Survey ofPhytophthora infestans populations in Serbia: Mating type, metalaxyl resistance and virulence properties

Summary A total of 37 single-lesion isolates ofPhytophthora infestans were collected during 2000 from different potato growing regions in the central part of Serbia. They were paired in Al and A2 matings to determine their mating types. Of these 37 isolates, 28 were found to belong to the A2 mating type, eight to the Al type and one was found to be self-fertile (A1/A2). Using the in vitro mycelial radial growth method no metalaxyl resistantP. infestans isolate could be found. The rate of occurrence of intermediate isolates was not high, on the average 2.70%. All other isolates were sensitive to metalaxyl. There was no correlation between mating type and the intermediate metalaxyl resistance found.     

黑龙江省马铃薯晚疫病菌对甲霜灵药剂的敏感性测定

利用菌落直径法对2008年黑龙江省4个地区53株马铃薯晚疫病菌的甲霜灵药剂敏感性进行了研究,结果表明,黑龙江省马铃薯晚疫病菌中对甲霜灵药剂具有抗药性的菌株占很大比重,但是区域间抗药菌株的出现频率具有很大差异,其中牡丹江、哈尔滨地区抗药菌株达到了100%,海伦的抗药菌株为23.08%,加格达奇没有出现抗药菌株。本研究对在黑龙江省科学合理地使用苯基酰胺类杀菌剂防治马铃薯晚疫病具有重要意义。     

Incidence of the A2 mating type ofPhytophthora infestans on potato crops in Northern Ireland

Summary Of 250 isolates ofPhytophthora infestans obtained from Northern Ireland potato crops between 1981 and 1993, only six proved to be of the A2 mating type, the remainder being A1. The first A2 isolate was obtained from a tuber in 1987. The frequency of A2 isolates from 1987 onwards was 3%, a lower incidence than has been reported for England and Wales and the Republic of Ireland. There was no association between phenylamide resistance and mating type.     

Wild tuber-bearing species ofSolanum and incidence ofPhytophthora infestans (Mont.) de Bary on the Western slopes of the volcano Nevado de Toluca. 3. Physiological races ofPhytophthora infestans

Summary A survey of races ofPhytophthora infestans was made in 1985 and 1986 on the western slopes of the volcano Nevado de Toluca, Mexico. Isolates were collected from infected plants of wildSolanum species found in five long (7–10 km) and some short (300–500 m) transects. The study are of 15 000 ha was between 2900 and 3900 m altitude. Isolates were collected fromSolanum demissum (35 isolates),verrucosum (11),iopetalum (2),brachycarpum (7),stoloniferum (2), r-genotype (9) and from differential hosts (11). No isolate was identified as race 0. Ten virulence genes were identified with a set of differential hosts and the most common were numbers 2 and 4. Isolates with eight virulence genes were the most common and those with ten were found on eight occasions in the natural habitat and on three in the experimental fields.     

青海省马铃薯品种对晚疫病菌的抗性分析

通过田间自然诱发和室内接种鉴定两种方法,调查评价青海省马铃薯品种对晚疫病的抗性情况。结果显示:所有18个参试品种中均有不同程度的抗病能力。室内鉴定为中抗(MR)以上的品种有8个,占总参试品种的44.44%;感病(S)品种有10个,占总参试品种的55.56%。田间鉴定为中抗(MR)以上的品种有13个,占总参试品种的72.22%;感病(S)品种有5个,占总参试品种的27.78%。室内鉴定和田间鉴定结果相同品种有5个,占总参试品种的27.78%。     

黑龙江省马铃薯晚疫病菌交配型的研究

由致病疫霉Phytophthora infestans(Mont.)de Bary引起的晚疫病是目前危害马铃薯生产最严重的病害之一,明确A2交配型在黑龙江省的存在与否,对晚疫病防治策略的制订具有重要的指导意义。本研究将采自黑龙江省大兴安岭、嫩江、讷河、克山、海伦、绥棱、绥化、巴彦、呼兰、哈尔滨、双城、林口、望奎的马铃薯晚疫病样品进行分离纯化得到124个菌株,通过对峙培养鉴定方法进行交配型测定,结果显示:124个菌株中未发现A2交配型菌株,表明黑龙江省未出现马铃薯晚疫病A2交配型。     

β-氨基丁酸诱导马铃薯叶片晚疫病抗性适宜浓度筛选

β-氨基丁酸(DL-β-aminobutyric acid,BABA)是一种非蛋白氨基酸,能有效诱导多种植物产生对多种病原菌的抗性。为了解BABA处理浓度和时间对马铃薯叶片晚疫病抗性的诱抗效果,本试验用四个浓度梯度(0.5mmol·L~(-1)、1mmol·L~(-1)、2mmol·L~(-1)和4mmol·L~(-1)的BABA喷雾处理马铃薯植株,处理1d、2d、3d和4d后分别取离体叶片接种晚疫病菌。结果表明:在0.5～4mmol·L~(-1)范围,随着BABA浓度增加和处理时间的延长,叶片抗性逐渐增强。2mmol·L~(-1)和4mmol·L~(-1)BABA处理3d后接种,离体叶片晚疫病抗性显著提高。     

Defence reactions in two potato cultivars following infection with two races ofPhytophthora infestans

Summary The kinetics of accumulation of chitinases, glucanases and phytoalexins were studied in two potato cultivars, differing in their degrees of vertical and horizontal resistance, when infected with two races ofPhytophthora infestans. Tuber disks of cvs Kennebec (susceptible, low horizontal resistance) and Huinkul (tolerant, high horizontal resistance) were infected with either race “0” (avirulent) or “C” (complex, race 1.3.5.7.11) ofPhytophthora infestans. Extracts of tuber tissue (0–7 days) from cv. Kennebec infected with race “0” showed a strong increase in phytoalexin production and in chitinase and glucanase activities when compared with those infected with race “C”. These results indicate that race “C” is able to block defensive reactions. No significant differences were observed in cv. Huinkul infected with both races. The contribution of these reactions to horizontal resistance is unknown, and our results would not support a conclusive role for them in the interaction.     

Sites of entry ofphytophthora infestans (Mont.) de Bary into potato tubers in assessment of tuber blight resistance

Summary During assessment of tuber blight resistance using three test methods, the sites of entry ofPhytophthora infestans into the tuber was estimated for 41 cultivars. The trials were conducted using a mix of three highly virulent isolates at Gro? Lüsewitz 1991–1993. The influence of date of harvest and intermediate storage before inoculation was examined with two cultivars in 1993. Two levels of soil moisture and five densities of inoculum were tested in 1994. Methods of assessment of tuber blight resistance, cultivars, years and all their interactions showed a significant effect on sites of entry. Eye infections identified the highest the level of resistance and correlated best with tuber blight resistance in net bag test, r=-0.58. Soil moisture and temperature before harvest varied the ontogenic development of resistance and the relation of sites of entry of the pathogen from July to September. Intermediate storage changed the resistance and the preferred site of cultivar-specific infection. Interactions cultivar x soil moisture and cultivar x density of inoculum were significant and should be considered in the resistance assessment of cultivars.     

Correlation between glasshouse and field tests for resistance to foliage blight caused byPhytophthora infestans

Summary Breeders' selections are assessed for resistance to foliage blight (Phytophthora infestans (Mont.) de Bary) at the Scottish Crop Research Institute in both glasshouse and field tests. In attempts to improve the correlation between the two types of test a number of factors affecting the repeatability of the glasshouse test were examined. ‘Sturdy’ (well-spaced) plants were more resistant than ‘straggly’ (closely spaced) plants; plants inoculated 5, 6 or 7 weeks after planting were more resistant than those inoculated after 4 weeks; and plants grown during the spring were more resistant than those raised in the summer. Factors affecting the correlation between field and glasshouse tests are discussed.

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Zusammenfassung Die Resistenz von Kartoffelklonen gegen Krautf?ule wird in einem Routinetest im Gew?chshaus geprüft. Zwei 5 Wochen alte Pflanzen werden mit einem komplexen Pathotyp vonPhytophthora infestans besprüht, 24 Stunden in einer geschlossenen Kammer bei 15–18°C inkubiert und dann in das Gew?chshaus bei 15°C zurückgebracht. Der Infektionsgrad wird 7 Tage nach der Inokulation mit Hilfe der von Malcolmson (1976) aufgestellten Boniturskala von 1–9 (Resistenz von 1–9 steigend) bestimmt. Die Ergebnisse werden in einem Feldversuch best?tigt. Von jedem Klon werden 2×3 Knollen randomisiert in 50 m langen Reihen gepflanzt. Jede dritte Reihe besteht aus einer anf?lligen Sorte, zwischen die infizierte Pflanzen in T?pfen gestellt werden, um eine Infektionsquelle sicherzustellen. Die Resistenz wird ab Mitte August zwei oder dreimal mit Hilfe der Skala von Malcolmson (1976) bestimmt. über das ganze Feld sind Standardsorten (Tabelle 1) verteilt, als Vergleich für den Infektionsverlauf (Tabelle 4). Pflanzen, die im Gew?chshaus eng zusammengestellt aufwachsen, sind ‘sparrig’ und anf?lliger als weiter-gestellte, ‘buschige’ Pflanzen (Tabelle 2). Pflanzen, die w?hrend des Frühjahrs aufwuchsen, waren resistenter als solche, die w?hrend des Sommers aufwuchsen (Tabelle 3). Wurden sie 4 Wochen nach dem Pflanzen inokuliert waren sie anf?lliger als nach 5, 6 oder 7 Wochen. In jedem Fall waren die resistenteren Bonituren denen im Feld gefundenen n?her. Die Feldergebnisse von zwei aufeinander folgenden Jahren zeigten eine befriedigende Korrelation, zwischen den Ergebnissen für die Prüfung im Gew?chshaus in zwei aufeinander folgenden Jahren und besonders zwischen den ‘Feld’- und ‘Gew?chshaus’-Ergebnissen war sie jedoch geringer. Die Prüfung im Gew?chshaus kann zu einer Untersch?tzung der Resistenz der resistentesten Klone und der Anf?lligkeit der anf?lligsten Klone im Vergleich mit der Feldprüfung führen (Tabelle 4).

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Résumé Des clones de pommes de terre ont été choisis afin d'étudier leur résistance au mildiou sur feuilles par un test de routine en serre. Deux plantes agées de 5 semaines sont pulvérisées avec un complexe dePhytophthora infestans, puis incubées pendant 24 heures dans une enceinte close à 15–18°C, avant d'être mises en serre à 15°C. La gravité de l'infection est mesurée 7 jours après l'inoculation à l'aide de l'échelle 1 à 9 de résistance croissante de Malcolmson (1976). Les résultats en serre sont complétés par une expérimentation de plein champ. Pour chaque clone, deux lots de 3 tubercules sont plantés en randomisation totale sur rangs de 50 m. Tous les trois rangs une variété sensible est plantée et des plantes infectées, en pot, y sont ajoutées afin d'assurer la source de contamination. La résistance est analysée en 2 ou 3 périodes à partir de la miao?t, avec l'échelle de Malcolmson (1976). Des lots de variétés de référence (tableau 1) sont disposés au hazard dans l'essai, dans le but de contr?ler la progression de l'infection (tableau 4). Dans la serre, les plantes plus rapprochées sont plus sensibles au test au moment de la levée que les plantes plus espacées (tableau 2). A la levée au printemps, les plantes sont plus résistantes qu'à la levée en été (tableau 3) et les plantes inoculées 4 semaines après plantation sont plus sensibles que celles infectées 5, 6 ou 7 semaines après. Dans chaque cas, les résistances les plus élevées sont proches des valeurs obtenues en plein champ. Sur deux années successives, les valeurs en plein champ donnent une corrélation satisfaisante, mais sur ces mêmes années, les valeurs ne sont pas autant correlées entre l'expérimentation au champ et le test en serre. Ce dernier semble sous-estimer la résistance des clones les plus résistants et la sensibilité des clones les plus sensibles, par rapport au test de plein champ (tableau 4).

     

Influence of storage temperature on rate of potato tuber tissue infection caused byPhytophthora infestans (mont.) de bary estimated by digital image analysis

Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150 Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day⁻¹ (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from −0.2 ARI day⁻¹ (at 7°C) in all cultivars to a maximum of −0.8 ARI day⁻¹ (10°C).     

Indications of soil borne inoculum ofPhytophthora infestans

Summary In this paper we present observations made during three years in a potato field in Sweden that indicated the presence of soil borne inoculum ofPhytophthora infestans. In 1994, a fungicide trial against late blight was left in the field with various degrees of late blight infection. In 1995, cereals was grown in the field. In 1996, certified potato seed tubers were planted and blight appeared early in the season in a pattern corresponding to the heavily infected areas in 1994. No volunteer potato plants were found in 1995 or 1996. Both mating types A1 and A2 were isolated in 1996 and 1997 and oospores were found in leaves, stems as well as in stolons.     

Phenotypes ofPhytophthora infestans in Nepal: mating types and metalaxyl sensitivity

Summary Potato late blight has appeared in epidemic proportions in Nepal since the mid 1990s and fungicides have been reported to be decreasingly effective in managing the disease.Phytophthora infestans isolates were collected from potato crops during 1999–2000 and analysis of 371 isolates for mating types and 270 isolates for metalaxyl sensitivity revealed the presence of both new and old populations. This is the first report on the presence of metalaxyl-resistant isolates in Nepal. The frequencies of A1 and A2 were 83 and 17%, respectively. Metalaxyl-resistant, intermediate and sensitive isolates were recorded as 10%, 12% and 78% respectively. Metalaxyl resistance was distributed in both mating types. Sites with a history of metalaxyl use had a significantly higher number of resistant and intermediate isolates ({ie337-1}, P<0.01) than sites where metalaxyl had not been used. This study confirms the changes in population structure ofP. infestans in Nepal.     

拌种对马铃薯早疫病、晚疫病及产量的影响

试验以播种前2、3、4、6 d分别用甲基硫菌灵和硫酸链霉素对马铃薯种薯切薯后干拌、湿拌,以不拌种做对照,探讨干拌、湿拌以及拌种后间隔期对马铃薯早疫病、晚疫病田间病薯率及产量的影响。结果显示,药剂的不同拌种方式均能在一定程度上增加马铃薯的产量,干拌的拌种方式增产效果最好,与对照相比平均增产38.05%,播种前2 d切薯并采用药剂干拌对减少田间病薯率效果最明显。     

马铃薯晚疫病抗病基因研究进展

晚疫病是危害马铃薯生产的重要病害,可导致马铃薯的大量减产。多年来研究人员对马铃薯晚疫病进行了大量的研究,取得了一系列的成果。对马铃薯晚疫病防治最有效的方法是使用抗病品种,随着分子生物学技术的发展,从野生资源中分离抗病基因,并将其转入到栽培种马铃薯中可以获得抗病特性。到目前为止,已经有十多个抗晚疫病基因被发现和图谱,且部分基因已被转入到栽培品种中。本文从晚疫病抗病基因的发现、分离、定位及克隆等方面进行了综述。     

黑龙江省马铃薯晚疫病的发生与防治

马铃薯晚疫病是黑龙江省目前主要病害之一,每年发生和流行的程度均不同,但一般年份都会使得马铃薯产量减少20%左右,所以对于马铃薯晚疫病的防治工作越来越被重视。简单介绍马铃薯晚疫病的症状及发病规律,分析黑龙江省马铃薯晚疫病的发生情况,从品种选择、合理轮作、加强田间管理和化学防治等方面,提出综合防治策略和技术,以供种植者参考借鉴。     

Occurrence of the A2 mating type ofPhytophthora infestans in India

Summary One hundred and four isolates ofPhytophthora infestans were collected during 1990–93 from different potato growing regions of India. They were paired with mating type A1 ofP. capsici to determine their mating type. All isolates from the Indo-Gangetic plains and Assam were the A1 mating type, whereas a mixed population of A1 and A2 types occurred at Shillong, Darjeeling and Shimla hills. The frequency of A2 isolates was 5–30% in the Shimla hills and 60% and 58% respectively in the Shillong and Darjeeling hills.     

Screening potatoes for resistance to late blight (Phytophthora infestans) under field conditions

Summary Late blight incidence under natural epiphytotic conditions was recorded on 270 potato germplasm accessions for three years. Replication effect was non-significant, whereas genotype and year effects were significant for AUDPC (area under disease progress curve). Disease incidence on the second date of observation (when the control had almost completely blighted) accounted for 85 to 96 percent of the variation in AUDPC. Spearman’s Rank correlation coefficients between AUDPC and disease incidence grades scored on 1–9 and 1–5 scales (on second date of observation) based on the means of three years data were similar to those calculated based on the means of any two years. It is concluded that grading the accessions based on discrete scales at an appropriate single date for two years in a non-replicated trial would be sufficient robust to broadly group accessions into different levels of resistance to late blight. Ten accessions were found to be highly resistant.     

Peroxidase activity; a potential criterion in breeding for field resistance toPhytophthora infestans

Summary The results of other experiments (cited in the references) showed that peroxidase activity (PA) in clones (cultivars or hybrids) was correlated with field resistance to late blight in uninoculated plants. In contrast, in our experiments where PA was tested in seedlings before inoculation and 5 and 15 days after it, the correlation was found only with PA data recorded after infection. Negative and positive correlations with PA were found, respectively, when the population structure was expressed in four size classes (before inoculation) or of attack intensity (after inoculation).     

马铃薯晚疫病药剂防治试验研究

马铃薯晚疫病是会泽县马铃薯生产上的主要病害。试验开展了马铃薯晚疫病药剂的防治试验,探索不同处理方式,筛选出合适的防治药剂,为马铃薯晚疫病综合防治提供理论依据。结果表明:70%安泰生可湿性粉剂300倍液+68.75%银法利悬浮剂600倍液叶面喷雾2次防治马铃薯晚疫病,防效为76.25%,提高商品率,降低贮藏烂薯率,增产幅度大;68.75%银法利600倍液,每100 kg种薯用4～5kg药液喷湿种薯自然晾干种植,降低防治成本。