena for insecticide assays consisted of 80-mL plastic containers with a screened cover. We tested six insecticides and the nematode species Heterorhabditidis bacteriophora RS58, Steinernema glaseri RS38, and Heterorhabditis sp. isolates AL39, AL40, AL41, AL42, AL43, AL44, AL46, and AL47, all of which were grown in last-instar larvae of Galleria mellonella L. (Lepidoptera: Pyralidae). The insecticides Codipirol®, Pure Neem Oil®, and Pyroligneous Acid Extract® caused high mortality in adults of Nasutitermes. The nematode Heterorhabditis sp. AL40 presented a median lethal concentration of 7976 infectious juveniles per adult of Nasutitermes sp. In addition, the mixture of these three non-synthetic products at a concentration of 3% caused complete mortality in Heterorhabditis sp. AL40 and S. glaseri RS38. Future trials should be encouraged in order to evaluate the field efficiency of non-synthetic insecticides mixed or not with entomopathogenic nematodes.  相似文献   

20.
Farmers are recommended to employ mechanical control when Cirsium arvense is most sensitive to disturbance. Earlier studies suggest that this occurs at a stage of minimum below‐ground dry weight, coinciding with three to seven or seven to ten leaves per shoot, depending on the definition of below‐ground dry weight. However, some farmers notice better effects when mechanical control is performed at earlier leaf stages. To estimate the compensation point (CP), defined as the minimum weight of the entire below‐ground structure of C. arvense and to further understand links between initial root weight, planting depth and crop competition, three outdoor pot experiments were performed in Sweden in 2013‐2014. We hypothesised that (i) CP likely occurs before C. arvense has developed three leaves, (ii) relative depletion of the below‐ground system at CP is less at lower initial root weight compared with higher weight, and (iii) methodological variations in CP estimations have minor impact on the results. We found that the CP for C. arvense in all treatments occurred before shoots had developed three leaves and that treatment effects were minor (<0.5 leaf stages). Leaf and leaf stage definitions, choice of leaf range and model also had minor effects on CP estimates. Depletion of planted root fragments ceased around leaf stages 3‐4, and their partial replenishment also constitutes evidence for a CP at early leaf stages. For agronomy, our results imply that mechanical control of C. arvense should be performed earlier than previously recommended, probably before reaching an average of three to four leaves per shoot.  相似文献   

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