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Context: Polygala myrtifolia L. has become a significant environmental weed in Australia, where it has invaded coastal ecosystems in temperate regions and there is a high risk of extensive further spread. Knowledge of seed-germination behaviour is essential to understand the potential future impact of this species. Aims: We investigated the effects of selected environmental factors and dormancy on P. myrtifolia seed germination and emergence to improve management strategies. Methods: Seeds were exposed to light, temperature, pH, salinity, osmotic potential and burial depth treatments to assess germination responses, dormancy and viability. Key results: Non-dormant seeds readily germinated to high percentages (93.0–95.0%) under specific day–night temperatures of 25°C–15°C regardless of light conditions and across all soil pH (75.0–100.0%). Salinities were tolerated up to 100 mM NaCl (70.0% germination) before sharply declining. Germination reduced from 98.3% to 40.0% at osmotic potentials of −0.4 MPa and −0.6 MPa respectively. Emergence was greatest on the soil surface (48.33%) and absent from depths of 8 cm. Conclusions: Germination was high during autumn, winter and spring conditions and across soils of any pH. The species is unlikely to invade areas of high salinity; however, it is moderately tolerant of low soil moisture during germination. Implications: There is high risk of P. myrtifolia further invading sensitive ecosystems because of its high germination success. Preventing seed dispersal and ensuring seedlings are controlled on emergence are critical to reducing its impact. We recommend that the cultivation and sale of this species should be prohibited across Australia to prevent further spread. Polygala myrtifolia has become a significant environmental weed in Australia, where it has invaded coastal ecosystems in temperate regions. This study assessed the effects of selected environmental factors on its seed germination, which was optimal for untreated seeds under a 25°C–15°C temperature range, regardless of light conditions. Germination was inhibited under increasing salinity, moisture stress and burial depth. To prevent further spread, P. myrtifolia infestations should be actively managed by preventing seed dispersal and controlling emerging seedlings. [ABSTRACT FROM AUTHOR]

The objective of this study was determining the effectiveness of weed control and increasing the productivity of the DN Galatea corn hybrid when using modern herbicides, plant growth regulators and adjuvants. Indicators of the technical efficiency of herbicides differed according to the variants of the experiment, which generally characterizes the phytotoxic properties of the agents as a different indicator. At the initial stage of the development of the corn agrocoenosis, the highest efficiency was provided by: Task Extra(880g/ha) + Synergen SOC(0.25%) – 92%; Titus Extra(50 g/ha) + Synergen SOC(0.15%) – 39%; Titus Extra(100 g/ha) + Synergen SOC (0.25%) – 94%; Titus Extra(50 g/ha) + Prima(0.4 L/ha) + Synergen SOC(0.15%) – 94%. As can be seen from the figures, the corn crops in those variants were free of weeds during the phases of panicle shedding. Effective control of the invasion of weeds in corn, but with lower technical efficiency options, was demonstrated by Task Extra (440g/ha) + Trend 90 (0.1%) – 85%; Task Extra (440g/ha) + Synergen SOC (0.15%) – 89%; Titus Extra (50 g/ha) + Trend 90 (0.2%) – 86%; Titus Extra (100 g/ha) + Trend 90 (0.2%) – 88%. The application of the Master Power (1.5 L/ha) – 70% also caused a less significant effect; this was not the first year we observed this. Based on the results of the research in our laboratory, we can conclude that the Master Power is significantly inferior to the herbicide Master (150 g/ha) + Biopower (1.25 L/ha), which was more effective. The highest above-ground biomass of weeds in the air-dry state was traditionally recorded in the control version without the introduction of the agents – 109.7 g/m2. The characteristics of the weed flora on the research plots are also given, as well as the evaluation of the elements of the structure of the corn hybrid crop with the use of the specified agents.

Context: Peatlands in the Australian Alps are important ecologically and recognised in national environmental legislation. Increasing fire frequency over the past 40 years has put the community at greater risk of degradation. Aims: Using published studies of fire effects in peatlands and new data, we investigate general responses of peatlands to fire so that risk can be evaluated and appropriate management adopted. Methods: We present four case studies that employ repeated measures of floristic composition or chronosequences to assess fire-related changes. Key results: Cover of frequently-occurring species declined after fire but most had returned to pre-fire cover after 10 years. Recovery of the obligate seeder shrub Dracophyllum continentis (B.L.Burtt) S.Venter and the dominant moss Sphagnum cristatum Hampe was much slower, but variable for the latter, apparently depending on fire intensity and post-fire moisture availability; both species favoured less frequently burnt peatlands with high soil moisture. Some herbs (including non-native species) benefitted from fire, briefly becoming abundant soon afterwards. Overall species richness and diversity were unaffected by fire. Conclusions: Peatlands in the Australian Alps tend to be resilient to single fires with effects on species composition being short-lived. However, species cover (especially Sphagnum cristatum) requires perhaps 20 years between fires for full recovery. Fire can cause localised community extinction and this is likely to be exacerbated by other pressures such as trampling and drought. Implications: Fire will be difficult to manage in peatlands but resilience might be built by removing other pressures such as trampling by feral animals. Peatlands of the Australian Alps are important ecologically and recognised in conservation legislation but they are increasingly threatened by fire. Our review of long-term studies in peatlands shows that species composition recovers within a few years of fire but species cover, including the dominant moss layer, does not. A fire frequency less than 20 years may cause permanent change in this plant community but resilience might be enhanced by removing other threats, in particular trampling by feral animals. Photo credit: Keith McDougall. [ABSTRACT FROM AUTHOR]

Cotton is a sensitive crop for the agronomic practices. Therefore, in this experiment two levels of wheat straw mulch (0 and 4.2 t ha-1) and two different plant spacing (25 and 35 cm), applied on three cotton varieties; Lachata, Coker 310 and Stoneville 213 which were to investigate growth traits and also controlling of weeds, pests, insects and diseases. Thus, the results showed that Lachata variety required fewest days from planting to 50 % flowering and boll opening that were 57.83 and 145.66 days respectively. While, lowest and highest height of first fruiting branch were recorded by Coker 310 and Stoneville 213 (11.55 and 13.13 cm), respectively. In addition, the interaction of factors also was significantly affected NODF and HFFB such as in V2S1M1 by (68.33 days and 13.73 cm). The treatments applied by wheat straw mulch have more vigorous cotton plants and less infected by weeds, insect, pests and diseases as compared to no mulch. The researchers must conduct more experiments to determine the effect of straw mulch on growth of cotton by using different rates.

Globally, many species and ecosystems are experiencing landscape-scale wildfires ('megafires') and these events are predicted to increase in frequency and severity as the climate warms. Consequently, the capability to rapidly assess the likely impacts of such large fires and identify potential risks they pose to the persistence of species and ecosystems is vital for effective conservation management. In this review, we propose novel frameworks to identify which plant species and ecosystems are most in need of management actions as a result of megafires. We do this by assessing the impacts of a fire event on plants and ecosystems in the context of the whole fire regime (current fire event combined with recent fire history) and its interactions with other threatening processes, rather than simply considering the amount of habitat burnt. The frameworks are based on a combination of key species' traits related to mechanisms of decline, components of the fire regime that are most likely to have adverse impacts on species or ecosystem recovery, and biotic and environmental factors that may amplify fire impacts or pose barriers to post-fire recovery. We applied these frameworks to guide management priorities and responses following the extensive 2019/2020 fires in southern Australia, and we illustrate their application here via a series of worked examples that highlight the various mechanisms of post-fire decline the frameworks address. The frameworks should be applicable to a broader range of fire-prone biomes worldwide. Our approach will (1) promote the development of foundational national datasets for assessing megafire impacts on biodiversity, (2) identify targeted priority actions for conservation, (3) inform planning for future fires (both prescribed burning and wildfire suppression), and (4) build awareness and understanding of the potential breadth of factors that threaten plants and ecosystems under changing fire regimes. The occurrence of large-scale fires is increasing globally. Adverse impacts of these fires on plants and ecosystems can be significant without rapid management responses. We developed novel predictive frameworks to identify the species and vegetation types in most urgent need of post-fire intervention to promote successful recovery after such megafires. The frameworks described here are applicable to major fire events in a diverse range of biomes across the world. [ABSTRACT FROM AUTHOR]

Other herbicides, alone or in combination with glyphosate, may be effective in controlling Richardia brasiliensis, Commelina benghalensis, Conyza sumatrensis e Digitaria insularis. Therefore, the aim of this study was to evaluate the efficacy of herbicides, alone or in combination, in the control of these weeds in the off-season. Three composite experiments were conducted by applying herbicides, alone or in combinations. Experiments 1 and 2 were conducted in Palotina, State of Paraná (PR), Brazil. Experiment 3 in Iporã, PR, Brazil. The three during fall 2017 in fallow areas after soybean harvest. The experiment was a randomized complete block design with 4 replications and weed control at 7, 14, 21, 28, 35, and 42 days after application (DAA). The control of R. brasiliensis and C. benghalensis was evaluated in the three experiments, the control of C. sumatrensis, in experiments 1 and 2, while the control of D. insularis was evaluated only in experiment 3. Data were subjected to analysis of variance and F-test (p < 0.05). The treatment means values of experiments 1 and 2 were compared by Tukey’s test (p < 0.05), and the treatment mean values of experiment 3 were grouped by the Scott and Knott test (p < 0.05). Some herbicide combinations were effective in controlling R. brasiliensis, C. benghalensis, in a single or sequential application. Herbicide combinations were effective in controlling C. sumatrensis with sequential application. Herbicide combinations in a single application did not provide satisfactory final control (≥ 80%) for D. insularis.

Ecological communities are increasingly being recognized as the products of contemporary drivers and historical legacies that are both biotic and abiotic. In an attempt to unravel multiple layers of ecological contingency, we manipulated (i) competition with exotic annual grasses, (ii) the timing of this competition (temporal priority in arrival/seeding times) and (iii) watering (simulated rainfall) in a restoration-style planting of native perennial grasses. In addition, we replicated this experiment simultaneously at three sites in north-central California. Native perennial grasses had 73-99 % less cover when planted with exotic annuals than when planted alone, but this reduction was greatly ameliorated by planting the natives 2 weeks prior to the exotics. In a drought year, irrigation significantly reduced benefits of early planting so that these benefits resembled those observed in a non-drought year. There were significant differences across the three sites (site effects and interactions) in (i) overall native cover, (ii) the response of natives to competition, (iii) the strength of the temporal priority effect and (iv) the degree to which supplemental watering reduced priority effects. These results reveal the strong multi-layered contingency that underlies even relatively simple communities.

Ecological communities are increasingly being recognized as the products of contemporary drivers and historical legacies that are both biotic and abiotic. In an attempt to unravel multiple layers of ecological contingency, we manipulated (i) competition with exotic annual grasses, (ii) the timing of this competition (temporal priority in arrival/seeding times) and (iii) watering (simulated rainfall) in a restoration-style planting of native perennial grasses. In addition, we replicated this experiment simultaneously at three sites in north-central California. Native perennial grasses had 73-99 % less cover when planted with exotic annuals than when planted alone, but this reduction was greatly ameliorated by planting the natives 2 weeks prior to the exotics. In a drought year, irrigation significantly reduced benefits of early planting so that these benefits resembled those observed in a non-drought year. There were significant differences across the three sites (site effects and interactions) in (i) overall native cover, (ii) the response of natives to competition, (iii) the strength of the temporal priority effect and (iv) the degree to which supplemental watering reduced priority effects. These results reveal the strong multi-layered contingency that underlies even relatively simple communities.

Containment is a frequently advocated strategic objective for countering plant invasions. It is commonly perceived that it is the valid fall-back option when eradication has failed or is deemed impossible with the available resources. We reviewed management and research literature on containment. The lack of a clear, universally accepted definition of containment is problematic and containment practice is not well aligned with the limited research literature. Vague and inconsistent use of the term, poorly developed relationships between management practice and the ecological drivers of invasion, and frequent failure to specify appropriately scaled spatial configurations in management strategies make it difficult to evaluate containment as a strategy, generally or in specific cases. Management strategies rarely provide the basis for effective and efficient containment programs and this may reflect a lack of under-pinning scientific principles. We recommend that containment be defined as ' deliberate action taken to prevent establishment and reproduction of a species beyond a predefined area ' and suggest that containment efforts should focus on individual infestations or populations but simultaneously cover all infestations or populations that are separated from one another by habitat suitable for the species. Containment units should be rigorously defined but the inevitability of breaches of these containment units, due to the stochastic nature of dispersal, implies that containment generally requires a capacity for local eradication (extirpation). This means that many infestations are no more amenable to containment than to eradication. The measures we propose would improve assessment of the feasibility and success of containment strategies. When weeds invade an area, containment is often seen as the best fall-back option if eradication seems impossible. We examined extensive management and research literature and concluded that containment is currently poorly defined and no easier to achieve than eradication. We offer a clear definition and outline how the feasibility and success of containment strategies can be better assessed. [ABSTRACT FROM AUTHOR]

The risk posed by invasive alien species is determined primarily by two factors: distribution (occupancy) and abundance (density). However, most ecological studies use distribution data for monitoring and assessment programs, but few incorporate abundance data due to financial and logistical constraints. Failure to take into account invaders' abundance may lead to imprecise pest risk assessments. Since 2003 as part of the Annual Pest Distribution Survey (APDS) exercise in the state of Queensland, Australia, government biosecurity officials have collected data on distribution and abundance of more than 100 established and emerging weeds. This data acquisition was done at spatial grid sizes of 17–50 × 17–50 km and across a very broad and varied geographical land area of ~2 × 106 km2. The datasets provide an opportunity to compare weed dynamics at large-medium spatial scales. Analysis of the APDS datasets indicated that weed distributions were highest in regions along the southern and central, coastal parts of Queensland, and decreased in the less populated inland (i.e. western) and northern parts of the state. Weed abundance showed no discernible landscape or regional trends. Positive distribution–abundance relationships were also detected at multiple spatial scales. Using both traits of weed abundance and distribution, we derived a measure of invasion severity, and constructed, for several (64) weed species, 'space-for-time' invasion curves. State-wide and in each of Queensland's 10 regions, we also categorised the invasion stages of these weeds. At the grassroots of local government area or regional levels, the derived invasion curves and stage categories can provide policy direction for long-term management planning of Queensland's priority weeds. We examined distribution and abundance of major weeds in Queensland, Australia, and constructed invasion curves at intermediate–lower spatial scales. Our work provides the first state-wide and regional-level invasion stage-categorisation, and spread patterns of weeds in Queensland. The findings serve as input into policy, management and research directions of Queensland's prioritised weeds. [ABSTRACT FROM AUTHOR]

This study reviews published information on the tactical management decisions needed to maximise economic grain yield in winter-dominant rainfall regions of the Mediterranean type. Tactical decisions are defined as those relating to the period from immediately before sowing to harvest. Tactical management is the principal means by which farmers respond to changing environmental and short-term economic conditions as the season progresses. The review considers published evidence that underpins these decisions and relates to cereal crops (wheat, barley and oats), pulse crops (field pea, faba bean, chickpea and narrow-leaved lupin) and canola. The criteria used to guide management decisions during the season involve soil and tissue tests for nutrients, knowledge of weed numbers and resistance status in the current and previous seasons, weather conditions that favour disease development, and knowledge of thresholds and biology of insect pests that may warrant control measures. All of these decisions can be related to the timing of the opening rains and the length of the growing season; the crop, pasture or weeds present in the previous two seasons; the presence of pest- and disease-bearing crop residues; and the type of tillage in use. Most of these indicators require further refinement through research across environments, soil types, crop types and production systems. The likely interactions between tactical or short-term management decisions, longer term or strategic decisions, and genetic factors are discussed. The prevalent use of chemicals in the management of biotic factors that can impact the crops is noted, as is progress towards various systems of 'integrated' management of these threats to crop production. Most tactical decisions in rainfed cropping systems appear to be supported by adequate evidence, although some decisions are still based on practical experience and observations. Application of tactical management practices together with strategic management and use of improved genotypes provides the possibility of achieving rainfall-limited potential grain yield at a regional scale. The papers reviewed have been selected partly on the basis that the experimental treatments achieved the estimated potential grain yield. Where the potential grain yields are not being achieved in commercial crops, it remains unclear whether this is due to inadequate adoption of existing information or inadequate research to identify and address the underlying causes. We highlight the need to devise a simple decision aid to assist farmers and their advisers to respond to the variable seasonal conditions evident since the turn of the Century. Rainfed climate across the world have always been variable but the variability both within and between seasons has increased. Consequently, crop producers must adjust their management practices at sowing time and during the season to avoid crop failures and to utilise fully the rain that does fall. This review confirms that short-term or in-season decisions are major contributors to yield improvement, but that they need to be further supported by practical research. [ABSTRACT FROM AUTHOR]

Livestock grazing has been used for conservation management in some situations to reduce exotic plant cover, but supporting empirical evidence is scant. This is particularly true for eastern Australian semiarid woodlands and forests. We surveyed 451 sites across three broad semiarid vegetation communities (cypress pine, black box, red gum) in eastern Australia to examine the effects of recent and longer-term (historic) grazing by livestock on exotic (and native) plant cover. Because our focus was the use of domestic livestock for conservation management, our sites were mostly located in conservation reserves, travelling stock routes and native production forests where domestic grazing is approved via permit. We also included recent grazing by kangaroos and rabbits, which occur widely with livestock across the study sites. Structural equation modelling revealed that recent sheep and cattle grazing was associated with increased exotic plant cover in two of the three communities (cypress pine, black box), and historic grazing was associated with lower exotic (and native) plant cover across all communities. Recent cattle grazing-induced reductions in exotic plant cover in the red gum community resulted from declines in the palatable exotic annual grass Ehrharta longiflora. Higher intensity grazing by rabbits, sheep and cattle in the cypress pine community increased exotic plant cover by suppressing the negative effect of native cover on exotic cover. Higher intensity rabbit grazing reinforced the negative effect of nitrogen on native plant cover, resulting in increases in exotic cover. Overall, we found strong evidence that domestic livestock grazing reduces native plant cover either directly or indirectly in all three communities, but limited evidence that it would be a useful conservation management strategy to reduce exotic plant cover in these communities. Livestock grazing has been used for conservation management in some situations to reduce exotic plant cover, but supporting empirical evidence is scant. We found strong evidence that domestic livestock grazing reduces native plant cover either directly or indirectly in three extensive woodland communities, but limited evidence that it would be a useful conservation management strategy to reduce exotic plant cover. [ABSTRACT FROM AUTHOR]

The genetic variability and genetic versatility of plants belonging to Poaceae provide morphophysiological responses that allow these individuals to adapt to environmental changes, especially in relation to soil moisture. Urochloa plantaginea and U. platyphylla are grasses typical of dry environment, also found as weeds in rice fields, where there are high amounts of water in the soil. The objective of this work is to analyze the development of these two species in different environments, subjecting them to three different amounts of water in the soil. Morphological parameters were analyzed in order to verify and quantify which suffered alteration with respect to water variation. Caryopsis of the two species were collected in a commercial irrigated rice crop. Seeds were sown in pots containing a substrate-sand system, and housed in a greenhouse, where during the experiment the control of different moisture contents (shallow water table, 100% of field capacity and 50% of field capacity) took place. Weekly evaluations were carried out according to the parameters analyzed. The following parameters were evaluated: duration of the vegetative and reproductive life cycle, number of the inflorescences per plant, number of branches per inflorescence, number of spikelets per branch, number of seeds per plant, and dry mass production. The U. plantaginea cycle had shorter duration under the shallow water table, while for U. platyphylla the shorter duration was under the condition 50% of field capacity. Both species produced higher dry mass of shoots under the condition of 100% of field capacity. The main responses observed for both species, due to the flooding, were the change of the cycle, reduced dry matter production, and reduced seed production.

Differences in plant biomass/plant seed production relationship imply that plants suppressed by competition to the same extent, may not suffer the same reduction in seed number setting. This size-dependent process evidenced by the quantitative relationship between plant growth and allocation to reproductive structures can be considered from an allometric perspective. The aim of this study was to describe the reproductive allometry of four annual weed species of the Pampas cropping systems by modelling the plant biomass/plant seed production relationship in Digitaria sanguinalis , Amaranthus hybridus , Setaria verticillata and Chenopodium album. To achieve this goal, two experiments developed during two consecutive growing periods (Experiments 1 and 2) were set up under greenhouse conditions. Weed species were grown in monocultures and in binary mixtures, with each other and with soybean crop, to obtain plants of different size after the effect of intra and interspecific competition. Data per plant regarding biomass versus seed number production considering monocultures and mixtures from Experiments 1 and 2 were analysed for each species using linear regression. Parameters of the linear functions fitted for C. album , S. verticillata and D. sanguinalis did not differ between experiments and data were pooled. Thus, three single specific models were obtained with the same intercept of zero (y -axis intercept when x = 0 was zero) and different slopes, 1122, 69 and 130 seeds g plant biomass–1 respectively. In the case of A. hybridus , the slopes were different in Experiments 1 (123 seeds g plant biomass–1) and 2 (74 seeds g plant biomass–1). Moreover, reproductive allocation changed allometrically under highly competitive stress since small plants failed to set seeds, unless a plant biomass threshold was attained (x -axis intercept when y = 0 was positive). Besides the ecological interpretation in reproductive output, implications in weed management are considered. Quantitative relationship between plant growth and allocation to reproductive structures was allometrically studied in four annual weed species. Linear regressions fitted for plant biomass/seed number relationships in Digitaria sanguinalis , Setaria verticillata , Chenopodium album and Amaranthus hybridus differed consistently in the pattern of reproductive allocation given by the slope of the models. The linear models fitted for the first three species had the same intercept close to zero (y -axis intercept when x = 0 was zero). Distinctly, Amaranthus hybridus reproductive allocation changed allometrically under highly competitive stress since small plants failed to set seeds, unless a plant biomass threshold was attained (x -axis intercept when y = 0 was positive). [ABSTRACT FROM AUTHOR]

Some species are used as cover crops, so they can produce and release products from their secondary metabolism. When these products are released in the environment, they are exposed to direct or indirect influences. Thus, this trial aimed to evaluate the influence of soil moisture content in plant decomposition, possibly caused by allelochemicals release. The influence of soil field capacity was evaluated by the decomposition of black oats (Avena strigosa Schreb), turnip (Vicia villosa Roth) and hairy vetch (Raphanus sativus L.) residues, with 70 and 50% of water availability and the control. Pots (1.0 kg) were filled with sterilized and unsterilized soil, plus 30 g of plant residue, which remained in decomposition for four weeks before the experiment start. After that, five seeds of beggartick (Bidens pilosa L.) were sowed and seedling emergence was daily evaluated for 10 d. The emergence speed index and emergence speed were calculated. Five seedlings were transplanted at the 8th d and evaluated during 30 d, to obtain the initial development of plants, and to determine fresh and dry mass. Greatest growth inhibition of the weed tested occurred with 70% available water for plant emergence and with 50% for initial plant development.

The presence of Araujia sericifera Brot. (Apocynaceae) in the vascular flora of central Chile is reported for the first time. A morphological description and an illustration is provided, as well as a background about its habitat, ecology and phenology.

The long-term exploitation of natural resources by agricultural activities has resulted in the need for alternative measures to restore degraded soil. The cultivation of cover crops can generate great benefits for agricultural systems, enabling the exploitation of natural resources, including water, light and nutrients, as well as the recovery of degraded soils. This work aimed to assess the coverage rate, fresh mass and dry mass of cover crops from fall and winter as well as the floristic composition of the weeds. The work was conducted in field conditions in soil classified as eutroferric Red Oxisol in the region of the city of Palotina, Paraná State, Brazil, using a random block experimental design with four replications. The treatments consisted of seven cover cultures: wild radish, linseed, triticale, rye, rapeseed, crambe, oats and fallow. The species with the highest coverage rates and fresh mass and dry mass values were wild radish, rapeseed and crambe. In the floristic and phytosociological data, the species with the highest incidence were Amaranthus retroflexus, Commelina benghalensis L., Brachiaria plantaginea and Gnaphalium spicatum.

This study aimed to evaluate the ingestive behavior and physiological responses of steers under different grazing conditions. Five Nellore steers, weighing an average of 390.78 ± 14 kg BW, were assigned to five experimental treatments: clean pasture without concentrate supplementation (PLSC), dirty pasture without concentrate supplementation (PSSC), clean pasture with concentrate supplementation (PLCC), dirty pasture with concentrate supplementation (PSCC) and free access to pasture without concentrate supplementation (LAPSC). The experimental design was a 5 x 5 Latin Square. The grazing behavior was measured through visual observation at the end of each trial in ten-minute intervals for 24 hours, and the physiological variables comprised rectal temperature, respiratory rate and heart rate. The physiological responses of animals were not affected by treatments. The number of steps performed by the animals kept in treatments PLSC (6.08 steps/min) and PLCC (5.62 steps/min) were significantly lower than those in treatments PSSC (16.84 steps/min) and PSCC (14.58 steps/min), showing increased activity of locomotion in animals in paddocks with weeds.

Cover crops can offer significant advantages in the agronomic management of citrus orchards in Mediterranean environments. Therefore, a three-year research was conducted in eastern Sicily aimed at studying the effects of four cover crop sequences (Sinapis arvensis-Trigonella foenum-graecum-T. foenum-graecum; Medicago scutellata-Avena sativa-Lolium perenne; Vicia faba minor-A. sativa-A. sativa; A. sativa-V. faba. minor-L. perenne) on weeds, major soil chemical properties and nutritional status of an organically grown orange orchard. The results highlighted that, among the studied cover crop sequences, Vicia faba-Avena-Avena was the most beneficial for weeds control within the orchard (92%, of cover crop cover, and 586 and 89 g DW m–2 of cover crop aboveground biomass and weeds aboveground biomass, respectively). Overall, the chemical fertility of the soil was positively influenced. In particular, it was observed an increase of the content of total nitrogen and available phosphorus in the soil by both Sinapis-Trigonella-Trigonella (0.75 g kg–1 and 59.0 mg kg–1, respectively) and Vicia faba-Avena-Avena (0.70 g kg–1 and 56.0 mg kg–1, respectively) cover crop sequences. Medicago-Avena-Lolium sequence seemed to be the most useful to ensure a better nutritional status of the orange orchard.

The main issue that European agriculture is facing is related to maintaining and if possible increasing yields while reducing inputs - especially pesticides, including herbicides. Society is paying increasing attention to the quality of products as well as to the sustainability of the productive system. Control of weeds is necessary to achieve economically acceptable yields. The main tool is chemical weed control. This practice spread quickly after its introduction, due its efficacy and simplicity, but it also generated a series of agronomic and environmental issues. One of the solutions to maintain yields, while reducing herbicide use is the adoption of the Integrated Weed Management (IWM). IWM is based on the knowledge of weeds and their response to cropping practices, weed-crop competitive relationships and chemical and non-chemical means of control. IWM has had a quite remarkable success among researchers, politicians and public opinion, but has rarely been applied by farmers. The limited implementation of this management approach may have different explanations: i) IWM is more complex than conventional management as it requires greater skill and is more time consuming; ii) there is a lack of financial support and demonstration farms, necessary to convince the farmers to adopt it; iii) IWM is considered riskier than conventional management; iv) research has not succeeded in transferring scientific knowledge to the productive systems.The paper includes an analysis of several examples of IWM application in Italy in recent years (development of decision support systems, predictive models, formation of GIRE (Italian Herbicide Resistance Working Group) with the objective of defining their benefits and drawbacks and finding new solutions for the future. It is also underlined that the main difficulty in IWM development is the lack of integration between means of control and proactive agronomic practices that are suitable to prevent the spread and evolution of weeds in the fields.

In order to predict the potential agronomic scenarios of the future, the probable involvements of climatic changes on weed dynamics were analyzed. In this perspective the several climatic parameters were examined and overlapped to the biological characteristics of the different species to predict both: weed evolution and the sustainability of the relative management. Thermal and CO2 increasing favour the weed ruderality in terms of seed quantity and velocity of seed set. In addition the increasing of stress factors (thermal, drought, UV-B, etc.) favour the de-specialization trend as typically occurs in the most persistent weeds. Adverse climatic dynamics, even due to events of opposite biological action (for example drought and flooding), appears to have a synergistic impact with the agronomic disturbances. Indeed these additive disturbances increase the selective pressure of the phytocoenoses and play a crucial role in the allowing survival only to the “segetal” weeds as well it occurs from the origin of agriculture. Consequently, the different degree of resilience induces a decreasing of the phytocoenoses complexity. This biodiversity reduction appears to increase the risk of exotic weed invasion overall regards to species from warmer and more arid environments (potentially even parasite species). Their invasivity could be increased by biotic or abiotic stress factors that are not present in their native environment. The fate of rare weeds appears to go to their extinction, overall if their dynamics is linked to fragile mutualistic interaction as it occurs in the case of entomogamous species. Indeed such simultaneous presence (flora and pollinator fauna) is mined by the progressive differences between photoperiod and thermoperiod and the consequent de-synchronization of their phenological phases. This virtual weed evolution through the increasing of the richness of self- and wind-pollinated weeds will involve both: 1) the agricultural landscape degradation; 2) a worse human health because of atmosphere rich of allergenic pollen. In conclusion, weed phytocoenoses appear to be less vulnerable of the relative crops to the climatic injuries. This higher crop vulnerability will increase the pesticides use as well as already predicted regards to entomologic and phytopatologic aspects. Finally, an agronomic strategy of the future was hypothized. This is based on the germplasm utilization of the wild types in order to increase the environmental crop plasticity in the predicted climatic scenarios.

Research about phytotoxic activity of natural compounds could lead both to find new herbicidal active ingredients and to plan environmental friendly weed control strategies. Particularly, living organisms could be a source of compounds that are impossible, for their complexity, to synthesize artificially. More over, they could have alternative sites of action respect to the known chemical herbicides and, due to their origin, they should be more environmental safe. Many living organism, such as bacteria, fungi, insects, lichens and plants, are able to produce bioactive compounds. They generally are secondary metabolites or simply waste molecules. In this paper we make a review about these compounds, highlighting potential and constraints.

Aim To use herbarium records to characterize important correlates of spatial spread, areal occupancy and clustering of 100 alien plant species of conservation concern in the North and South Islands of New Zealand. Location New Zealand. Methods Using herbarium data of 6294 records representing 100 alien plant species, we assessed spatial heterogeneity in the distribution of alien species by examining the role of major urban areas as sources of sampling bias. A novel method to account for spatial biases in sampling effort was developed and applied to two simple distance metrics: nearest- and furthest-neighbour spread rate. The relative importance of these two distance metrics in determining the range, areal extent and dispersion of alien species across both the North and South Islands of New Zealand was also assessed. Results The spatial distribution of herbarium records was highly clustered with a significant bias towards the more populated regions. Once sampling bias was taken into account, there was no indication that species were found closer to these urban centres than might be expected based on sampling effort. The nearest-neighbour spread rates were usually 1–5 km yr−1 and correlated positively with the furthest-neighbour spread rates that were an order of magnitude higher. Range and area increased and clustering decreased with higher spread rates and longer recording time span. The spread rates divided species into five groups that were clearly distinguishable in terms of the extent of their distribution and the degree of clustering. Species occurring on both islands did not exhibit similar spread rates or spatial patterns. Main conclusions The nearest- and furthest-neighbour spread rates from herbarium records can explain the area and pattern of alien plant distributions and improve the understanding of the dynamics of their spread. Five groups emerge from the spread rates in relation to a null model. Fast-spreading plants had the widest, least clustered distribution, which suggests widespread chronic problems; slow-spreading plants had localized, but dense, clustered distributions, indicating acutely problematic weeds. These patterns appear robust and may be useful in predicting the future patterns of spread and in planning long-term management strategies in New Zealand. [ABSTRACT FROM AUTHOR]

Worldwide, invasive weeds threaten agricultural, natural and urban ecosystems. In Australia's agricultural and grazing regions, invasive species often establish across extensive areas where weed management is hampered by an inability to detect the location and timing of an outbreak. In these vast landscapes, an effective detection and monitoring system is required to delineate the extent of the invasion and identify spatial and temporal factors associated with weed establishment and thickening. In this study, we utilize a time series of remote sensing imagery to detect the spatial and temporal patterns of Prickly Acacia ( Acacia nilotica) invasion in the Mitchell grass plains of North Queensland. We develop a spectral index from Landsat images which is applied to images from 1989 to 2004, in combination with a classification mask, to identify locations and monitor changes in Prickly Acacia density across 29 000 km2 of Mitchell grass plains. The approach identified spectral and temporal signatures consistent with Prickly Acacia infestation on 1.9% of this landscape. Field checking of results confirmed presence of the weed in previously unrecorded locations. The approach may be used to evaluate future spread, or outcomes of management strategies for Prickly Acacia in this landscape and could be employed to detect and monitor invasions in other extensive landscapes. [ABSTRACT FROM AUTHOR]

Direct seeding methods to revegetate abandoned farmland were tested at a desert site west of Phoenix, Arizona. Native seeds were broadcast onto plots prepared by mulching, imprinting, chiseling, and fertilizing with phosphorous in a split-plot design. Each main plot was split into subplots that were not irrigated, irrigated with saline (3.25 dS/m) well water, or irrigated and hand weeded of Salsola iberica. Native seeds germinated poorly on all treatments, and three annual exotic weeds (Brassica nigra, S. iberica, and Schismus spp.) dominated the plots. None of the main plot treatments (mulching, imprinting, chiseling, or fertilizing) had a significant effect on seed germination or canopy cover. Irrigation increased plant cover on plots, but weeds dominated the cover (<4% native species, up to 50% weeds). Near the end of the second growing season a seed bank study was conducted in the greenhouse. Undisturbed desert soil had relatively few weed seeds and more native plant seeds than the disturbed agricultural soil samples, which had few viable native seeds and were dominated by Schismus spp., B. nigra, and S. iberica. The results illustrate the difficulty of establishing native plants on abandoned desert farmland due to the dominance of weedy species, the presence of salts in the soil, and the lack of adequate soil moisture in the treatments without supplemental irrigation. [ABSTRACT FROM AUTHOR]

The main models within the MILDRI modelling network for studying plant protection, PVNOR, a dynamic model which simulates the development of weeds and diseases in cereals, and FARMNOR, an economic analysis model for choosing and evaluating management practices, were used to predict the effect of different production systems on the need for plant protection measures, and the resulting yield and economic output in different climatic situations. The simulations were run for 22 years using historic weather data. The study showed that PVNOR reflected fairly well the changing plant protection problems and agricultural consequences which emerged during the simulation period, and that the model handled the interactions between the large number of variables involved in such perennial systems. The combination of PVNOR and FARMNOR proved to be a valuable analytical tool, which in addition to predicting plant protection problems and consequences, also allows the prediction of the economic outcomes arising from different cereal production systems. [ABSTRACT FROM AUTHOR]

A list of 618 species of alien flowering plants recorded for Mexico is presented; they are distributed in 355 genera and 87 families. The families with the largest number of species are Poaceae (171), Fabaceae sensu lato (57), Asteraceae (56), and Brassicaceae (45). The representation of most families with alien species in Mexico agrees with the average distribution frequencies estimated by ) for 26 floras throughout the World. Exceptions are an under-representation of Asteraceae and an over-representation of Poaceae. Most alien species (78.9%) in Mexico have their origin in the Old World; South America ranks second with 9.6%. As defined by ), 19.8% of the alien species could be considered casual aliens and 80.2% of them naturalized. The proportion of alien species relative to the 22,968 native flowering plant species recorded for Mexico is 2.7%. [ABSTRACT FROM AUTHOR]

Fresh Sida spinosa L. seeds do not imbibe water and germinate because the seed coat is impermeable to water. Seeds imbibe water when a portion of the coat in the chalzal area separates from an underlying layer of subpalisade cells. Thin-waited subpalisade cells are limited to the area beneath the chalazal area, Palisade cells in the coat region that become permeable are tall, only lightly lignified, contain abundant hemicellulose and have large cell lumena. Palisade cells in regions of the coat that remain impermeable to water are short, have heavily lignified thick walls, small cell lumena and are tightly packed. We propose that Sida spinosa seed coat dormancy is released when moisture eventually reaches the hygroscopic hemicellulose deposits in cell lumena in the lightly lignified palisade cells of the chalazal region. The subsequent expansion of the palisade cells causes the thin-walled subpalisade cells to break, resulting in separation of palisade from subpalisade cells and free passage of water through the exposed surface to the embryo, culminating in germination. [ABSTRACT FROM AUTHOR]

I. Itch grass Rottboellia cochinchinensis is a serious weed in the humid tropics However, the seed bank is short-lived (approximately 3 years) and control methods that effectively prevent inputs to the seed bank should have a long-term impact on the weed. The head smut Sporisorium ophiuri. which forms systemic infections sterilizing the weed, has therefore been proposed as a potential classical biological control agent. 2. A difference equation model of the population dynamics of the weed R. cochichinesis was developed for a maize cropping system. The model was used to estimate the constant annual infection rate by the S. ophiuri that would be necessary to provide long-term control of the weed. 3. The model suggested that with the smut as the sole control agent, an annual infection rate of about 88% would be required to reduce R. cocchinensis density to 10% of the level achieved with no control. 4. However, when combined with one or two weedings per year, the level of infection necessary for satisfactory control could be reduced. Since the maximum infection rate achieved in experiments was about 80%, the smut is unlikely to achieve satisfactory control when used alone, but these results suggest that S. ophiuri could be a useful adjunct in integrated control programmes. 5. The extent to which the effectiveness of the smut was improved by combining it with weeding depended on the seed set in the R. cochinchinensis flush emerging after weeding and on seedling mortality. Where seed set or seedling survival were low, the required infection rate could be substantially reduced. 6. These results are discussed in the context of future prospects for biological control of R. cochinchinensis and areas for further research to improve the utility of the population dynamic model are highlighted. [ABSTRACT FROM AUTHOR]

Light, probably acting through the photoreceptor phytochrome, promotes germination of weed seeds when the soil is disturbed by tillage operations. A short period of burial is shown to induce an enormous &ap;10000-fold increase in light sensitivity in the seeds of the arable weed Datura ferox which is interpreted as a natural transition to the 'very-low-fluence' mode of Phytochrome action. Field experiments indicated that germination of buried seeds may be triggered by milli-second-exposures to sunlight and suggested a key role for the process of sensitization in the mechanisms whereby light requiring seeds detect the occurrence of soil cultivation events in arable lands. [ABSTRACT FROM AUTHOR]

Interactions between parasitic angiosperms and their hosts occur at the level of seed germination, haustorial development and resource transfer. Chemicals released from the host function as cues for host recognition, and trigger germination as well as haustorial initiation. Transpiration is a key process regulating solute transfer from host to parasite, and some parasitic plants have unusual stomatal characteristics. Although solute transfer is apoplastic, the haustorium appears to play a role in regulating solute composition. Host responses to infection are reviewed, and it is concluded that competition for water and solutes are unlikely to play a major role in determining reductions in host productivity; metabolic incompatability is suggested to be the major cause of this. [ABSTRACT FROM AUTHOR]