首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 140 毫秒
1.
ABSTRACT Cultivar mixtures can reduce potato late blight severity on susceptible cultivars. While alternating rows of susceptible and resistant cultivars would be more acceptable than random mixtures for commercial use, they increase the genotype unit area, which is an unfavorable factor for mixture efficiency, and have been minimally efficient when disease pressure is high. The effects of disease pressure on the performance of alternating rows of cultivars possessing various types and levels of resistance were investigated in 2000 and 2001 near Quito, Ecuador, where natural pressure of late blight is high. The experiments included the highly susceptible cvs. Cecilia in 2000 and LBr37 in 2001, as well as C114 (moderately resistant) and PAN (highly resistant), planted as pure stands and as the three possible two-way combinations. Different disease pressures were obtained with three spraying schedules of a contact fungicide: nontreated, one spray every second week, and one spray weekly. The area under the disease progress curve (AUDPC) on the susceptible cultivar was 0 to 20% less in mixed than in pure plots when no fungicide was applied, 13 to 26% less with a biweekly application of fungicide, and 32 to 53% less with a weekly application. These values are comparable to those obtained in previous experiments in smaller plots with designs maximizing the distance between susceptible plants. No significant differences in mixture performance were observed according to the resistant cultivar included. Effects on yield were minimal, because of the impact of factors other than late blight. Disease pressure therefore appears as a major factor conditioning the efficiency of potato cultivar mixtures against late blight.  相似文献   

2.
Late blight, caused by Phytophthora infestans , is the most severe disease of potato worldwide. Controlling late blight epidemics is difficult, and resistance of host cultivars is either not effective enough, or too easily overcome by the pathogen to be used alone. In field trials conducted for 3 years under natural epidemics, late blight severity was significantly lower in a susceptible cultivar growing in rows alternating with partially resistant cultivars (mixtures) than in unmixed plots of the susceptible cultivar alone. Partially resistant cultivars behaved similarly in unmixed and mixed plots. Mixtures of cultivars reduced disease progress rates and sometimes delayed disease onset over unmixed plots, but did so significantly only for the slowest epidemic. This suggests that reduction of area under the disease progress curve (AUDPC) in mixtures resulted from the cumulative action of minor effects. Disease distribution was focal in all plots at all dates, as shown by Morisita's index values significantly exceeding 1. Significant yield increases for the susceptible cultivar, and occasionally for the partially resistant ones, were observed in mixed-cultivar plots compared with single-cultivar plots. These results show that cultivar mixtures can significantly reduce natural, polycyclic epidemics in broadleaved plants attacked by pathogens causing rapidly expanding lesions.  相似文献   

3.
由致病疫霉引起的马铃薯晚疫病是马铃薯生产中最具危害性的病害,明确现有马铃薯品种(品系)中抗病基因组成情况对于指导抗病品种合理布局及抗病育种具有重要意义。本研究利用农杆菌介导的无毒基因瞬时表达技术分析了致病疫霉8个无毒基因在29个马铃薯品种(品系)中的分布情况。结果表明,品种间抗病基因组成各异,平均每个品种含有4个抗病基因。同时,不同抗病基因在品种中的分布频率也不同,抗病基因R1(76%)、Rpi-blb1(66%)和Rpi-blb2(66%)在品种中分布较普遍;而含抗病基因R3b(45%)、R4(38%)和Rpi-vnt1(34%)的品种较少。此外,品种中所含抗性基因的数量和品种室内抗性程度呈显著正相关(r=0.915 6,P=0.029 1)。  相似文献   

4.
Potato late blight is still an unsolved problem in organic farming. Up to now the disease can only be controlled by copper fungicides. Our project is aiming to reduce the application of copper-containing pesticides by introduction of a blight forecasting system based on meteorological parameters. Primary stem infections should be reduced by seed treatment with copper fungicides thus to postpone the beginning of the blight epidemic as well as the start of spraying. To control secondary infections on the foliage, fungicide strategies should be elaborated to achieve best efficacy with reduced amounts of pesticides. Therefore copper amounts and spraying intervals should be adjusted to the infection pressure. Based on the biological and epidemiological conditions for primary and secondary infections with special emphasis on soil moisture, the potato blight forecast system ÖKO-SIMPHYT should be developed.  相似文献   

5.
ABSTRACT The use of partially resistant cultivars should become an essential component of a sustainable management strategy of potato late blight, caused by Phytophthora infestans. It is therefore important to determine to what extent P. infestans populations can be selected for increased aggressiveness by potato cultivars with different levels of partial resistance. To this end, we sampled P. infestans populations from France and Morocco, chosen as locations where late blight occurs regularly but which differ in the distribution of potato cultivars. Cross-inoculation experiments were used to determine the aggressiveness of all populations to potato cvs. Bintje (prevalent in France but not grown in Morocco) and Désirée (popular in Morocco but cultivated to a very small extent in France). French populations were more aggressive on cv. Bintje than on cv. Désirée, irrespective of the site they were sampled from. Their aggressiveness increased between early and late samplings, suggesting that both cultivars selected for increased aggressiveness during epidemics. By contrast, Moroccan populations were more aggressive on Désirée, regarded as partially resistant in Europe, than on Bintje, highly susceptible under European conditions. These data indicate that P. infestans populations adapt to locally dominant cultivars, irrespective of their resistance levels, and can therefore overcome polygenic, partial resistance. This adaptive pattern may render partial resistance nondurable if not properly managed.  相似文献   

6.
Limiting factors in organic potato production are predominantly nitrogen and infestation with late blight disease (Phytophthora infestans). To maintain high yields, organic nitrogen fertilization, presprouting and control of potato late blight with copper-treatments are potential measures. Field trials were conducted from 2005 to 2007 to evaluate which single measure and combination of measures were most likely to achieve the best results. Organic nitrogen fertilization led to an average yield increase during all three years of trial. Tuber presprouting accelerated plant emergence and also increased yields. It was the most effective single measure, provided that late blight disease appeared (2005 and 2007). In absence of infection with late blight, presprouting had no influence on potato yield (2006). Copper-treatments only had a positive impact on potato yield in combination with optimized plant nutrition and presprouting. Varieties with early tuber development (e.?g. “Princess”) have almost completed formation of yield when infection with late blight sets in. Up to this time, all measures to increase yield should be finished.  相似文献   

7.
Potato production in Ukraine is now mainly in the private sector, and the phytosanitary state of potato crops leaves much to be desired. Control of Leptinotarsa decemlineata is generally well managed, but potato late blight (Phytophthora infestons) is out of control. Potato wart disease continues to cause problems in areas where it occurs because of the unavailability or unacceptability of resistant cultivars. Potato viruses and the losses they cause are little studied or taken into account. Other fungal, bacterial and insect pests are causing increasing problems in the field and in store. Integrated pest management systems are proposed by scientific institutions, including adequate forecasting of potato blight and use of certified seed potatoes of cultivars resistant to wart and cyst nematodes, but these systems do not adequately reach private growers. The range of plant protection products authorized for sale to the general public is very limited, and this is a serious obstacle to adequate plant protection in potato.  相似文献   

8.
The climatological conditions for attack of late blight caused by Phytophthora infestans vary considerably in different parts of Sweden. This is due to the fact that the country is long from south to north covering 14 degrees of latitude from 55 to 69°. One important factor for blight development in Sweden is that potato production is dominated by cultivars susceptible to P. infestans. Approximately 80% of table potatoes are of cvs Bintje and King Edward VII. Cultivars with race-specific resistance such as Bellona, Ukama and Provita are attacked in the whole country. During recent years, many experiments have been carried out to investigate possible reductions in the usage of chemical agents for late blight control. These experiments include choice of fungicide, number of applications, dose rates and treatments according to blight warning systems.  相似文献   

9.
Foliar sprays of potato plants with phosphonic acid (partially neutralised with potassium hydroxide to pH 6.4) substantially reduced infection of the tubers by Phytophthora infestans, the cause of late blight, in glasshouse and field experiments over a 4-year period. Healthy tubers of blight-susceptible cultivars removed from treated plants and artificially inoculated by spraying with sporangial/zoospore suspensions of P infestans did not develop disease symptoms, demonstrating that the phosphonate applications had directly reduced the susceptibility of tubers to infection, probably as a result of translocation into tuber tissue. In contrast, foliar application of fosetyl-aluminium did not significantly reduce tuber blight development following inoculation. Five to six sprays of partially neutralised phosphonic acid (2 kg ha-1) applied at 10-14 day intervals resulted in the least tuber infection, but such a treatment regime may not be economic. In trials where the effect of timing and rate of application of 2-4 kg phosphonic acid ha-1 was examined, a single treatment of 4 kg ha-1 applied mid- or late-season proved the most effective. A spray programme in which one or two applications of phosphonic acid are combined with use of a non-systemic or systemic fungicide to enhance foliar protection offers the possibility of controlling both foliage and tuber blight and could have a major impact in reducing overwinter survival of P infestans in tubers.  相似文献   

10.
Field trials in 1996, 1997 and 1998 with six potato cultivars differing in levels of foliar and tuber race-nonspecific resistance to late blight were treated with 100, 50 and 33% of the recommended dose of the fungicide fluazinam at application intervals of 7, 14 and 21 days. Using a mixed inoculum of six or seven indigenous isolates of Phytophthora infestans small potato plots were inoculated via infector plants. A foliar blight model for the relationship between the effects of resistance, fungicide application and disease pressure was developed using multiple regression analysis. Cultivars with a high level of quantitative resistance offered the greatest potential for fungicide reduction. The model showed that the effect of resistance on integrated control increased exponentially with increasing cultivar resistance. Reducing fungicide input by lowering the dose resulted in less foliar disease than extending application intervals. The higher the disease pressure, the greater the risk associated with reducing fungicide input by extension of application intervals. The field resistance of cultivars to tuber blight mainly determined the frequency of tuber infection. Exploiting high foliar resistance to reduce fungicide input carried a high risk when cultivar resistance to tuber blight was low. When field resistance to tuber blight was high, a medium level of resistance in the foliage could be exploited to reduce fungicide dose to c . 50%, provided application was at the right time. At a high level of field resistance to both foliar and tuber blight, application intervals could be extended.  相似文献   

11.
Field experiments were conducted in 2015 and 2016 to classify the resistance level to early blight of the main potato cultivars in Denmark. A total of 38 cultivars were used. The experiment was designed as a randomized complete block design (RCBD) with four replicates. The potatoes were inoculated by spreading barley (Hordeum vulgare) kernels infested with Alternaria solani and A. alternata. Disease assessment was done at weekly intervals starting from the onset of the first symptoms. The disease progress curves (DPC) of early blight on the cultivars were compared to that of Bintje. A multivariate analysis was performed with the apparent infection rate, the relative area under the disease progress curve, the time to reach 50% severity, the daily defoliation, the disease severity in the middle of the epidemic and the duration of the epidemic to classify the resistance level of the cultivars. The analysis of the DPC of the cultivars showed that none of the cultivars was completely resistant to early blight. However, the epidemic development differed between the different cultivars. The resistance levels of the cultivars were thus classified into classes I, II, III and IV interpreted as ‘very susceptible’, ‘susceptible’, ‘moderately slow blighting’ and ‘slow blighting’, respectively. All the late maturity cultivars were classified as class IV, and the earlier maturing cultivars were either class I or class II.  相似文献   

12.
The mechanism involved in systemic acquired resistance (SAR) can be non-specifically induced in susceptible plants. In response to pathogens, plants' natural defence mechanisms include the production of lignin and phytoalexins and the induction of plant enzymes. The aim of this research was to study the induction of SAR mediated by the chemical activator DL-3-aminobutyric acid (BABA) and the fungicide fosetyl-aluminium in potato cultivars with different levels of resistance against Phytophthora infestans (Mont) de Bary. To study the chemical induction of the resistance, the foliage of several potato cultivars was sprayed with BABA, fosetyl-aluminium or water (as a control treatment). After 3 days the foliage was inoculated with P. infestans. Seven days after inoculation, development of disease symptoms in the foliage was assessed. In postharvest tuber samples, evidence for enhancement of the defence response was evaluated by measuring the protein content of several hydrolytic enzymes as well as the phenol and phytoalexin content. The highest level of protection against late blight was observed when the chemicals were applied at early stages of crop development. An increase in resistance to late blight was also detected in tubers after harvest. There was also an increase in the protein level of beta-1,3-glucanase and aspartic protease as well as in the phenol and phytoalexin content of potato tuber discs obtained from postharvest tubers of treated plants. Thus the protective effect seemed to persist throughout the whole crop cycle. This treatment may offer the possibility of controlling both foliage and tuber blight and could have a major impact in reducing over-winter survival of P. infestans in tubers.  相似文献   

13.
马铃薯晚疫病是严重威胁世界马铃薯生产和粮食安全的重要病害之一,同时也是植物病害中流行速度最快的病害之一。由于品种多不抗病,目前国内外主要依靠化学防治控制该病害。为了提高用药的时效性,将信息技术与植物病害流行学原理相结合,设计并组建了中国马铃薯晚疫病监测预警系统"China-blight"(www.china-blight.net)。该系统由"中国晚疫病实时分布"、"未来48小时不同区域晚疫病菌侵染危险性预测"和"晚疫病化学防治决策支持系统"等子系统构成,此外还包括"晚疫病防治方法"、"品种抗病性"、"化学药剂库"、"其他病虫害"、"问题与经验交流"和"用户田间管理电子档案"等知识信息与服务功能。通过对2009年我国北方马铃薯一作区6-7月份病害侵染时段出现次数与晚疫病实际发生情况进行比较,预测信息与病害实际发生程度相符,该系统可以用于对马铃薯晚疫病田间防治的指导。  相似文献   

14.
During the period 2000–03, local potato cultivars in Estonia, Latvia, Lithuania, Poland and Denmark were tested for foliar resistance to Phytophthora infestans (late blight) in an international field trial network. Four standard cultivars were included in the trials: Sava, Oleva, Danva and Kuras. Primary disease-assessment data were entered into a common database, and parameters from the disease progress curves were calculated and made available on interactive web pages. A regression model, using relative area under disease progress curve (RAUDPC) values for cv. Oleva as a reference, was developed for the estimation of 1–9 scale values, where 1 = most susceptible. Standard deviations for the estimated 1–9 scale values and a nonparametric rank stability analysis of RAUDPC were used to evaluate the stability of resistance of the cultivars. Overall, the results showed stability of resistance for cvs Sava, Oleva and Danva, but not for Kuras. Use of the Internet-based Web-Blight service in this study facilitated comparison of results among countries for the level and stability of resistance. The estimated 1–9 scale values were similar to, or slightly lower than, those from official cultivar lists or from the European Cultivated Potato Database, especially for the more resistant cultivars. Possible reasons for discrepancies from different sources and locations are discussed. It is concluded that RAUPDC and the derived 1–9 scale values are useful for ranking cultivars for resistance to P. infestans , but this information is not detailed enough for use in a decision support system for late blight control.  相似文献   

15.
In an attempt to reduce or eliminate the need for spraying to control potato late blight caused by Phytophthora infestans, investigations were made on the use of controlled-release granules containing the systemic fungicide ofurace. The granules when mixed with sand and buried in soil released the fungitoxicant for about 100 days. When the granules were applied in furrows at planting, protection of potato plants (cv. Maris Bard), assessed by inoculation of detached leaflets with P. infestans, lasted for between 85 and 100 days. Application of the granules when the plants were earthed up 48 days after planting did not result in better late-season protection, possibly due to poorer uptake of the fungitoxicant by the plants at this time. Chemical analysis of leaves from plants that had received in-furrow treatment indicated that ofurace at 0.2–0.5 μg g?1 fresh weight was needed to confer protection from late blight.  相似文献   

16.
In this study, the influence of potato cultivars Irga, Satina, Valfi, Blaue St. Galler and Highland Burgundy Red (HB Red), growth regulators: Bio-Algeen S?90, Kelpak SL and Trifender WP, and the biostimulator Asahi SL on the health status of potato plants and tuber yield was investigated. The severity of late blight and early blight was estimated during the growing season. After harvest, potato tuber yield was determined according to size fractions. The applied treatments significantly reduced the severity of late blight in cv. Irga (Kelpak SL), Valfi (Bio-Algeen S-90, Kelpak SL, Trifender WP) and Blaue St. Galler (Trifender WP) in 2013. In 2015, the symptoms of early blight were significantly reduced in cv. Irga after the application of all tested bioregulators. HB Red was characterized by the best health status among the evaluated cultivars. Kelpak SL and Bio-Algeen S-90 increased the tuber yield of cvs. Irga and HB Red, respectively, in 2013, and Trifender WP increased the tuber yield of cv. Satina in 2014. In the first year of the study, the applied growth regulators and biostimulator significantly increased the percentage of medium-sized tubers of cv. Blaue St. Galler, and Bio-Algeen S-90 increased the percentage of medium-sized tubers of cv. HB Red.  相似文献   

17.
Global severity of potato late blight was estimated by linking two disease forecast models, Blitecast and Simcast, to a climate data base in a geographic information system (GIS). The disease forecast models indirectly estimate late blight severity by determining how many sprays are needed during a growing season as a function of the weather. Global zonation of estimated late blight severity was similar for both forecast models, but Blitecast generally predicted a lower number of sprays. With both forecast models, there were strong differences between potato production zones. Zones of high late blight severity include the tropical highlands, western Europe, the east coast of Canada and northern USA, south-eastern Brazil and central-southern China. Major production zones with a low late blight severity include the western plains in India, where irrigated potato is produced in the cool dry season, north-central China, and the north-western USA. Using a global GIS data base of potato production, the average number of sprays was calculated by country. These averages were compared with estimates of current fungicide use. The results using Blitecast and Simcast were correlated but only Blitecast estimates correlated with observed data for developed countries. The estimated number of sprays, whether from Blitecast or Simcast, did not correlate with the observed number of sprays in developing countries, and in a number of developing countries the predicted optimal number of sprays was much higher than the actual number observed. In these countries, increased access to host resistance and fungicides could have a strong economic impact.  相似文献   

18.
The aggressiveness of 20 Northern Ireland single-lesion isolates of Phytophthora infestans was compared following their inoculation onto detached leaflets of three potato cultivars chosen on the basis of their differing levels of race-nonspecific resistance to late blight: Bintje (highly susceptible); Cara (moderately resistant); and Stirling (more resistant). Five isolates from outside Northern Ireland were included for comparative purposes: two from the Republic of Ireland; two from the USA (representing the US-1 and US-8 clonal lineages); and one from Mexico. To control the variation between tests, a balanced incomplete block design was used, as opposed to either a complete block design or the method of inclusion of standard isolates, where such variation would have increased the error. Highly significant variation for disease parameters, including latent period, infection frequency, area under the lesion expansion curve (AULEC) and sporulation capacity, was found between isolates. These differences were much more marked on the cultivars exhibiting higher levels of race-nonspecific resistance. There was a significant interaction between isolate and cultivar for all parameters assessed and, overall, no one isolate was the most aggressive across all three potato cultivars. However, a group comprising seven of the 20 Northern Ireland isolates was consistently found to exhibit the highest levels of aggression towards all three cultivars for each of the disease parameters. These results demonstrate that significant variation for foliar aggressiveness exists within the Northern Ireland population of P. infestans , and indicate the importance of selecting appropriately aggressive isolates for evaluation of host resistance to late blight within breeding programmes.  相似文献   

19.
ABSTRACT A field study at three highland sites near Quito, Ecuador, was conducted to determine whether host-diversity effects on potato late blight would be as important as recently found in studies conducted in temperate areas. We compared three potato mixtures and use of mixtures in combination with different planting densities and two fungicide regimes. Treatment comparisons were made by absolute and relative measures of host-diversity effects and incorporating a truncated area under the disease progress curve as a means of standardizing comparisons across sites. Potato-faba intercrops consisting of only 10% potato provided an estimate of the effects of dilution of susceptible host tissue. Host-diversity effects were very different across study sites, with a large host-diversity effect for reduced disease only at the site most distant from commercial potato production. Planting density had little influence on host-diversity effects or on late blight in single-genotype stands. Fungicide use in combination with potato mixtures enhanced a host-diversity effect for reduced late blight. Potato-faba intercrops produced only a small decrease in potato late blight. Effects of host diversity on yield were variable, with the greatest increase in yield for mixtures treated with fungicides at the site most distant from commercial potato production. The effects of host diversity on late blight severity may be less consistent in the tropical highlands than in the temperate zone, but can contribute to integrated disease management.  相似文献   

20.
E. Cakir 《EPPO Bulletin》2007,37(2):309-312
Prediction of potato late blight epidemics, caused by Phytophthora infestans (Mont) de Bary, was studied in three different villages of Bolu Province having large potato growing areas with the Winstel and Ullrich Schrodter models in the years 2002–05. During these years, a late blight outbreak was observed only in 2005 with the disease being less apparent in the other years. The Ullrich Schrodter model was found to poorly predict potato late blight epidemics in 2005. The Winstel model gave first warnings too early but correctly predicted late infections. Both the A1 and A2 mating types were found in Central Anatolia for the first time, in Bolu province.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号