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1.
Meloidogyne graminicola is one of the most harmful organisms associated with rice cultivation throughout the world. Until recently, M. graminicola was present only in Asia, parts of the Americas, Madagascar and South Africa. In 2016, it was detected for the first time in mainland Europe (Northern Italy) and subsequently added to the EPPO Alert List. In this study, the risk posed by this nematode to rice in Italy was assessed using an internationally developed pest risk analysis scheme. In the risk assessment section, information about biology, pathways for entry, the likelihood of establishment, spread and negative impact of M. graminicola are reviewed. Internationally, its spread is more likely through the movement of infested host plants, soil or growing medium and non-host plant parts that may have growing medium attached, from areas where this nematode occurs. Migrant waterbirds, machinery and travellers were also considered as possible pathways for entry. The probability of establishment is very likely due to the suitable environmental conditions and the large range of host plant species present in Italy. This and the nematodes’ ability to survive for long periods in low oxygen environments make the control of M. graminicola very difficult. 相似文献
2.
ABSTRACT The Karnal bunt pathogen, Tilletia indica, is heterothallic and depends on encounters on wheat spikes between airborne secondary sporidia of different mating types for successful infection and reproduction. This life history characteristic results in reduced reproductive success for lower population densities. Such destabilizing density dependence at low population levels has been described for a range of animals and plants and is often termed an Allee effect. Our objective was to characterize how the Allee effect might reduce the invasive potential of this economically important pathogen. We developed a simple population model of T. indica that incorporates an Allee effect by calculating the probability of infection for different numbers of secondary sporidia in the infection court. An Allee effect is predicted to be important at the frontier of an invasion, for establishment of new foci by a small population of teliospores, and when the environment is nonconducive for the production of secondary sporidia. Using estimated model parameter values, we demonstrated a theoretical threshold population size below which populations of T. indica were predicted to decline rather than increase. This threshold will vary from season to season as a function of weather variables and their effect on the reproductive potential of T. indica. Deployment of partial resistance or use of fungicides may be more useful if they push population levels below this threshold. 相似文献
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Establishment of Lolium species resistant to acetolactate synthase‐inhibiting herbicide in and around grain‐importation ports in Japan 
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下载免费PDF全文 Compared with natural seed dispersal, human‐mediated seed dispersal could spread herbicide resistance genes on a much larger scale. Herbicide‐resistant weed seeds have been reported as contaminants in commercial grain. We investigated the contamination of seeds of Lolium species with target‐site mutations conferring resistance to acetolactate synthase (ALS)‐inhibiting herbicides in wheat imported from the USA, Canada and Australia into Japan. We also investigated the establishment of ALS‐inhibiting herbicide‐resistant Lolium species in 12 seaports in Japan that are major entry points for international commodities. We found herbicide‐resistant Lolium spp. seeds from all classes of wheat samples. Resistant individuals became established at six of eight ports where more than 50 kt of imported wheat is unloaded every year. The establishment of resistant Lolium spp. individuals was common at major grain landing ports. Monitoring over 3 years at one port revealed that the frequency of resistant individuals did not fluctuate between years. Many resistant individuals were distributed in front of the entrance of a fodder company, but a few resistant individuals were found in areas 2 km away from the port. The results indicate that gene flow is rare through pollen or seed movement from resistant plants to peripheral populations. Further extensive and long‐term monitoring is necessary to perform a comprehensive risk assessment of herbicide‐resistant plants entering Japan through major commercial ports. 相似文献
5.
Phytosanitary legislation is widely thought to be the most effective means of limiting the entry of alien pathogens without hindering trade. However, there is increasing evidence of limitations and weaknesses in phytosanitary systems worldwide. One such case is the entry and establishment of Colletotrichum acutatum in the UK in the 1980s. To investigate this further, data sets of disease incidence gathered by the authorities responsible for plant health between 1984 and 2008 were analysed to determine how and why the pathogen entered the UK and became established on strawberries. Results suggest that the disease entered the UK in 1982 on plants originating from the USA, a year earlier than the first UK record of the disease was reported. At least 54 further cases of infested plant material breached phytosanitary procedures and entered the UK, 75% of which originated from EU countries. Moreover, internal trade transmission was found to be highly influential in the successful spread of the disease. The effectiveness of phytosanitary procedures is limited when the sector is importing large numbers of plants from nurseries that have a track record of selling infested plant material, even if they are accompanied by a plant passport. By taking greater responsibility in limiting the spread of quarantine diseases, nurseries throughout the EU have an important role to play in limiting the entry of alien pathogens. 相似文献
6.
A. Inman H. A. Magnus L. Riccioni K. Hughes M. Coates A. Barnes V. Barton C. Sansford M. Valvassori G. Di Giambattista A. Porta-Puglia J. Razzaghian G. Peterson 《Plant pathology》2008,57(2):290-300
As part of developing a European Pest Risk Analysis (PRA) for Tilletia indica , the causal agent of Karnal bunt of wheat, teliospore survival studies were done outside under quarantine containment at three European sites (Norway, UK, Italy). At each site, experiments were set up in three consecutive years (Experiments 1, 2 & 3) to determine teliospore survival over time (1–3 years) at 5, 10 and 20 cm depths. Experiments were sampled annually and survival assessed in relation to teliospore recovery and to germination at recovery (T0) and 3 months after recovery in case of burial-induced dormancy ( T3 ). Teliospores survived at all three sites at all depths over all the time periods studied. At each site, there was no evidence of a marked decline in teliospore recovery between sampling years, except in one set of years in one Norwegian experiment. There was no consistent effect of depth on recovery. In general there was little evidence for a marked decline in teliospore germination between sampling years. There was some evidence of a decrease in germination with increasing depth in the UK, and for some time-depth interactions. After 3 years' incubation (Experiment 1), mean teliospore recovery and mean germination were: UK: 61% recovery and 31% ( 33% ) germination for T0 (and T3 ); Italy: 30% recovery and 36% ( 29% ) germination; and Norway: 12% recovery and 19% ( 49% ) germination. Germination for laboratory controls ranged from 20–59% (UK), 18–41% (Italy) and 28–59% (Norway). There was no evidence for burial-induced dormancy except in Norway. Teliospores of T. indica can survive for at least three years in European soils. This prolonged period of survival could support establishment of the pathogen if it were introduced into areas of European cereal production. 相似文献
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Studies on the epidemiology and yield losses from rice black-streaked dwarf disease in a recent epidemic in Zhejiang province, China 总被引：2，自引：0，他引：2
The spread of rice black-streaked dwarf disease, which has emerged as a major problem on winter wheat and the two summer rice crops (early indica and late japonica ) grown in central and southern Zhejiang province, China, is documented from 1995 to 2007. The late japonica crop suffered the most: up to 64 640 ha were affected with estimated losses of c . 120 000 t grain per year. Peak adult numbers of the small brown planthopper vector, Laodelphax striatellus , coincided with the seedling stages of both rice crops and the proportion of the insect population carrying virus increased during 1998–2005. Seedlings with three to four leaves were the most susceptible, whereas plants inoculated after the end of tillering developed few or no symptoms. Disease levels were strongly correlated with numbers of viruliferous vectors. In sowing-date experiments with both rice crops, the earliest sowings had the most disease and suffered the greatest yield losses. With the last sowing date (25 days after the first), there were almost no losses. There were yield losses of 0·80% for every 1% increase in disease incidence in early indica rice and rather more (0·92%) in the late japonica crop. There were large differences in susceptibility between cultivars, indicating the possibility, within currently available germplasm, of using more resistant cultivars to help contain the disease. Changes in cropping practice and in recent winter weather conditions have probably contributed to the emergence of the virus as a major pathogen in eastern China. 相似文献
8.
植物检疫术语是进行植物检疫工作交流的前提与基础,对植物检疫工作具有重要意义。本文通过梳理及规范有害生物相关术语及其定义,明确了有害生物与外来物种的相互关系;通过对有害生物风险分析相关术语及其定义进行整理和规范,提出判定植物检疫性有害生物的评估方法,评估过程可结合适生性分析、传播途径、寄主情况及潜在的经济/环境影响等因素,从进入、定殖、扩散可能性及后果评估等方面进行分析。检疫性有害生物与外来入侵物种有一定交集,因此检疫性有害生物的防控对生物入侵防控具有积极作用。而对有害生物和有害生物风险分析相关术语进行规范也为植物检疫性有害生物名单的制修订提供了科学思路。本文提出的定义修改建议及植物检疫性有害生物评估方法较为概括,仅为定义和名单的制修订工作提供参考。 相似文献
9.
Seasonality plays an important role in the dynamics of infectious disease. For vector‐borne pathogens, the effects of seasonality may be manifested in the variability in vector abundance, vector infectiousness, and host‐infection dynamics over the year. The relative importance of multiple sources of seasonality on the spread of a plant pathogen, Xylella fastidiosa, into vineyards was explored. Observed seasonal population densities of the primary leafhopper vector, Graphocephala atropunctata, from 8 years of surveys in northern California were incorporated into a model of primary spread to estimate the risk of pathogen infection under different scenarios regarding seasonality in vector natural infectivity (i.e. constant or increasing over the season) and grapevine recovery from infection (i.e. none or seasonal recovery). The extent to which local climatic conditions affect risk estimates via differences in vector abundance was investigated. Seasonal natural infectivity, seasonal recovery, and especially the combination, reduced (up to 8‐fold on average) within‐season and cumulative yearly estimates of pathogen spread. Estimated risk of infection also differed greatly among years due to large differences in vector abundance, with wet and moderate winter and spring conditions favouring higher G. atropunctata abundance. Seasonal variation of the pathogen–vector interaction may play an important role in the dynamics of disease in vineyards, reducing the potential prevalence from what it could be in their absence. Moreover, climate, by affecting sharpshooter leafhopper abundance or activity, may influence Pierce’s disease dynamics. 相似文献
10.
Frederick RD Snyder KE Tooley PW Berthier-Schaad Y Peterson GL Bonde MR Schaad NW Knorr DA 《Phytopathology》2000,90(9):951-960
ABSTRACT Karnal bunt of wheat, caused by Tilletia indica, was found in regions of the southwestern United States in 1996. Yield losses due to Karnal bunt are slight, and the greatest threat of Karnal bunt to the U.S. wheat industry is the loss of its export market. Many countries either prohibit or restrict wheat imports from countries with Karnal bunt. In 1997, teliospores morphologically resembling T. indica were isolated from bunted ryegrass seeds and wheat seed washes. Previously developed PCR assays failed to differentiate T. indica from the recently discovered ryegrass pathogen, T. walkeri. The nucleotide sequence of a 2.3 kb region of mitochondrial DNA, previously amplified by PCR only from T. indica, was determined for three isolates of T. indica and three isolates of T. walkeri. There was greater than 99% identity within either the T. indica group or the T. walkeri group of isolates, whereas there was =3% divergence between isolates of these two Tilletia species. Five sets of PCR primers were made specific to T. indica, and three sets were designed specifically for T. walkeri based upon nucleotide differences within the mitochondrial DNA region. In addition, a 212 bp amplicon was developed as a target sequence in a fluorogenic 5' nuclease PCR assay using the TaqMan system for the detection and discrimination of T. indica and T. walkeri. 相似文献
11.
David R. Jones 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):93-104
Tilletia indica, which causes Karnal bunt of wheat, has been perceived as a pathogen that has a high risk of establishment in the UK and
other countries in Europe. This viewpoint is challenged with arguments for the risk of establishment being much lower. The
present distribution of the pathogen and its likely widespread dissemination with consignments of germplasm and wheat seed
from Mexico over a 20 year period without establishment outside the hot arid and semi-arid zones strongly suggests that T. indica is unsuited to environments other than those similar to where it is now found. A critical density of teliospores needs to
remain viable and ungerminated between periods of wheat anthesis and then germinate during a narrow window of opportunity
to ensure infection and establishment. Despite the results of outdoor teliospore longevity experiments, it is by no means
certain that this can occur under European conditions. Generally cooler conditions and more frequent periods of rain in Europe
are likely to trigger teliospore germination at times unsuitable for infection making establishment much more unlikely. A
model based on year-round soil conditions, especially moisture content, is seen as appropriate to predict teliospore survival
and germination potential. It is only after areas where teliospores can survive and germinate in sufficient numbers to guarantee
regular infection cycles have been defined can another model, based on temperature, rainfall and/or humidity prior to anthesis,
be applied to determine if environmental conditions are suitable for infection.
David Jones is a retired employee of the Central Science Laboratory (CSL). Statements and opinions expressed in this paper
are those of the author and are not the views of the Central Science Laboratory. 相似文献
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13.
Dr. E. Meinlschmidt 《Gesunde Pflanzen》2004,56(3):86-92
Over the past few years, there have been repeated reports from the Crop Protection Service in the German state of Saxony of the local appearance of alien weed species, especially in eastern Saxony. Neophytes such as velvetleaf (Abutilon theophrasti), thorn apple (Datura stramonium), Canadian fleabane (Conyza canadenzis), and apple of fern (Nicandra physalodes) have been particularly conspicuous. During recent years in agricultural areas in warmer parts of Europe, some of these weeds have developed into problematic species. Triennial field investigations into the control of velvetleaf in sugar beet have shown that herbicides registered in Germany for the control of weed species are not sufficiently effective every year. Velvetleaf proved to be extremely resistant to the herbicide treatments already tested, and only in one trial year was it possible to control it effectively using triflusulfuron. Owing to inadequate control in sugar beet, the spread of Abutilon theophrasti in agricultural fields can not be ruled out in the future. The possible reasons for it being categorised as invasive are discussed in the following article. Monitoring of possible introduction pathways and appearance of potentially invasive alien species and suitable control measures might at least hinder their introduction, establishment, and spread in agricultural areas. 相似文献
14.
M. W. SHAW 《Plant pathology》1994,43(5):790-801
Two models of plant disease in crops regulated by a virus disease or by a hyperparasite are introduced. If the host crop is annually harvested or dies back, the pathogen population at the end of each year may fluctuate indefinitely and irregularly in a way which depends very precisely and for ever on the initial populations. This means that even in an environment which is identical every year, the pathogen populations in each year vary enormously and erratically. However, the combinations of pathogen and virus incidence or hyperparasite infection that can occur exhibit very well defined patterns, even if parameters in the model exhibit substantial random annual variation. It is important that pathologists should be aware that population fluctuations may not be caused by environmental fluctuations and may be, in principle, unpredictable by a deterministic model. 相似文献
15.
H. A. Narouei-Khandan S. P. Worner S. L. H. Viljanen A. H. C. van Bruggen E. E. Jones 《Plant pathology》2020,69(1):17-27
Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established. 相似文献
16.
S. Brunel D. Panetta G. Fried D. Kriticos R. Prasad A. O. Lansink A. Shabbir T. Yaacoby 《EPPO Bulletin》2014,44(3):479-489
Parthenium or famine weed (Parthenium hysterophorus L.) is an annual plant originating from the Americas, which is a major invasive alien plant in almost all continents. While the deleterious impacts of the species on agriculture, human and animal health have been well documented, information on the pathways of entry of the species is only occasionally mentioned in the literature. As this invasive alien plant is only recorded as established in Israel and Egypt within the Euro‐Mediterranean region, the European and Mediterranean Plant Protection Organization identified P. hysterophorus as an emerging threat. EPPO therefore performed a Pest Risk Analysis on this species to assess the risk it represents and to consider appropriate management options. The EPPO Pest Risk Analysis main outputs are summarized in this article, indicating the probability of entry of the species via the different pathways within the EPPO region, its probabilities of establishment and spread, and the magnitude of its potential agricultural, environmental and social impacts. 相似文献
17.
A. J. WRIGHT 《EPPO Bulletin》1998,28(4):513-518
Since the outbreaks of potato brown rot (caused by Ralstonia solanacearum) in EU Member States in the mid 1990s, EU measures against this pest have been strengthened. Factors in the spread of R. solanacearum are reviewed: planting material, Solanaceous weeds, water, soil, waste, machinery and equipment. The Control Directive of 1998 aims to prevent spread and ensure eradication. It provides for the establishment of a demarcated zone whenever the pest is found, for measures to prevent spread from this zone and for measures to eliminate the pest within the zone. 相似文献
18.
Steven M. White Juan A. Navas-Cortés James M. Bullock Donato Boscia Daniel S. Chapman 《Plant pathology》2020,69(8):1403-1413
Xylella fastidiosa is an important insect-vectored bacterial plant pathogen with a wide host range, causing significant economic impact in the agricultural and horticultural industries. Once restricted to the Americas, severe European outbreaks have been discovered recently in Italy, Spain, France, and Portugal. The Italian outbreak, detected in Puglia in 2013, has spread over 100 km, killing millions of olive trees, and is still expanding. To date, quantified assessment of important epidemiological parameters useful for risk assessment and management, such as transmission rates, symptomless periods, and time to death in field populations, has been lacking. This is due to the emergent and novel nature of the outbreak and length of time needed to monitor the course of disease progression. To address this, we developed a Bayesian method to infer epidemiological parameters by fitting and comparing compartmental epidemiological models to short snapshots of disease progression observed in multiple field plots. We estimated that each infected tree with symptoms is able to infect around 19 trees per year (95% credible range 14–26). The symptomless stage was estimated to have low to negligible infectivity and to last an average of approximately 1.2 years (95% credible range 1.0–1.3 years). Tree desiccation was estimated to occur approximately 4.3 years (95% credible range 4.0–4.6 years) after symptom appearance. However, we were unable to estimate the infectiousness of desiccated trees from the data. Our method could be used to make early estimates of epidemiological parameters in other emerging disease outbreaks where symptom expression is slow. 相似文献
19.
In 2004, Scaphoideus titanus , vector of Grapevine flavescence dorée phytoplasma, was first recorded in Austrian vineyards. The absence of the phytoplasma in 2004-06 was confirmed by molecular analyses of grapevine and vector samples. To estimate the risk to Austrian viticulture a Pest Risk Analysis (PRA) was conducted, following the EPPO decision support scheme. The highest risk of introduction arises from the extensive trade in rootstocks and, especially for vineyards located along traffic routes and waterways, from the passive or active spread of the vector. Climate will not limit the establishment of the vector in the large northern Austrian vine-growing regions of Niederösterreich and Burgenland. At present the probability that the disease and vector become associated is restricted to parts of South Styria. Plant protection practice cannot prevent the establishment and spread of vector populations, especially in sustainable production systems, which forms more than 70% of the total Austrian viticulture area. The possibility for containment or even eradication is given, but requires an early recognition of the vector and disease and the immediate initiation of measures. Otherwise, losses to vine growers, follow-up costs for eradication and additional efforts in the production of plants would be substantial. Following the assessment, legal measures and recommendations to prevent disease entry and to minimise impacts of established vector populations are considered. 相似文献
20.
Australian wheat consigned for export from Australian ports was surveyed in March 2004 using a national diagnostic protocol for detection and identification of Tilletia indica . No ustilospores of T. indica were detected, confirming previous surveys which have failed to detect T. indica in Australia. However, the survey detected moderate levels of the common smuts Tilletia caries (syn. Tilletia tritici ), Tilletia laevis and Urocystis agropyri , and very low levels (average fewer than six ustilospores per 150 g sample) of an unidentified dark, tuberculate-spored Tilletia in ≈ 60% of samples tested. Comparison with herbarium specimens enabled identification of the majority of the tuberculate ustilospores as Tilletia ehrhartae , a smut fungus known to infect only Ehrharta calycina (perennial veldt grass) and which is common in southern Australia. A smaller number of tuberculate smut ustilospores were identified as Tilletia walkeri , a smut of Lolium spp. recorded in Australia but apparently uncommon. Both T. ehrhartae and T. walkeri bear sufficient resemblance to T. indica for misidentifications to be possible where only a very few ustilospores are seen, although T. ehrhartae ustilospores are always <25 µ m in diameter. The frequent presence of ustilospores of both T. ehrhartae and T. walkeri as contaminants of Australian wheat grain exports has significance for diagnosticians testing Australian export wheat, as it demonstrates the potential for tuberculate ustilospores of species other than those covered in existing diagnostic protocols to be misidentified as T. indica . This paper describes T. ehrhartae in detail, and provides criteria for its differentiation from T. indica , T. walkeri and some other species. 相似文献