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The brown rot fungi of fruit crops (Monilinia spp.): III. Important features of disease management (Review paper)
31-49.Views:292In the third part of this review, important features of disease management are summarised for brown rot fungi of fruit crops (Monilinia fructigena, Monilinia laxa, Monilinia fructicola and Monilia polystroma). Several methods of brown rot disease management practices were collected and interpreted in five main chapters. In these chapters, details are given about the legislative control measures, the cultural, physical, biological and chemical control methods. Chemical control is divided into two parts: pre-harvest and post-harvest chemical control. In addition, host resistance and fungicide resistance statuses are also included in this part of the review. Finally, future aspects of brown rot disease control are discussed.
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The genetic background of resistance to common bacterial blight in newly identified common bean lines on the basis of inheritance studies
77-81.Views:101Common bacterial blight (CBB), caused by Xanthomonas campestris pv. phaseoli (Xcp). is a major disease problem of common bean (Phaseolus vulgaris L.). The inheritance of resistance in Xrl and Xr2 lines to two isolates of Xcp was studied in the F2 and F3 populations from the crosses between these lines and the Masay variety (susceptible to Xcp). Segregation patterns indicated that different single recessive genes presumably in coupling phase linkage determined the resistance to the HUN and EK-1 1 strains of Xcp in both lines. The presence of some minor, modifying genes beside the monogenic genetic background of resistance was also observed. Xrl and Xr2 lines represent valuable new monogenic genetic sources in resistance breeding to CBB.
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Study of genetic resources for Powdery mildew resistance by biochemical and physiological parameters on peaches and nectarines in Romania
57-61.Views:122During 1997-2002, studies on the physiological and biochemical changes due to powdery mildew attack in peach and nectarine cultivars and hybrids belonging to different classes of resistance had been performed at the Research Station for Fruit Tree Growing (RSFTG) Baneasa Bucharest, located in the southern part of Romania. The study was based on disease assessments in the field and on other diagnosis criteria.
The southern part of Romania has favourable ecological conditions for growing peach and nectarine but trees have been attacked by various pathogens such as Sphaerotheca pannosa (Wallr.: Fr.) Lev. var. persicae Woronichin fungus for a long time. The presence of the pathogen causes important changes in the quantity and quality of fruits and affects the metabolism of trees.
This study was focused on several physiological and biochemical parameters such as photosynthesis and respiration intensity along with catalase activity; and changes in some biochemical compounds such as free, total and linked water content, dry matter, nitrogen and protein content, tannin levels. The aim was to find possible correlation among the above parameters and the biotic stress induced by the powdery mildew fungus calculated as attack degree (AD%).
Results showed that photosynthesis diminished significantly in the case of the attacked phenotypes, the respiration was more intense in the infected cultivars and catalase proved to be less intense in the affected plants. The total water content significantly increased in contrast to the dry matter and tannin contents, which greatly reduced in the case of resistant cultivars such as 'Victoria', Vectared 7', 'KB 11-40'. The total nitrogen and protein levels showed less influence on resistance to powdery mildew on all cultivars. All genetic material found resistant to powdery mildew is currently used in peach and nectarine breeding programs in Romania.
Further studies focused on isolation and characterization of resistance genes for powdery mildew resistance will be done in the future based on data collected during several years.
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Historical apple cultivars that display high level of resistance to fire blight
19-23Views:126Following the first outbreak of fire blight caused by the bacterium Erwinia amylovora (Burrill) Winslow et al. in Hungary, we have started research with the aim to screen domestic gene sources, mostly historical Hungarian apple cultivars, for disease resistance as part of an apple breeding program for multiple resistance. The present study was conducted with the aim to choose the most tolerant historical apple cultivars among 25 selected cultivars by screening their behavior towards fire blight under controlled conditions. Six cultivars were shown to be the most disease tolerant: `Batul', 'London pepin', Nemes Sóvári Alma', `Sikulai', `Szemes alma', Wilmos renet'. We evaluated these cultivars by investigating both morphological- characteristics under original environmental circumstances and fruit quality. The cultivars had a remarkable degree of fire blight resistance compared to the control cultivars. These were not competitive with the commercially grown 'Jonathan M40' during cultivar tests but on the basis of certain characteristics they could serve as genetic sources for breeding new varieties.
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Malus taxa and the progenies of Malus floribunda selected in Hungary, as gene sources of resistance breeding
25-28.Views:119One of our objectives in the apple breeding program of the Department of Fruit Science, beside creating new varieties, is to search for new gene sources. After evaluating the disease resistance of Malus taxa available in Hungary, we put the promising selected individuals through further examinations. Their habit and growth vigor was observed, as well as productivity and fruit characteristics were evaluated. Malus fusca seems to be a new, promising gene source in Hungary among the examined taxa. Beside its optimal canopy, growth vigor and fruit characteristics, it has the advantage to be in distant relationship to Malus x domestica, therefore its resistance is based on a different genetic basis. SBG 1 selection of Malus spectabilis can be recommended as a new gene source for resistance breeding. The range of gene sources can further be widened by selected clones of Malus floriblunda (BA I), Malus x zumi (BA) and Malus baccata (SBG 6). An additional value of Malus taxa chosen by us is that they show resistance not only to apple scab, but to powdery mildew as well, and according to our results, they have optimal habit, acceptable productivity and good fruit quality. Nine hybrids were selected from first Malus progenies which proved to be resistant to apple scab and powdery mildew. These are valuable not only as gene sources of breeding, but as pollenizers or ornamental trees, while their decorative fruits can be used in inside decorations and flower arrangements.
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Situation of peach resistance to diseases in Romania
65-69.Views:206The resistance of peach cultivars to the most important diseases caused by fungi, bacteria, viruses and mycoplasms was studied in Romania over two working stages in the period between 1985-2005. The major diseases examined were: Cytospora cincta Sacc., Taphrina deformans (Berk) Tul., Moruluua laxa (Aderh. & Ruhl) Honey, Sphaerotheca pannosa var. persicae Woron., Stigmina carpophila (Lev) M.B.Ellis, Pseudomonas syringae pv. syringae, mycoplasm and plum pox potyvirus. Based on the obtained results, the studied cultivars were classified into resistance groups for the different diseases (very resistant, resistant, medium resistant, sensitive and very sensitive).Based on the results of our study, the following gene sources were chosen following the evaluation of the various genetic material in the peach germoplasm fund, in the climatic conditions of Romania: Cytospora cincta: Cullinan, Cardinal, Hamlet, NJF 3, Onakita Gold, Triumf, "Superba de Toamna", Anderson, Weinberger; Stigmina carpophila: Armgold, ARK 109, Stark Early Blaze, Cardinal, Congres; Taphrina deformans: Madeleine Pouyet, Cumberland, Harbelle, Indian Blood, Sulivan, Victoria, Zafrani, Pekin, Naradnji Ranhii; Spaherotheca pannosa var. persicae: Triumf; Congres; Victoria; Armking; Morton; Regina; Nectared 7; ARK 125; ARK 134; Regina.
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Resistance Gene Analogs (RGA) as a tool in fruit tree's breeding
7-15.Views:175Breeding for pest and disease resistance comes as a major objective behind the fruit traits. To increase the effectiveness of fruit resistance breeding application of the Marker Assisted Selection ( MAS) is advantageous. For generating molecular markers which enable the following of interesting traits basically two methods are available: targeted marker design based on conservative region of already known Resistance ( R) gene sequences or randomly generated markers. The creation and the application of these homology based markers are the object of this review in the main temperate zone fruit species.
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Apple powdery mildew caused by Podosphaera leucotricha: some important features of biology and epidemiology
45-51.Views:344In this review, some important features of biology and epidemiology are summarised for apple powdery mildew (Podosphaera leucotricha). In the first part of the review, the geographical distribution or the pathogen are discussed, then the morphology and taxonomy of the causal organism are described. Disease symptoms or apple powdery mildew are also shown and then host susceptibility/resistance is discussed in relation to durability of resistance. In the second part of this review, the general disease cycle of powdery mildew on apple are demonstrated and some basic features of powdery mildew epidemiology (such response of the pathogen to temperature, relative humidity, and rain as well as spore production, spore dispersal, diurnal patterns and temporal dynamics of the pathogen/disease) are also given on apple host.
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Vegetative Indicators of sour cherry cultivars and resistant clons
55-58.Views:180Sour cherry is a hungaricum. Hungary has several excellent and self fertile sour cherry cultivars. Hungarian sour cherries have a name for fruit quality and they are suitable for fresh consumption. Today breeding is focused not only on fruit quality, but also on disease resistance. The new, investigated cultivars have these characteristics too. But growth characteristics are also very important because they contribute to successful production. The vegetative and generative properties of the cultivars are different. If a cultivar is very productive, the ignorance of cultivar-specific pruning may result in the decrease in tree condition and fruit quality. The properties of producing fruiting wood greatly determine the renewal capabilities of cultivars. Knowing these properties is essential in case of sour cherries, the fruit species that requires a lot of sunlight and tends to produce bare wood. The research of candidate cultivars until now focused on fruit quality. Our aim was to investigate the vegetative characteristics of the resistant ‘bosnyák’ cultivar group in detail, defining the growth characteristics of these cultivars.
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Fire blight (Erwinia amylovora) susceptibility of old Hungarian apple cultivars
35-38.Views:141The aim of the Hungarian apple breeding program started in the Department of Fruit Science was to find resistant apple cultivars against major diseases (scab, powdery mildew, fire blight). The outbreak of fire blight (Erwinia amylovora) in 1996 motivated us to search new resistant sources principally from old traditional apple cultivars. First of all, cultivars have been gathered since 1997 from Carpathia (Visk) and evaluated between 2001 and 2003. In this recent study evaluation of resistance of old Hungarian genotypes to fire blight collected from the English National Fruit Collection (Brogdale, Faversham) is presented.
13 old Hungarian apple cultivars in 2002, and 38 genotypes in 2005 have been evaluated. We used `Idared' and 'Jonathan M41' as susceptible controls and 'Liberty' and 'Remo' as resistant ones. Shoots of two-year-old potted plants were inoculated with a mixture of virulent E. amylovora isolates (Ea2, Ea60, Ea67) at a concentration of 5 x 108 cells/ml. Resistance of apple cultivars was evaluated weekly, four times after inoculation by disease severity of symptoms. Numbers of bacterial colonies in 1 cm length shoot were determined in the fourth week after infection.
8 cultivars in 2002 and 9 cultivars in 2005 displayed notable resistance to fire blight based on one-year data. Based on the coincident data of both years, out of the cultivars collected also from Carpathia ‘Pónyik', and `Sikulai' were found to be resistant and gene sources additional old Hungarian valuable apple genotypes could be selected: `Szabadkai szercsika' and `Tordai piros !davit'. The cultivar `Szemes alma' originated from Visk has proved to be recurrently resistant.
The number of bacterial cells in shoots of the investigated cultivars correlated with the severity of symptoms. With this method, which was introduced by us earlier, we can screen cultivars displaying weak visible symptoms, which cannot be proposed as a source of resistance because of their latent infection.
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General defense system in the plant kingdom III.
45-54.Views:154Our observations regarding the symptoms not fitting into, significantly differing from the hypersensitive defense system, which we noticed during the judgment of several plant species, symptoms provoked on several million plants have constituted a unified entity. They have provided evidence for the existence of a different plant defense system. We called this so far unknown basic response of plants to biotic effects as general defense system. This system defends them from the attack of numerous microbe species in the environment.
The evolutionary intermediate phase between the general and the specific, the two defense systems is the susceptible host—pathogen relation. The vertical resistance system of plants escaping from the susceptible host—pathogen relation, based on specific hypersensitive reaction also suggested the existence of a more original, general defense system and the susceptible host—pathogen relation developed as a result of the collapse of that system.
The evolutionary relation of the two defense systems is proved by the only recessive inheritance of the older general defense system and in the majority of cases dominant hereditary course of the specific defense system. In our experiences, the modifying genes of the recessive general defense system, in most cases, are behind the specific defense systems, which are known to have monogenic dominant hereditary course and react with hypersensitive tissue destruction. This seemingly striking genetic fact is explained by the following: the general defense system less dependent on environmental effects regulates much faster pathophysiological reaction than the specific resistance genes strongly dependant on environmental effects coding dominant hypersensitive reaction.
The general and specific defense reactions, the processes excluding the microbes attacking plants with compacting of cell growth and tissue destruction, which mean two opposite strategies, building on and regulating each other constitute the entity of resistance to plant disease.
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Susceptibility of some traditional pear cultivars of Hungarian and foreign origin to the pathogenic bacterium Erwinia amylovora
41-45.Views:138Fire blight, a disease caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., has been causing serious damage in Hungarian pear plantations since 1996. A prospective control measure could be the use of resistant cultivars. For that purpose ten pear cultivars have been tested under laboratory and greenhouse conditions for resistance to Erwinia amylovora strains collected in Hungary. Six of these cultivars are Hungarian ones of unknown origin, while four are traditional old varieties. Resistant cultivars should serve as germplasm for future breeding. Inoculations were made with a mixture of different pear isolates of the bacteria collected from various growing regions of Hungary (Ea 21, 23), at a density of 5x108 cells/ml. Susceptibility/resistance has been assessed on the basis of intensity of blight symptoms observed on shoots, flower parts and fruits. Cultivars were assigned to three susceptibility groups (low, moderate and high). Complete resistance was not found among the cultivars tested. The highest level of resistance was found in cultivar 'Kieffer', while the other cultivars displayed either moderate or high susceptibility to infection.
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Effect of Erwinia amylovora infection on peroxidase enzyme activity in resistant apple cultivars
37-39.Views:140Two apple cultivars that display enhanced resistance to fire blight (causal agent: Erwinia amylovora) were selected. The aim of the present study was to characterize the peroxidase (POD) enzyme activity of `Szemes alma' (a historical cultivar) and MR-03, (a Hungarian multiresistant hybrid of 'Prima') and compare them to susceptible 'Jonathan M 40' and resistant 'Remo' controls. Peroxides enzyme activity during E. amylovora infections was investigated in artificially infected apple shoots. Increases in enzyme activities were observed in a `Jonathan M40' and in 'Remo', MR-03, `Szemes alma' cultivars. There was a consistent relationship between total enzyme activity and fire blight disease severity. High activity of the peroxidase was positively correlated with the degree of resistance to fire blight. A general hypothesis that POD activity is related to fire blight susceptibility/resistance is supported by our results.
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Impact of foliar fungi on dogroses
23-30.Views:185Wild roses of the section Caninae, commonly known as dogroses, have been described as more disease tolerant than ornamental roses and could therefore become valuable for breeding improved rose cultivars. Two fields with dogroses, one with plants obtained by open pollination in wild populations, and one with plants obtained from intra- and interspecific crosses, were evaluated for blackspot, powdery mildew, rust and leafspots in the autumn of 2005. Symptoms of the different fungi on different dogrose species were carefully evaluated in a microscope and documented by photography. Interestingly, almost no symptoms of powdery mildew were found in either field, although the fungus infected wild roses of a different section in a field closeby. Surprisingly few symptoms were found also of blackspot, and they differed considerably from those found on ornamental cultivars, indicating a lower susceptibility in dogroses. The most important fungal disease in 2005 was rust, followed by leafspot symptoms. The latter were apparently caused by Sphaceloma rosarum and Septoria rosae which can be properly discriminated only in a microscope. The investigated dogrose species and their progeny groups varied significantly in disease susceptibility and in the appearance of encountered symptoms but there was no evidence of major resistance genes, except possibly in Rosa rubiginosa which did not show any symptoms of Septoria. In 2006, a subset of the plant material in Field 1 was evaluated to check for consistency between the years. Leafspots had overtaken rust as the most important disease but results were otherwise very similar to those of 2005.
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Experiments on the Resistance or Pepper Cultivars to Macrophomina phaseolina
74-75.Views:122The ashy stern blight of pepper (Capsicum annuum) is often caused by Macrophomina phaseolina. Serious wilt disease occurred between 1994 and 1996 of pepper plants in Hungary. In 1996-98 screening experiments were made on many pepper cultivars. Culture (Knopp) solution experiments, pot experiments, greenhouse and field trials were carried out. We determined the incidence of disease by visual examinations, testing on PDA culture, and light microscope. There were significant differences in susceptibility of cultivars and breeding materials.
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Fire blight (Erwinia amylovora) resistance in apple varieties associated with molecular markers
53-57.Views:223The invasive bacterial disease fire blight, caused by Erwinia amylovora has the potential to destroy fruit tree orchards all over Europe. Effective plant protection methods are lacking in many countries, highlighting the increasing importance placed on identification of germplasm with heritable disease resistance. Recent l y. a promising QTL (quantitative trait locus) was identified on linkage group 7 in the apple cultivar 'Fiesta· which is derived from ·cox's Orange Pippin' . I n the present study, 144 Swedish and foreign apple cultivars were analysed with the SCAR markers AE I 0-375 and GE-8019. which flank-. this QTL. Twenty-nine of the analysed cultivars had both markers. 78 had either AE I 0-375 or GE-8019, and 37 cultivars did not carry an) of the two markers. Seventeen cultivars. 7 with both markers and I 0 not having either of the two markers, were then inocoluted with the bacterium in a 4uaran1i ne greenhouse test. Cultivars carrying both DNA markers were significantly less susceptible than cultivars lacking the markers, P<0.001. Cultivars that were most resistant had both markers and had 'Cox· in their pedigree. Unrelated cultivars with the markers may still lack the QTL.
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Role of hydrogen peroxide and Pharmaplant-turbo against cucumber powdery mildew fungus under organic and inorganic production
39-44.Views:411Cucumber leaves have been sprayed with a solution of hydrogen peroxide (H202) or Pharmaplant-turbo combined with organic or inorganic fertilizers under plasic house. Under the influence of H202, leaves exhibited resistant against Podoshaera fusca fungus, the causal agent of cucumber powdery mildew. H202 (15 mM) was able to decrease the disease severity from 90.4% to 12% in two experiments conducted in two seasons. Pharmaplant-turbo (Turbo) is new chemical compound and used as an antifungal compound. Turbo in 1 ml/L was able to decrease the disease severity from 90.4% to 11.5% in the both experiments as well. Both of H202 and Turbo were combined with organic treatment (compost + compost tea + seaweed extracts) which showed significant effect against cucumber powdery mildew fungus and strongly suppressed it as compared to control leaves. Organic treatment produced higher vegetative growth characters and greater early and total yields as compared to inorganic treatment, also organic fruits produced the lower nitrate content and the higher ascorbic acid content as compared to inorganic fruits. Our study have indicated that, H202 and Turbo combined with organic fertilizers play a role in the resistance of cucumber against powdery mildew by decreasing the disease severity. We suggest to give more attention to the direct application of H202 in low concentration and Turbo against powdery mildew diseases and other plant diseases.
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Apple powdery mildew caused by Podosphaera leucotricha: some aspects of biology
19-23.Views:348Apple powdery mildew (Podoshphaera leucorticha) occurs wherever apples are grown. One of the most important fungal disease of apple which causing severe econimic loss on susceptible apple cultivars. Biology of the pathogen is widely investigated all over the world in the past 100 years. In this review, a summary from this enormous research is made for biology of apple powdery mildew in the following aspects: geographical distribution, morphology, taxonomy of the causal agent, symptoms, host susceptibility, resistance durability and disease cycle.
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Calla lily soft rot causal agents, symptoms, virulence and management: a review
60-68.Views:110Bacterial soft rot is a polyetiological disease attacking calla lily [Zantedeschia spp (L.) Spreng.]. This disease has reduced the commercial value of this crop. This work aims to review scientific information to give an insight into calla lily soft rot causal agents, symptoms, factors favouring the disease, virulence mechanisms and management strategies. Special emphasis is put on the current progress with regards to understanding calla lily mechanisms of resistance to soft rot and their potential for the development of tolerant/resistant cultivars with commercial traits.
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Preliminary results on salicylic acid treatment on brown rot caused by Monilinia laxa on Jumbo Cot fruit, Prunus armeniaca L.
37-39.Views:256The effect of salicylic acid on reducing brown rot caused by Monilinia laxa infection in postharvest apricot fruit Prunus armeniaca L. Freshly harvest Jumpo Cot fruit were treated with water as control treatment and other group treated with salicylic acid 2 Mm as induced resistance treatment, Fruits were infected by M. laxa (1 × 10-3spores ml-1) and incubated at 25 oC for 2, 4 and 6 days. Treatment fruits with salicylic acid resulted in direct effect on mycelial growth as in the salicylic acid treatment the growth reached to 45% after 6 days of incubation while in the control treatment it reached to 100%.
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Reactions of some cucumber (Cucumis sativus L.) lines and hybrids to zucchini yellow mosaic virus (ZYMV) and selection of tolerant breeding lines
66-68.Views:128In the past years zucchini yellow mosaic virus (ZYMV) has been appeared as a new pathogen of cucurbitaceous plants in Hungary. It caused severe disease outbreaks on the fields of pickling cucumber hybrids which are highly tolerant to cucumber mosaic virus (CMV). Preliminary inoculation tests have showed that all of the important pickling cucumber hybrids produced in Hungary were susceptible to ZYMV-P. However, a selection of Chinese Long and the breeding line I- KS 10C proved to be highly tolerant. The Fl plants of the crosses between the tolerant lines and the susceptible genotype H I were susceptible to ZYMV-P. F2 populations segregated for susceptible and tolerant individuals at a ratio of 3:1. The results strongly suggest that the resistance to ZYMV in our sources is controlled by a single recessive gene. Inoculations of the ZYMV and CMV susceptible cultivar Budai csemege and the CMV tolerant hybrid Perez Fl with the complex of ZYMV+CMV resulted extremely severe symptoms (strong mosaic and necrotic spotting of the leaves) on both cultivars. On the Chinese Long line, which is tolerant to ZYMV and CMV, respectively, the complex of the two viruses caused mild symptoms. The results show a synergistic pathological effect of ZYMV and CMV on differrent cucumber genotypes. More detailed studies on the interactions among the plant genotypes, viruses and virus strains are needed to develop cucumber hybrids that are highly resistant to the ZYMV+CMV complex.
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Anatomical study of the leaves and petioles of scab resistant and susceptible apple cultivars
53-57.Views:134Anatomic studies have been performed on the leaf blade, petiole and annual shoot on six apple cultivars by means of scanning electron as well as light microscope. Four of the cultivars examined are resistant to scab (Florina, Freedom, MR-10, MR-11), whereas two of them are susceptible (Jonathan and Idared). Preliminary results suggest that differences in the width of cross sections of leaf blades, in hairyness, in the shape and size of epidermal cells, moreover, in the cross sections of petioles and shoots are considerable. Some of the anatomical properties seem to be correlated with scab resistance or susceptility of the respective cultivars. Therefore, further studies extending to other cultivars may corroborate our claims to find causal relations between anatomical traits of the leaves and disease, especially scab resistance of apple cultivars.
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Apple powdery mildew caused by Podosphaera leucotricha: some aspects of disease management
29-33.Views:527Apple powdery mildew (Podoshphaera leucorticha) occurs wherever apples are grown. One of the most important fungal disease of apple which causing severe econimic loss on susceptible apple cultivars. This review focuses on the control of apple powdery mildew. The first part of the study provides details of novel aspects of non-chemical control approaches, including agronomic measures, mechanical and biological control options as well as essential features of apple cultivar resistance. After this, developments in chemical control options are described sperately for integrated and organic apple orchards.
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Brown rot blossom blight of pome and stone fruits: symptom, disease cycle, host resistance, and biological control
15-21.Views:823In this paper, important features of symptoms, biology and biological disease management are summarised for brown rot blossom blight fungi of pome and stone fruit crops (Monilinia laxa, Monilinia fructicola and Monilinia mali). Firstly, European brown rot caused by Monilinia laxa is discussed highlighting the blossom epidemiology features, then host susceptibility of the most important stone fruit species including several Hungarian and international cultivars. At the end of this chapter, recent biological control possibilities against Monilinia laxa are also included. Secondly, American brown rot caused by Monilinia fructicola is discussed. Symptoms, biological features of blossom blight and host susceptibility of flowers to Monilinia fructicola are demonstrated. Finally, the symptoms and the biology of the least frequent species, Monilinia mali are shown.
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Reactions of different plant organs of pear cultivars to Erwinia amylovora infection
17-21.Views:123Research project has been initiated in 1999 with the aim of evaluating the degree of susceptibility/resistance of pear cultivars grown in Hungary to fire blight disease caused by Erwinia amylovora. The recently selected promising cultivars were also examined. Inoculation experiments were conducted in controlled greenhouse conditions because of quarantine regulations in Hungary. Following the disease process, development of symptoms of plant organs (shoots, flower parts, fruits) was observed. Suspension of two E. amylovora strains (Ea 21, Ea 23) isolated from pear was used in a mixture (5x108 cells x m1-1) for the inoculation. Twenty-six pear cultivars were examined and grouped into four categories: low susceptibility, moderately susceptible, susceptible and very susceptible. Most of the cultivars were susceptible or very susceptible while some promising 'Eldorado', 'Harrow Delight' and `Hosui' showed low susceptibility.