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1.
Samenvatting Op vele bedrijven, waar een sterke rotatie van granen in het bouwplan is opgenomen, kan het havercystenaaltjes veelvuldig moeheidsverschijnselen in haver veroorzaken. Ook op bedrijven, waar dit gewas geen afwijkingen in de groei vertoont, komt het aaltje, zij het in geringe concentraties, algemeen voor. Tussen de besmettingsgraad van de grond en de schade aan het gewas bestaat een zeker verband. Dit verbank kan sterk beïnvloed worden door verschillende bijkomende factoren, waaronder de watervoorziening van der planten een belangrijke rol speelt.Het is nog niet duidelijk in hoeverre de techniek van het grondmonsteronderzoek gewijzigd dient te worden om te voorkomen, dat de levende inhoud van de cysten terugloopt.Summary The cereal root eelworm has become a serious pest in oats in some parts of the Netherlands, especially on light, sandy soils.In March and April 1955 1400 soil samples were collected from farms where the occurrence of the nematode was to be expected.In two different areas the degree of infestation was 78 and 96% of the total of fields under investigation. These figures indicate that the concerning farms were generally infested, but they do not represent the mean situation of the area.During the growing season each oat crop was examined for symptoms of the disease. The data collected were compared afterwards with the degree of infestation. There proved to be a positive correlation between the degree of infestation of the soil and the damage to the crop (tables 1 en 2). Several circumstances influence this correlation, among which the water supply of the plants seems to be a very important one.Cyst populations were identified by morphological characters to separate them from the clover root eelworm,Heterodera trifolii (Goffart, 1936), which was also present in 6,5% of the samples in one, and in 32% of the samples in the other area.The larvae in the cysts ofH. avenae evidently do not stand dry preservation, which is in accordance with recent experience in England (2).Dry preservation inplastic cavity slides for 1–3 weeks resulted in a decrease of viable cysts and larvae of 52%. A more suitable technique for collecting and handlingH. avenae in studied for further work.Het onderzoek werd verricht in samenwerking met de Rijkslandbouwconsulenten te Zutfen en Horst (L.) en het kantoor van de Plantenziektekundige Dienst te Doetinchem.  相似文献   

2.
Summary In the course of a survey of the occurrence of cereal root eelworm made in the province of Limburg in 1955, some observations were made on the population density of the nematodes before and after various crops, for although it was well known that non-host crops decreased the population, little information was available on the effect of different cereals and graminaceous crops on the eelworm numbers.In 54 fields of farms at IJsselstein (Limburg) the pre- and postcropping nematode population was estimated by examining samples of 200 ml of soil in March and November 1955. Each sample consisted of 60 rods well distributed over the field. The results are summarized in table 1. Oats is an efficient host plant, but rye, some grasses and leys decrease the eelworm population and these may therefore be considered to be suitable crops to precede oats on infested land. Some rotations are suggested which may be suitable for infested fields, and which may help to avoid damage to oats in Limburg province.  相似文献   

3.
During the last decade, new control possibilities for the potato root eelworm have come to the fore, namely resistant potato varieties and soil disinfection. These have led to an integrated approach to the control of the potato root eelworm in the Netherlands. For this purpose, a number of potato rotations, aiming at the prevention or elimination of non-detectable populations of the potato root eelworm, are prescribed for non-infested fields. These regulations allow the farmer to grow potatoes more frequently on non-infested soils if he uses control measures (i.e. resistant potato varieties, soil disinfection). More stringent restrictions are in force for infested fields on which the growing of susceptible crops and propagation material is, of course, prohibited.  相似文献   

4.
J. C. FORBES 《Weed Research》1984,24(6):431-438
A roadside survey of 4749 fields in eight areas of NE Scotland was conducted annually from 1979 to 1982. The proportion of grass fields infested with ragwort remained steady at 18–19% from 1979 to 1981 but fell to 13·5% in 1982. This fall resulted from fewer fields becoming newly infested and from more fields that had remained in grass ceasing to be infested. The proportion of infested fields remaining in grass that showed a reduction of two or more points on a 0–5 logarithmic scale of ragwort density (a possible indication of the frequency of control measures) was 24·0% in 1979–1980, 21·7% in 1980–1981 and 36·3% in 1981–1982. The incidence of ragwort infestation was consistently higher in some areas than in others and was not related to the proportion of arable crops. The change in incidence of infestation varied greatly between different areas, as did the proportion of infested fields whose score on the 0–5 scale fell by two or more points. In 1979–1980 and 1980–1981 this proportion had to exceed 22% to effect a net decrease in the incidence of infestation in an area, but in 1981–1982 no relationship was evident between these two measures of change. The incidence of infestation in all areas increased with increasing sward age but one area (Moray and Nairn) had a much higher proportion of young grass infested than any of the others. Over 99% of ragwort infestations consisted of Senecio jacobaea, infestations of S. aquatints Huds. being rare.  相似文献   

5.
By the end of summer 2005, four sites of infestation by Anoplophora glabripennis (Coleoptera, Cerambycidae) had been detected in three European countries: Austria in 2001, at Braunau am Inn; France in 2003, at Gien, and in 2004, at Sainte‐Anne‐sur‐Brivet; and Germany in 2004, at Neukirchen am Inn. Two sites of infestation by Anoplophora chinensis have been detected in two European countries: Italy in 2000, at Parabiago, and France in 2003, at Soyons. The history of the A. glabripennis and A. chinensis discoveries is presented, as well as the respective management responses (monitoring and destruction of the infested trees). By the end of summer 2005, the eradication was not yet fully achieved in any of the four A. glabripennis‐infested sites. In contrast, no new A. chinensis‐infested trees had been found at Soyons, France, since 2003. At Parabiago, Italy, monitoring is taking place: the A. chinensis infestation affects 16 municipalities over more than 60 km2. By summer 2005, destruction on a large scale of the infested trees had not yet taken place, but tree‐cutting of more than 1000 trees had been planned for winter 2005‐06. Given the current substantial extent of the A. chinensis infestation near Milan, and the density of the established A. chinensis populations, there is a high probability that the status of the pest in Italy will soon be raised from ‘introduced’ to ‘invasive’.  相似文献   

6.
Spread of Phytophthora root and crown rot in three pot plant species was studied on ebb-and-flow benches where the nutrient solution was recirculated. The plant species and their respective pathogens were: Saintpaulia ionantha – P. nicotianae, Gerbera jamesonii – P. cryptogea, and Spathiphyllum wallissii – Phytophthora spp. Ebb-and-flow benches were infested with the pathogen using different methods: 18–25% of the plants on a bench were inoculated or potted in soil infested with the pathogen or the nutrient solution was infested by either zoospores or mycelium fragments. More than 80% of the inoculated Saintpaulia plants and 22% of plants potted in infested soil developed disease but no spread of the disease was observed. Infestation of the nutrient solution did not result in any diseased Saintpaulia plant. More than 70% of the Gerbera plants developed disease as a result of spread of the pathogen irrespective of the infestation method used. No significant spread of the disease was observed with inoculated Spathiphyllum plants nor from plants potted in infested soil. A few Spathiphyllum plants developed disease symptoms after infestation of the nutrient solution with zoospores. In one experiment, nearly all Spathiphyllum plants were diseased after infestation of the nutrient solution with mycelium fragments. The presence of an irrigation mat significantly reduced the spread of the Phytophthora disease in Gerbera and Spathiphyllum. The possibility of an irrigation mat acting as a filter for zoospores is discussed.  相似文献   

7.
Surveys of sugar beet crops for beet cyst nematode ( Heterodera schachtii Schmidt) in seven selected areas of England have provided data on distribution of the pest and on some factors affecting its occurrence. These data were mapped by CAMGRID computer program.
Infestations occurred mostly on the East Anglian fenland (14% of fields infested) and in this area were more frequent nearer the sugar beet processing factory. In the remaining areas the few infested fields (5% or less) were generally scattered but a small concentration of infestation occurred in the West Midlands in an area of intensive horticulture with frequent brassica crops. The survey data did not support the view that beet cyst nematode infestations occur more frequently near access points to the crop. In the surveyed areas frequency of host crops appears to be more important than soil type in determining the likelihood of infestation.  相似文献   

8.
Using quantitative PCR, DNA of Plasmodiophora brassicae, the causal agent of clubroot, was detected and quantified on canola, pea and wheat seeds, as well as on potato tubers, all harvested from clubroot‐infested fields in Alberta, Canada. Quantifiable levels of infestation were found on seven of the 46 samples analysed, and ranged from <1·0 × 103 to 3·4 × 104 resting spores per 10 g seeds; the vast majority (80–100%) of resting spores on these samples were viable, as determined by Evan’s blue vital staining. However, the levels of infestation found were generally lower than that required to cause consistent clubroot symptoms in greenhouse plant bioassays. While the occurrence of P. brassicae resting spores on seeds and tubers harvested from clubroot‐infested fields suggests that seedborne dissemination of this pathogen is possible, practices such as commercial seed cleaning may be sufficient to effectively mitigate this risk.  相似文献   

9.
The infestations of two biotypes of Panicum miliaceum L. were monitored over a 5-year period (1981–1985) as they occurred in two townships in southwestern Ontario, Canada. On average, 16·5% of the cultivated fields in Hullett township were infested with the black-seeded biotype while 12·9% of the fields in North Norwich township were infested with the golden-seeded biotype. Neither population showed clear signs of increasing. The two biotypes were similar in their ability to persist as adult infestations. The black-seeded biotype showed a greater potential for colonizing uninfested fields. The crops grown in this region showed different susceptibilities to infestation by P. miliaceum. Corn (maize) fields were susceptible while most grain fields were resistant to infestation. White beans were susceptible to infestation by the black-seeded biotype. Wheat and oat crops were more resistant to infestation by the golden-seeded biotype than to those of the black-seeded biotype.  相似文献   

10.
The present study was performed to investigate whether Plasmodiophora brassicae can be disseminated by livestock manure. A quantitative PCR (qPCR) assay was developed and used to detect and quantify P. brassicae in manure samples from naturally and artificially infested chickens and pigs. In naturally infested manure, quantifiable levels of infestation were observed in 7 out of the 28 samples, ranging from 103 to 107 resting spores per g of manure. The vast majority of the resting spores (76–91%) were viable, as determined by a dual fluorescence viability assay. Clubroot symptoms developed on plants inoculated with P. brassicae resting spores isolated from all seven qPCR‐positive samples. Artificially infested manure samples were produced by feeding chickens and pigs on P. brassicae‐contaminated feed. The levels of infestation were 103 resting spores per g of manure for both chicken and pig manure sampled 24 and 48 h after feeding, respectively. Spore viability was >80% for both samples, and the disease severity indices were both >40 as indicated by bioassay. This showed that resting spores can survive the digestive tracts of chickens and pigs, and retain strong pathogenicity. The findings indicate that manure dissemination is possible for P. brassicae. Farmers should avoid feeding livestock on P. brassicae‐contaminated feed or applying infested manure as fertilizer on land intended for crucifer crops.  相似文献   

11.
According to the new trend of insect pests control in fruit orchards, biological in addition to mechanical control were evaluated for their efficiency on the reduction ofP. paradoxa population on fig trees during 1996, 1997 and 1998. Primary trials using the bacterial biopreparations of Delfin, Dipel and Bactospeine at the concentration of 200g/100 l. w. resulted in 81.8, 75.8 and 72.3% reduction of pest infestation, respectively. Pruning the infested branches, worming the larvae inside their tunnels and both mechanical treatments together along two successive years, reduced the infestation by 17.5, 47.4 and 57.9%, respectively. A control programme ofP. paradoxa was conducted using the techniques of pruning and worming besides spraying with bacterial insecticides at a rate of 200g/100 l.w. The performed mechanical and biological treatments together for one year gave 79.2–94.5% reduction of infestation, that reduction increased to 83.0–98.1% when these treatments were applied two years successively.  相似文献   

12.
According to the new trend of insect pests control in fruit orchards, biological in addition to mechanical control were evaluated for their efficiency on the reduction ofP. paradoxa population on fig trees during 1996, 1997 and 1998. Primary trials using the bacterial biopreparations of Delfin, Dipel and Bactospeine at the concentration of 200g/100 l. w. resulted in 81.8, 75.8 and 72.3% reduction of pest infestation, respectively. Pruning the infested branches, worming the larvae inside their tunnels and both mechanical treatments together along two successive years, reduced the infestation by 17.5, 47.4 and 57.9%, respectively. A control programme ofP. paradoxa was conducted using the techniques of pruning and worming besides spraying with bacterial insecticides at a rate of 200g/100 l.w. The performed mechanical and biological treatments together for one year gave 79.2–94.5% reduction of infestation, that reduction increased to 83.0–98.1% when these treatments were applied two years successively.  相似文献   

13.
The red palm weevil Rhynchophorus ferrugineus (Olivier) is the most serious pest of palms in Turkey. Weevil infestation was first detected in Turkey in summer 2005 in parks and gardens of Mersin province, along the Mediterreanean coast of Turkey. Following the discovery of the pest, destruction of infested plant material, prophylactic insecticide chemical treatments, as well as adult weevil trapping were carried out on palm plantations. Traps containing a commercial aggregation pheromone were hung on palm trees at a high density, in order to monitor the pest infestation and reduce the weevil population by mass trapping. A significant decrease in the number of trapped beetles and destruction of infested plant material was observed in 2009 and continued in the following years in several cities in Turkey. Therefore, it has been observed that mass trapping and curative pesticide applications have played a significant role in the suppression of R. ferrugineus populations in palm plantations.  相似文献   

14.
A study was carried out to determine the impact of Leptocybe invasa infestation on growth and biomass production of Eucalyptus grandis W. Hill ex Maiden and E. saligna Smith seedlings in Tanzania. Three- month old seedlings were infested with L. invasa. Twenty two weeks post infestation, heights of infested E. grandis seedlings were reduced by 39.6%, while diameters were reduced by 11.3% compared to uninfested seedlings. On the other hand, the heights of infested E. saligna seedlings were reduced by 38.2% and diameters were reduced 7.7% compared to uninfested seedlings. Dry weight biomass reduction of infested seedlings was significantly higher on stem and leaves than roots and branches of both E. grandis and E. saligna. The impact of L. invasa infestation on growth and biomass production was higher in E. grandis than E. saligna. Prevention and control of L. invasa infestation should be given priority. Similar future trials should examine other commercially grown Eucalyptus species in Tanzania.  相似文献   

15.
Golden potato cyst nematode, Globodera rostochiensis , has been known to occur in Hungarian potato fields for more than 20 years. The Hungarian NPPO has been carrying out a country-wide Globodera monitoring programme since 1995 and has inspected 16 000 samples. Until 2000, all records were of G. rostochiensis . However, in 2001, three localities in Pest county were found to be infested with Globodera pallida . This was the first official record of G. pallida in Hungary. The two species have been found together in five fields. Unmixed populations of G. pallida have not been found. Identification was based on morphometric data, as well as on biochemical methods (ELISA technique).  相似文献   

16.
Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4–6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given. © 2001 Society of Chemical Industry  相似文献   

17.
Rainfed lowland rice fields in northern Togo are increasingly infested by the facultative hemiparasitic weed Rhamphicarpa fistulosa that is widely reported throughout sub-Saharan Africa to be one of the most damaging weeds in rice fields. In this geographical area, some studies have shown that soil characteristics may influence the presence and/or the level of infestation of some parasitic weeds, but none have been conducted on R. fistulosa. Based on surveys conducted in northern Togo over two years in 66 lowland rice fields, we characterised the level of infestation of R. fistulosa as well as physico-chemical characteristics of soils. We highlighted that fields with medium-to-high levels of infestation of R. fistulosa (more than 5 plants per m2) were mainly characterised by a coarser soil texture, a higher potassium content and a higher pH, while fields without R. fistulosa were characterised by a lower proportion of silt content. In contrast, the level of infestation of R. fistulosa appeared only marginally influenced by soil organic carbon and nitrogen in our study. Considering these results, options to modify the main physico-chemical characteristics of soils that influence the level of infestation of R. fistulosa are likely difficult to implement. In order to continue rice production in these lowland fields, we suggest several measures to better manage R. fistulosa seedbank and development.  相似文献   

18.
The sensitivity of a bioassay in detecting soil inoculum of Colletotrichum coccodes and Helminthosporium solani was examined using potato minitubers and microplants. Tests were conducted on soils which were collected from fields in which the interval after a previous potato crop differed, and which were also artificially infested with conidia or microsclerotia. For C. coccodes , determining plant infection based on the occurrence of infected roots after 9–12 weeks was a sensitive method for detecting and quantifying the amount of inoculum in soil. Infestations of less than 0·4 microsclerotia per g soil were detected in artificially infested soils. A semiselective medium, developed for isolating C. gloeosporioides from pepper, detected soil infestations by C. coccodes as low as nine conidia or one microsclerotium per g soil in artificially infested soil. For H. solani , infection on minitubers was a sensitive measure, with soil inoculum of fewer than 10 conidia per g soil being detected. Soil infestation could be quantified by assessing the percentage surface area of minitubers covered by sporulating lesions, which was strongly related to the amount of soil infestation. The results of these bioassay tests were compared with published results for real-time quantitative PCR assays on the same soils. The two methods were in good agreement in artificially infested soils, but the bioassay appeared to be more sensitive with naturally infested soils.  相似文献   

19.
Summary Raspberries and strawbereis planted several years after a previous crop of raspberries were found attacked byPratylenchus penetrans. Raspberries planted in places where appled trees had been taken out showed slightly stunted growth and a moderate attack of the roots byP. penetrans.The symptoms of heavily infested raspberries were: severely stunted growth of above ground parts without other particular symptoms; a very poor root system, parts of which are completely dead and blackened or show dead, blackened bark, and the absence of fine feeding roots. In cases of light attack the root system is more normal but there is a number of rather large black lesions.Raspberries should not be planted after raspberries, after fruit trees susceptible to attack byP. penetrans, after strawberries or on possibly infested soil (in general light soils) unless a determination of the degree of infestation in the plant sites has shown that the place is safe. In case of infestation suitable measures to eradicate the nematodes should be taken. It may be expected that a fairly light degree of infestation of the soil is sufficient to cause appreciable damage.  相似文献   

20.
Present state of Solanum elaeagnifolium Cav. infestation in different crops of the Tadla perimeter (Morocco) The present state of infestation by Solanum elaeagnifolium Cav. in crops of the whole agricultural region of the Tadla (Central Morocco) is presented. Using the ecological profile method, it was found that, on the one hand, the Béni Amir perimeter (north Tadla) is much more heavily infested than the Béni Moussa perimeter (south Tadla) and, on the other, infestation is heaviest in spring crops (cotton, maize, sesame). A map attached to the text shows the exact distribution of the species within this region.  相似文献   

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