共查询到20条相似文献，搜索用时 15 毫秒
1.
北京地区花生病毒病及流行规律研究 总被引：3，自引：1，他引：3
1985—1987年研究表明北京地区花生上流行的病害主要有黄瓜花叶病毒CA株系(CMV-CA)引起的黄花叶病害和花生轻斑驳病毒(PMMV)引起的轻斑驳病害。血清鉴定451份花生病害样品,黄花叶病害样品受CMV-CA侵染占95.7％,轻斑驳病害样品受PMMV侵染占91.3％,中后期病害样品受CMV-CA和PMMV复合感染较普遍。CMV种传率2％左右,种传病苗在花生出苗后开始出现,6月病害进入高峰。三年CMV-CA流行程度明显不同,主要取决于苗期蚜虫发生早晚、发生量及苗期降雨量。PMMV种传率低于1％,病苗出现稍晚,但病害扩散快,6月上旬进入高峰,7月上、中旬发病率达100％。三年流行程度差异不明显。 相似文献
2.
R. B. E. Kimber D. Shtienberg M. D. Ramsey E. S. Scott 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(2):141-152
Didymella rabiei, the causal agent of ascochyta blight, survives on infected seeds and seedlings. Diseased seedlings originating from infected
seeds occasionally serve as the source for primary infection in chickpea crops. Experiments carried out independently in Australia
and in Israel provided quantitative information on the temporal and spatial distribution of ascochyta blight from initial
infections and on the relationship between the amount of initial infection and the intensity of subsequent epiphytotics for
cultivars differing in susceptibility to the pathogen. Disease spread over short distances (<10 m) from individual primary
infections, was governed by rain and wind, and was up to five times greater down-wind than up-wind. Cultivar response to D. rabiei significantly affected the distance and area over which disease spread and the intensity of the disease on infected plants.
At onset of the epiphytotic, the relationship between disease spread and time was exponential (P < 0.05; R
2 > 0.95) and the area of the resulting foci was over 10 times greater in susceptible cultivars than in resistant cultivars.
Regression equations showed the relationship between disease severity and the distance from the focus-plants was inverse-linear
for all cultivars tested (P < 0.05). A simulation model based on the experimental data revealed that even if primary infection is infrequent (less than
1% of plants), the consequences are potentially devastating when susceptible cultivars are used. The epidemiological information
and simulation model generated by this study provide an increased understanding of the development of an epiphytotic in which
the primary foci of disease originate from infected chickpea seedlings. 相似文献
3.
ABSTRACT The spread of Fusarium head blight of wheat from a small area inoculum source was examined in wheat plots (100, 625, or 2,500 m(2)) inoculated in the center with Gibberella zeae-colonized corn kernels or macro-conidia sprayed on heads at anthesis. With the first inoculation method, disease foci were produced from ascospores released from perithecia formed on inoculated kernels. With the second inoculation method, disease foci were produced by macroconidia directly applied to the heads. Some plots were misted during anthesis. Plots were divided into grids, and disease incidence on spikelets and seeds was assessed at the grid intersections. Isopath contour maps were constructed using an interpolation procedure based on a weighted least squares method. Disease gradients were constructed from the isopath contours in the direction parallel to average nightly wind vectors using an exponential model. This study was conducted over a 3-year period at two sites: one in Quebec and one in Ontario. Both inoculation methods resulted in a discrete, primary focus of head blight in each plot, with one or two smaller secondary foci in some plots. The highest incidence of disease on spikelets or seed was commonly displaced somewhat from the inoculum source, usually downwind. The gradient slopes of seed and spikelet infection ranged from -0.10 to -0.43 m(1) in plots with ascospore inoculum and from -0.48 to -0.79 m(1) in plots inoculated with macroconidia. Seed infection declined to 10% of the maximum within 5 to 22 m from the focal center in asco-spore-inoculated plots, and within 5 m in a macroconidia-inoculated plot. Gradients were usually steeper upwind compared with downwind of the inoculum source. In misted plots, incidence of disease was higher and more diffuse than in nonirrigated plots. Based on gradients and dispersal patterns, disease foci in plots inoculated with G. zeae-colonized corn kernels probably arose from airborne ascospores rather than from splash-borne macroconidia and were the result of infection events that occurred over a short period of time. Comparison of conidial- and ascospore-derived disease gradients indicated a lack of secondary infection, confirming that Fusarium head blight is primarily a monocyclic disease. 相似文献
4.
N. M. Horn S. V. Reddy D. V. R. Reddy 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(2):221-224
Yield losses caused by chickpea chlorotic dwarf virus in chickpea were estimated by comparing uninfected and infected plants in the field at two locations in India. When infection was before flowering, yield losses of individual plants amounted to nearly 100% in the three cultivars studies. Plants that became infected during flowering had yield losses of 75–90%. Percentage of crop loss is likely to equal percentage of disease incidence, since plant densities in farmers' fields are probably too low to allow uninfected plants around infected ones to compensate the yield losses of infected plants.Submitted as Journal Article No. 1624 by ICRISAT. 相似文献
5.
William W Kirk Brendan A Niemira Jeffrey M Stein Raymond Hammerschmidt 《Pest management science》1999,55(12):1151-1158
Fungicides were applied as seed-piece treatments to control potato late blight, caused by Phytophthora infestans, US8, A2 biotype in controlled environment and field experiments. Efficacy of seed treatments for controlling late blight was examined under three disease development regimes simulated by artifical inoculation; (a) seed-borne infection, (b) transmission of infection resulting from spread during the seed-cutting operation, and (c) infection of foliage by aerial inoculation. Emergence of plants from the seed-borne infection was uniformly low (<40%) in controlled environment and field experiments. In controlled environment experiments some of the plants that emerged from fungicide-treated seed-pieces were infected with late blight. Following exposure of tuber surfaces to P infestans, emergence rates from seed-pieces treated with formulated products that included mancozeb in the formulation were comparable to the untreated and non-inoculated control in controlled environment and field experiments. Plants that emerged from non-inoculated seed-pieces treated with fungicides that contained active ingredients known to be effective against foliar late blight had lower percentage foliar infection after inoculation than the untreated control. Leaves close to the base of the stem had fewer infections than leaves attached at the mid region of the main stem, 14 days after inoculation, in some of the controlled environment studies. In contrast, field experiments conducted under conditions conducive to late blight development showed that none of the seed treatments applied to late blight-free seed-pieces delayed the onset and severity of late blight infection. In potato production areas at risk of early season late blight, seed treatments applied to healthy seed may confer limited protection against late blight between planting and the first scheduled applications of prophylactic foliar fungicides. © 1999 Society of Chemical Industry 相似文献
6.
Chickpea was surveyed for viruses in the main growing areas of the crop in Morocco. A total of 36 fields was examined and 167 samples with symptoms suggestive of virus infection were collected. Serological testing using polyclonal antisera and monoclonal antibodies revealed the presence of the following viruses: alfalfa mosaic alfamovirus (AMV), broad bean mottle bromovirus (BBMV), broad bean stain comovirus (BBSV), bean yellow mosaic potyvirus, cucumber mosaic cucumovirus (CMV), faba bean necrotic yellows nanavirus (FBNYV), lettuce mosaic potyvirus, pea seed-borne mosaic potyvirus (PSbMV), and luteoviruses. Field symptoms of these viruses in chickpea comprised mosaics, yellowing, stunting, narrowing of leaflets and bushy growth. AMV, luteoviruses and potyviruses were found spread over the chickpea-growing regions, while BBSV, BBMV, and FBNYV were confined to some areas. Virus incidence per field varied from 1 to 40% for luteoviruses and from 1 to 20% for mosaic-inducing viruses. AMV, luteoviruses, potyviruses and CMV were detected in 89, 83, 75 and 42%, respectively, of the surveyed fields. BBMV, BBSV and FBNYV were less widespread at the national level. This is the first report of the occurrence of viruses other than CMV and BBMV in chickpea in Morocco, and the first record of the natural occurrence of BBSV and PSbMV in chickpea. 相似文献
7.
ABSTRACT Spatial and temporal dynamics of late blight were investigated from color, infrared aerial photographs of five commercial potato fields in the Columbia Basin during epidemics in 1993, 1995, and 1998. Aerial photographs were taken one to four times at 6- to 21-day intervals. Photographs were scanned and pixels, representing approximately 1 m(2) in the field, were used in the analysis. Late blight-infected plants were aggregated as indicated by runs analysis. Significant z-tests were computed for four directions during each sampling date in each of the five fields. Absolute z-values for runs analysis increased, indicating increasing aggregation in the four directions, as disease incidence increased in the early and midphases of the epidemics in each field. Variograms indicated the existence of autocorrelation among infected plants in four directions; the range of influence increased as disease incidence increased except at the highest levels of disease. Late blight was observed to spread in fields as foci. Late blight foci enlarged in size, produced distinct daughter foci, and coalesced. A field where initial inoculum likely originated from infected seed tubers exhibited less initial aggregation than the other fields, perhaps due to a different source of primary inoculum. Aerial photography coupled with spatial analyses of late blight-infected plants was an effective technique to quantitatively assess disease patterns in relatively large fields and was useful in quantifying an intensification of aggregation during the epidemic process on a large scale. 相似文献
8.
Colonization of red raspberry flowers and fruit by Botrytis cinerea was determined during 2017–2018 growing seasons under commercial fungicide application programmes used for grey mould management in northwestern Washington, USA. Colonization of flowers and fruit was assessed qualitatively (incidence, %) and quantitatively (abundance, number of colonies) by recovering B. cinerea from surface-disinfested samples. Both incidence and abundance of flower colonization were significantly lower than fruit colonization in both untreated and fungicide-treated plots. Incidence of flower colonization did not differ significantly between untreated and fungicide-treated plots (43% vs. 45%, respectively). In contrast, significantly greater colonization incidence was detected at green fruit stage in untreated compared to fungicide-treated plots (96% vs. 77%, respectively). Ripe fruit had the greatest colonization incidence among the three stages sampled and colonization was not significantly different between untreated and fungicide-treated plots (100% vs. 92%, respectively). Similarly, colonization abundance of flowers did not differ significantly between untreated and fungicide-treated plots (1.0 colonies per colonized flower in both treatments), but colonization abundance of green and ripe fruit was decreased 2.3- and 2.1-fold, respectively, in fungicide-treated plots. DNA fingerprinting analysis of the pathogen revealed that different multilocus genotypes colonized flowers and fruit within the same inflorescence and that genotypic diversity increased through time, suggesting independent infection events. Overall, our results demonstrate that under current environmental conditions, raspberry flowers may not be the exclusive or major route of infection for grey mould of red raspberry in northwestern Washington. Implications of current findings for management and further research are discussed. 相似文献
9.
Roger A.C. Jones 《Integrated Pest Management Reviews》2001,6(1):15-46
There is a need to develop integrated disease management strategies that are comprehensive and can protect farmers from the economic hardship that arises when epidemics of non-persistently aphid-borne viruses damage their crops. The aim of this review is to provide a model for future programmes to use when developing such strategies for different combinations of non-persistently aphid-borne viruses and crops. The model programme described is a 15-year study to develop integrated management strategies against two non-persistently aphid-borne viruses causing damaging diseases of lupins and to get them adopted by farmers. The success of the programme depended on an interdisciplinary team approach, obtaining a detailed understanding of the factors favouring virus epidemics, field evaluation for virus resistance, and field experiments that determined the effectiveness of individual control measures. The strategies developed were designed to cause few additional labour demands, and minimal disruption to normal farming operations or extra expense.The programme devised integrated management strategies for the diseases caused by Cucumber mosaic virus (CMV) and Bean yellow mosaic virus (BYMV) in crops of narrow-leafed lupin (Lupinus angustifolius) under the conditions of low-input, dryland agriculture in the south-west Australian grainbelt, which has a Mediterranean-type climate. CMV is introduced into lupin crops by sowing virus-infected lupin seed while aphids spread BYMV into the growing crop from adjacent virus-infected, clover-based pastures. Grain yield losses are substantial when virus spread by aphids is sufficient to cause high incidences of infection within crops. The management strategies were gradually improved and expanded as understanding of the epidemiology of viruses in lupins improved and the results of field experiments involving potential control measures became available. The individual measures combined within the integrated management strategy for each virus were: sowing seed stocks with minimal virus contents, sowing cultivars with inherently low seed transmission rates and isolation from neighbouring lupin crops (CMV only); perimeter non-host barriers and avoiding fields with large perimeter : area ratios (BYMV only); nobreak promoting early canopy development, generating high plant densities, adjusting row spacing, direct drilling into retained stubble, sowing early maturing cultivars, maximising weed control and crop rotation (both viruses). Recommendations to apply insecticide were included solely for spraying high value seed crops (CMV only) or virus-infected pastures next to crops (BYMV only). The justification for selection of each individual control measure, its mode of action in either removing or minimising the virus infection source or suppressing virus spread by aphids and the extent to which it has been adopted by farmers is described. The approach used to transfer the strategies to farmers and the need to avoid complacency following the overall success of the work is emphasised. An integrated disease management strategy developed to clean up the lupin breeding programme from seed-borne virus infection and prevent release of infected seed stocks of new cultivars is also described. It can serve as an example of what is needed to tackle seed-borne virus contamination in other plant breeding or selection programmes. 相似文献
10.
ABSTRACT Take-all, caused by Gaeumannomyces graminis var. tritici, is a damaging disease of wheat that remains difficult to control. The efficacy of an experimental fungicide, applied as a seed treatment, was evaluated in five naturally infested field experiments conducted during three cropping seasons. Plants were sampled and assessed for take-all incidence and severity at different growth stages. Nonlinear models expressing disease variables as a function of degree-days were fitted to the observed data. The incidence equation involved two parameters reflecting the importance of primary and secondary infection cycles. The earliness of infection was identified as an important variable to interpret the effects of the fungicide. In an early epidemic, the fungicide significantly reduced take-all incidence during all or most of the cropping season, whereas in late epidemics, it provided only moderate reductions of incidence. The seed treatment reduced incidence by delaying the primary infection cycle. The fungicide significantly reduced severity during the whole epidemic. It appeared more efficient in limiting root-to-root spread than in slowing down the extension of necrosis on diseased roots. 相似文献
11.
黄瓜花叶病毒CA株系在花生上流行的研究 总被引：5，自引：0，他引：5
据1985~1990年在密云县试验观察,黄瓜花叶病毒(CMV)在花生上流行受病毒种传率、苗期蚜虫发生数量及苗期温度和雨量的影响。花生苗期和花针初期为易感病时期,随后抗性有所增强,但不明显。苗期和花针期发病植株,CMV种传率最高,之后带毒率有所下降。CMV种传率高低与病害流行关系,在同一年份呈极显著正相关关系,而在年度间未达显著水平。花生田间蚜虫发生盛期与病害发生高峰期是吻合的,蚜虫发生数量与病害流行关系显著。根据花生种传率和苗期蚜虫发生数量两因素6年次资料配合的病害流行预测式,其回报可靠度的置信范围在93%左右。 相似文献
12.
The influence of weather and agronomic factors on the activity of six selective herbicides applied at reproductive stages of development for the reduction in seed production of Raphanus raphanistrum in wheat was evaluated. The herbicides used in this way generally reduced seed production by between 80% and 100%. Triasulfuron and mixtures of triasulfuron + MCPA consistently provided the greatest reduction in seed production. This was greater when herbicides were applied at the bud and early flowering stages of R. raphanistrum and the efficacy of the herbicides increased as maximum temperature on the day of spraying increased over the range 14–24°C. An applied model developed from these results predicts the reduction in seed production of R. raphanistrum, for each herbicide, given the stage of weed development and maximum temperature on the day of its application. Wheat yield was significantly reduced as densities of R. raphanistrum increased, with predicted losses at low densities being approximately half of those reported in the literature. There was no consistent evidence that the late application of herbicides had any negative effect on wheat yield through crop injury, nor was there any indication of yield improvement. It is concluded that certain herbicides applied during the reproductive phase of development have considerable potential to reduce R. raphanistrum seed production in wheat crops. As part of an integrated strategy, such late post‐emergence application of selective herbicides to regulate seed production has a likely role for managing weed seedbanks, but little or no value for counteracting weed competition. 相似文献
13.
Knowledge of the ecology of Alliaria petiolata, an alien invasive species in the USA, is essential to predict the efficacy of introduced biological control agents. Accordingly, we examined the growth and reproduction of second‐year A. petiolata rosettes under natural and manipulated density regimes. Plant survival was also studied under natural conditions. Similar survivorship patterns were observed for high‐ and low‐density populations, although survival in the low‐density populations was c. 10% higher. Under natural conditions, low‐density plants were larger and more fecund, on average, than high‐density plants; however, on a per‐area basis, high‐density populations were much more productive. When plant density was experimentally reduced, average seed production and plant size increased with thinning intensity, suggesting that thinning released plants from intra‐specific competition. Additionally, plants in thinned plots were able to recover from past competition and could approach production of the plants in un‐thinned lower density plots that had not experienced prior competition. However, seed production per unit area was lower in thinned versus un‐thinned plots of the same initial density. Results suggest herbivore‐induced plant mortality late in the life cycle, as might occur following the introduction of biological control agents, may reduce the contribution to the A. petiolata seedbank. 相似文献
14.
E. Judenko 《国际虫害防治杂志》2013,59(1):47-53
Wilt caused by the fungus Fusarium oxysporum f. sp. ciceris adversely affects the productivity of cultivated chickpea. For the management of this disease, seed and soil application formulations developed from another fungus, Trichoderma species, were evaluated. In pot experiments, T. harzianum-based formulations Pusa 5SD for seed dressing and Pusa Biopellet (PBP) 10G and Pusa Biogranule (PBG) 5 for soil application, and T. viride-based formulations Pusa 5SD for seed dressing and PBP 4G and PBG 4 for soil application, were found to be highly effective against the disease. A combination of PBP 4G (T. viride) for soil application and Pusa 5SD (T. harzianum) for seed treatment together with a fungicide, carboxin, provided the highest seed germination, shoot and root lengths and grain yield with the lowest incidence of wilt in chickpea under field conditions. Individually, soil application of PBP 4G, and seed treatment with Pusa 5SD were effective in reducing the incidence of wilt and increasing the grain yield of chickpea, but their effectiveness was greater when applied as a combination. Thus, combined application of the formulations of two different species of Trichoderma in two modes of application is recommended for the management of chickpea wilt. 相似文献
15.
ABSTRACT Bacterial blight of onion is a severe disease, which emerged over the past decade in several onion-producing areas. This disease currently is observed in both the Old and New Worlds. Although the causative agent, Xanthomonas axonopodis pv. allii, is potentially seedborne, seed transmission and significance of seedborne initial inoculum for the development of bacterial blight of onion previously has not been assessed. This article describes experimental work designed to evaluate the biological importance of seedborne X. axonopodis pv. allii as an initial inoculum source, and examine the temporal and spatial dynamics of the disease. Over 3 years, outbreaks of bacterial blight of onion always were induced in experimental plots sown with naturally contaminated seed lots, with a contamination rate determined as 0.04%. Analyses of disease patterns indicated a likely seedborne origin for the inoculum associated with the early stages of epidemics. Spatial analyses performed with several statistical methods indicated aggregated patterns of disease incidence data. Primary foci enlarged over time, and a few distinct secondary foci sometimes were established after occurrence of wind-driven rains (with gusts up to 15 m s(-1)). Distances between primary and secondary foci ranged from less than 1 m (satellite foci) to 25 m. It remains possible that longdistance dispersal of inoculum was at least partly involved in the later stages of epidemics. 相似文献
16.
HANWEN WU STEVEN R. WALKER VIKKI A. OSTEN GEOFF ROBINSON 《Weed Biology and Management》2010,10(3):185-193
Field studies were conducted at two locations in southern Queensland, Australia during the 2003–2004 and 2004–2005 growing seasons to determine the differential competitiveness of sorghum (Sorghum bicolor L. Moench) cultivars and crop densities against weeds and the sorghum yield loss due to weeds. Weed competition was investigated by growing sorghum in the presence or absence of a model grass weed, Japanese millet (Echinochloa esculenta). The correlation analyses showed that the early growth traits (height, shoot biomass, and daily growth rate of the shoot biomass) of sorghum adversely affected the height, biomass, and seed production of millet, as measured at maturity. “MR Goldrush” and “Bonus MR” were the most competitive cultivars, resulting in reduced weed biomass, weed density, and weed seed production. The density of sorghum also had a significant effect on the crop's ability to compete with millet. When compared to the density of 4.5 plants per m2, sorghum that was planted at 7.5 plants per m2 suppressed the density, biomass, and seed production of millet by 22%, 27% and 38%, respectively. Millet caused a significant yield loss in comparison with the weed‐free plots. The combined weed‐suppressive effects of the competitive cultivars, such as MR Goldrush, and high crop densities minimized the yield losses from the weeds. These results indicate that sorghum competition against grass weeds can be improved by choosing competitive cultivars and by using a high crop density of >7.5 plants per m2. These non‐chemical options should be included in an integrated weed management program for better weed management, particularly where the control options are limited by the evolution of herbicide resistance. 相似文献
17.
An arable field was subdivided and subjected to either deep inversion ploughing or non‐inversion cultivation after viable seeds of Bromus sterilis had been sown into oilseed rape stubble. After sowing in isolated plots distributed within the field, sequences of cropping treatments for the establishment of two successive winter wheat crops were applied. Each subfield was split into an uphill and a downhill direction for soil cultivation. The field had a 10° slope. In the season following seed introduction, 2.6% of the introduced seeds had successfully germinated and established in the non‐inversion cultivation regime, when no effective graminicide was applied. Ploughing eradicated B. sterilis. Using differential global positioning system (DGPS) mapping of the whole field population, emerged plants were observed up to 8.7 m (uphill treatment) and 21.3 m (downhill treatment) of their initial source. The median distance seeds were transported was 2.3 m uphill and 4.8 m downhill. Post‐emergence application of the herbicide propoxycarbazone slightly reduced weed density and seed weight, and almost halved weed seed production. Application of fenoxaprop‐P‐ethyl was followed by higher density of plants, tillers and seeds of B. sterilis. Seed viability was unaffected by herbicide use. Thus, in the second wheat crop following seed rain, the weed population was dispersed more widely in the field, such that 20–30% of seeds were dispersed more than 5 m distance from the first year's foci of infestation. The relevance of soil cultivation to secondary dispersal of B. sterilis is discussed. 相似文献
18.
19.
Cristina Cabaleiro Antonio Segura 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(4):441-446
With the aim of investigating the dynamics of transmission of GLRaV-3, we report and analyse time-courses of infection incidence
in various plots in one vineyard in Rías Baixas (Galicia, Spain). GLRaV-3 infection was close to 100% after 15 years monitoring
the epidemic in several plots where P. citri was widely spread although with low density populations. In two plots, virus-free plants were planted close to infected ones
and after 8–9 years more than 80% of the plants tested GLRaV-3 positive (average infection rates of 7.8–12.4% per year). The
Gompertz model best fitted the epidemiological data. 相似文献
20.
Masayuki FUJIWARA Miyuki SAKAGUCHI Bo-Song RYAN Satoshi T OHKI Takeshi OSAKI 《Journal of General Plant Pathology》2001,67(2):159-163
Local lesion formation on cowpea leaves was more than 50% inhibited by treatment with a 23 kDa RNase-like glycoprotein from
Cucumis figarei, figaren, from 24 hr before to 1 hr after inoculation with Cucumber mosaic virus (CMV). CMV accumulation detected by ELISA in tobacco leaves treated with figaren 6 or 0 hr before inoculation with CMV was
suppressed. When upper leaves of tobacco plants were treated with figaren and inoculated 10 min later with CMV, mosaic symptoms
were delayed for 5–7 days on most of the tobacco plants, and some plants remained asymptomatic. From fluorescence in situ hybridization, infection sites were present in figaren-treated cowpea or melon leaves after inoculation with CMV, though the
sites were reduced in number and size compared with those in water-treated control leaves. The amount of CMV RNAs and CMV
antigen in melon protoplasts inoculated with CMV and subsequently incubated with figaren similarly increased with time as
did that in the control. ELISA and local lesion assays indicated that CMV infection on the upper surfaces of the leaves of
tobacco, melon, cowpea and C. amaranticolor whose lower surfaces had been treated with figaren 5–10 min before CMV inoculation was almost completely inhibited. Figaren
did not inhibit CMV infection on the opposite untreated leaf halves of melon, cowpea and C. amaranticolor, whereas it almost completely inhibited CMV infection on the untreated halves of leaves of tobacco. CMV infection was not
inhibited in the untreated upper or lower leaves of the four plants. These data suggest that figaren does not completely prevent
CMV invasion but does inhibit the initial infection processes. It may also induce localized acquired resistance in host plants.
Received 10 October 2000/ Accepted in revised form 6 February 2001 相似文献