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• The effect of modified bacterial virulence to host-pathogen relationship (Phaseolus vulgaris L. Pseudomonas savastanoi pv. phaseolicola)

  53-56.

  A. Végvári

  M. Hevesi

  É. Sárdi

  J. Szarka

  I. Velich

  Views:

  191

  The Pseudomonas savastanoi pv. phaseolicola is one of the most expressive biogen stressors of the bean (Phaseolus vulgaris L.) in Hungary. The chemical and agrotechnological defence is inefficient, so breeding is the only workable way. The conventional cultivars are susceptible to PS while most of the new industrial varieties have genetic resistance to the pathogen. The genetic background of resistance is, however, a complex system in the bean. Leaf resistance is a monogenic system, but this gene is not expressed in juvenile stage of the host. The pathogen species can be divided into different races. After inoculation with virulent strains, typical symptoms appeared on the leaves. To understand the details of host-pathogen relationships, there were carried out experiments using bacterial strains with altered virulence. Six transposon mutants of the PS were tested. Our main objective was to test these modified bacterial strains on bean cultivars of known genetic background. First we analysed the symptoms, and then the correlation between the symptoms and the multiplication of mutant bacteria. Three cultivars (Cherokee, Inka and Főnix) were tested.

  The infection by the virulent PS isolate produced typical symptoms on the three cultivars tested. Mutant bacteria (except strain 756) did not cause any significant symptoms on the hosts. The mutant 756 induced visible symptoms on the cultivars Cherokee and Inka. On Cherokee there were small watersoaked lesions, and HR (hypersensitivity reaction) was detected on Inka, but this was restricted to some cells only (mikro HR). The rate of multiplication of the wild type strain was much higher than the multiplication of the mutants. Bacteria were detected in the cotyledons and primordial leaf, but there is not any substantial number of bacteria in leaves, except for strains 757, 1212 and 1213. The rate of multiplication of strain 756 was intermediate. These, and other experiments can help to understand the genetic background of resistance and the host-pathogen relationship in the Pseudomonas-bean pathosystem.

   

• Impact of foliar fungi on dogroses

  23-30.

  C. S. Schwer

  U. Carlson-Nilsson

  Uggla M.

  G. Werlemark

  H. Nybom

  Views:

  188

  Wild 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.

• Sunburn incidence of apples is affected by rootstocks and fruit position within the canopy but not by fruit position on the cluster

  45-51.

  J. Racskó

  Z. Szabó

  D. D. Miller

  M. Soltész

  J. Nyéki

  Views:

  248

  Authors investigated sunburn incidence of apples on the combinations of three different growth inducing rootstocks (M.9,MM.106 and seedling) and five varieties (‘Smoothee’, ‘Golden Reinders’, ‘Granny Smith’, ‘Gloster’ and ‘Jonagold Jonica’). Symptoms were classified as sunburn browning, sunburn necrosis and photooxidative sunburn. The frequency of symptoms was recorded at various parts of the canopy (N, E,W, S, and lower canopy, upper canopy) and on the cluster (terminal, lateral). Cultivar susceptibility varied between 0.30 and 5.65% on M.9 rootstock, ‘Granny Smith’ seemed to be the most susceptible cultivar whereas relatively low percentage of damaged fruit was observed for ‘Gloster’. On MM.106 and seedling rootstocks, damage level was significantly lower than on M.9. Remarkable differences were not observed in the share of the three sunburn types between cultivars. The most common symptom observed was sunburn browning. Far less fruit was affected by sunburn necrosis and photooxidative sunburn. Photooxidative sunburn symptoms were not found on ‘Granny Smith’ and ‘Gloster’ fruits on MM.106 rootstock. Latter cultivar did not show sunburn necrosis symptoms either. With increasing growing vigor of the rootstocks the share of sunburn browning increased. Fruits with sunburn symptoms were found in a great majority on theW quadrant of the trees. This was true for all cultivars. Remarkable differences in the location within the canopy of affected fruits between the three types of sunburn were not observed. Specific distribution of sunburned fruit was observed along the vertical axis of the canopy, too. Most of the damaged fruit were found in the upper canopy. This is particularly true for trees on vigorous stocks such as MM.106 and seedling. On M.9 rootstock, depending on cultivars 5.9 to 38.9% of sunburned fruit was located in the lower canopy. Most common symptom in the lower canopy was the sunburn browning, however symptoms of sunburn necrosis were not found at lower canopy level. Low rate of photooxidative sunburn was observed such lower canopy conditions. Sunburn incidence was very similar on king or side fruit. Significant differences were not found in the share of each sunburn types between fruit positions on the cluster. This was not influenced by rootstocks either.

• Characterization of sunburn damage to apple fruits and leaves

  15-20.

  J. Racskó

  T. Szabó

  J. Nyéki

  M. Soltész

  P. T. Nagy

  Views:

  544

  The specific conditions of the formation of three different types of sunburn (sunburn browning, sunburn necrosis, and photooxidative sunburn) have been recently characterized on apple fruit. However, no information is still available on leaf damage. Therefore, the aims of this study were i) to extend the knowledge on fruit damage, ii) characterize leaf damage and iii) find relationship between fruit and leaf damage. The observations were made on 586 apple accessions in a gene bank orchard located in Hungary. The incidence of the three different types of fruit symptoms were recorded and based on the visual symptoms, two different types of leaf sunburn (sunburn yellowing and sunburn necrosis) were characterized. The most frequent type of fruit sunburn observed was sunburn browning. Photooxidative sunburn was found for less number of accessions, and only some accessions were affected by sunburn necrosis. Fruit were far more susceptible than leaves; (>60%) of the examined accessions were affected by fruit damage and (<3%) by leaf damage. Although a large number of accessions were affected, the percentage of fruit damaged within accessions was not that excessive; ~6% of the fruit assessed showed the symptoms of sunburn browning. Significantly fewer fruit were damaged by sunburn necrosis (~1%) or photooxidative sunburn (~1.4%) than sunburn browning. The percentage of leaves damaged within accessions were simlarly very low (~1%). Close relationship between fruit and leaf damage was found. Accesions with relatively heavily sunburned leaves usually had severe fruit damage as well. Leaves showing sunburn symptoms were usually closely located around those fruit which were sunburned severely. Leaf damage of sunburn was found on spur leaves in a great majority of the accessions damaged, shoot leaves did not seem to be susceptible to sunburn.

• Ascospore dispersal of Venturia inaequalis and subsequent development of scab symptoms in a Hungarian organic apple orchard

  35-37.

  I. J. Holb

  Rózsa A.

  Abonyi F.

  Views:

  254

  In this study, we aimed to study ascospore dispersal of Venturia inaequalis and subsequent disease development in an organic apple orchard (Eperjeske) in 2012 and 2013 on apple cultiva ’Mutsu). Burkard spore trap in March and April were used to monitior ascospore concentration and number of scab symptoms were assesed 20 May in both years. Three peaks were detected in ascospore dispersal in the period of examination which was clearly related to the Mills infection periods. On the basis of the incubation period’s length in April (15–18 days), the appearance of first symptoms had direct connection with the peak of the ascospore discharge. The largest number of symptoms were observed on those parts of the orchards where where the inoculum sources were accumulated.

• Importance of boron in fruit nutrition

  39-44.

  P. T. Nagy

  I. Kincses

  J. Nyéki

  M. Soltész

  Z. Szabó

  Views:

  303

  Boron (B) is an essential micronutrient in plants especially in fruits. Despite of this fact there are very few information about its application, uptake and symptoms in Hungarian fruit growing sector. Nowadays we should consider the effects of weather conditions on soil B availability increasingly according to the climatic anomalies. Identifying of internal and external symptoms of plant parts (leaf, fruit) is help for growers to recognize the deficiency and excess symptoms in time. Methods and application rates of boron fertilization provide further information for growers to achieve qualify-oriented fruit growing among Hungarian conditions. The aim of this minireview is to focus on the importance of boron in fruit nutrition.

• Sunburn assessment: A critical appraisal of methods and techniques for characterizing the damage to apple fruit

  7-14.

  J. Racskó

  Views:

  329

  Many methods and techniques have been introduced for measuring alterations in the fruit and in its surrounding environment related to sunburn incidence. The research objectives, fruit materials and the environment to be evaluated dictate the methods to follow. These procedures are either non-destructive and involve techniques that allow us to track the course of sunburn development and related environmental parameters, or destructive and involve the removal of fruit from the tree for field/laboratory measurements. Techniques employed can be used for pre-symptomatic monitoring (before symptoms become visible) or characterizing the symptoms already present. The principles behind the measurements and their usefulness for sunburn assessments are discussed and critically evaluated in this review paper. Descriptions and evaluations of the methods and techniques were made in the following groups: 1. Thermal measurements; 2. Visual assessments; 3. Fruit quality measurements; 4. Measurements of physiological and biochemical alterations; and 5. Practical evaluation of sunburn damage. Thermal measurements involve methods tracking the ambient temperature and fruit surface temperature, and their relation to sunburn formation. Visual assessments cover all measuring techniques (skin color, chlorophyll fluorescence, radiation reflection, electron microscopy) that are able to detect changes on/in the fruit skin related to sunburn formation. Fruit quality measurements are used to point out differences in qualities (soluble solids, firmness, titratable acidity, and water content) between unaffected and sunburned areas of the fruit. The measurements of physiological and biochemical alterations (gas exchange, pigment analysis, enzyme activity, gene expression) give us a better insight to the mechanism of sunburn formation. Practical evaluations involve many procedures that are used by scientists to characterize the susceptibility of cultivars, evaluate protection technology, etc. For this purpose, the following methods are in use: expressing the percentage of the total fruit surface area affected by sunburn or the percentage of the total number of fruits damaged on the tree, or even a scale based on the severity of the symptoms occurred. All assessing methods and techniques described here have their pros and cons as well as their specific applicability, therefore any of these cannot be favored to use exclusively for assessing sunburn incidence. The combination of these techniques will be the best choice to meet a given research objective perfectly.

• Brown rot blossom blight of pome and stone fruits: symptom, disease cycle, host resistance, and biological control

  15-21.

  I. J. Holb

  Views:

  868

  In 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.

• Incidence of two leaf fungal diseases in two plum training systems

  15-17.

  B. Molnár

  M. Varga

  A. Vámos

  I. J. Holb

  Views:

  446

  In a two-year study, we aimed to determine the susceptibility of four plum cultivars to two fungal pathogens of plum (Stigmina carpophila and Polystigma rubrum) in two training systems with tree spacings of 4 x 1.5m and 6 x 3m. Results showed that shothole symptoms were not detected on cvs ’Bluefre’ and ’Stanley’ in August, 2016. Disease incidence was above 50% in the case of ’Čačanska lepotica’ in both training systems in 2016. There were no significant difference between the two training systems. Shot hole incidence was lower in the 6 x 3m spacings compared to the 4 x 1.5m spacings on cv ’President’ in 2016. Cultivar ’Čačanska lepotica’ showed the highest incidence of Stigmina carpophila in the 4 x 1.5m spacing in 2017. Disease incidence of Stigmina carpophila was significantly lower in the 6 x 3m spacing compared to the 4 x 1.5m spacing. Shothole incidences on cv ’President’ were similar to the values in 2016 ranging from 40% to 60%. Leaf disease incidence was higher in the 4 x 1.5m spacing compared to the 6 x 3m plot. Low disease incidence (below 10%) was observed on cv ’Stanley’ in 2017 and only in the 4 x 1.5m spacing. There were no visible symptoms of blackhorn dotty in 2016 due to inadequate weather conditions for the Polystigma rubrum fungus. However, all the four cultivars were infected by Polystigma rubrum in 2017. The most susceptible cultivar was cv ’Čačanska lepotica’ with the highest disease incidence in the 4 x 1.5m spacing. Disease incidence of this cultivar was lower in the 6 x 3m spacing which was significantly less than in the 4 x 1.5m spacing. The least susceptible cultivar was ’Bluefre’ and symptoms were observed only in the spacing of 4 x 1.5m. The disease incidence of cv ’President’ was similarly low to cv ’Stanley’ in both spacings.

• Fire blight (Erwinia amylovora) susceptibility of old Hungarian apple cultivars

  35-38.

  M. Tóth

  K. Honty

  M. Hevesi

  Views:

  152

  The 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.

• Apple powdery mildew caused by Podosphaera leucotricha: some aspects of biology

  19-23.

  I. Holb

  Views:

  363

  Apple 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.

• General defense system in the plant kingdom III.

  45-54.

  J. Szarka

  E. Sárdi

  E. Szarka

  G. Csilléry

  Views:

  168

  Our 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.

• Some biological features of cherry leaf spot (Blumeriella jaapii) with special reference to cultivar susceptibility

  91-93.

  I. J. Holb

  Views:

  561

  In this review, some important features of biology are summarised for cherry leaf spot (Blumeriella jaapii). In the first part of the review, the geographical distribution of the pathogen and the causal organism are described. Disease symptoms and disease cycle of cherry leaf spot are also shown. Special attention is given to hosts and then several cherry cultivars.are described in relation to their susceptibility to cherry leaf spot.

• Detection of natural infection of Quercus spp. by the chestnut blight fungus (Cryphonectria parasitica) in Hungary

  54-56.

  L. Radócz

  I. J. Holb

  Views:

  200

  The chestnut blight fungus Cryphonectria parasitica (Murrill) Barr [syn.: Endothia parasitica (Murr) Anderson] caused almost total destruction of the American chestnut (Castanea dentata) and widely spread on European chestnut (Castanea saliva) in many European countries. In Hungary, because this fungus threatens most of the Hungarian chestnut stands, great efforts have been made to delay its spread. Biological control with Hungarian hypovirulent strains of the pathogen seems to be an effective method for saving the affected chestnut trees. Until 1998 the fungus was detected on Castanea saliva only, then on some trees of young Quercus petrea in mixed chestnut forests, which also showed the typical symptoms of blight (Kőszeg and Zengővárkony). Although blight symptoms are not so serious in Quercus spp. than in Castanea spp., it seems that C. parasitica threatens the young Quercus spp. in Hungary, mainly in heavily infected chestnut forests. This is the first report of C. parasitica cankers on oak in Hungary.

• Calla lily soft rot causal agents, symptoms, virulence and management: a review

  60-68.

  A. N. Niyokuri

  S. Nyalala

  Views:

  137

  Bacterial 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.

• Studies on the effects of growing substrates and physical factors in sweet pepper forcing in context with the generation of calcium deficiency symptoms

  61-65.

  F. Lantos

  Z. Pék

  Z. Monostori

  L. Helyes

  Views:

  190

  In the publications available for us, exact levels of physical factors and those of the growing technology determining Ca2+ deficiency are rarely detailed. Although the influencing role of the various environmental factors (humidity, light, temperature) is known, we had only little information about their exact values which could be presented for the growing practice. Sweet pepper varieties of the same type grown in various substrates responded to the environmental factors in different ways. Our results revealed that increasing temperature of the root zone had the most significant effect on the incidence of Ca2+ -deficient fruits. Their amount, however, gave different results depending on the growing substrate. In forced sweet pepper grown in soil the proportion of Ca2+ - deficient fruits were significantly lower compared to the plants grown on rockwool. Fruits derived from forcing on perlite, in container were damaged the least by the blossom end rot deficiency symptoms. Our experimental results and technological suggestions are based on measurement results of three years.

• Reactions of some cucumber (Cucumis sativus L.) lines and hybrids to zucchini yellow mosaic virus (ZYMV) and selection of tolerant breeding lines

  66-68.

  P. Salamon

  P. Balogh

  Views:

  139

  In 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.

• Comparative study of heirloom tomato varieties

  31-33.

  J. Oláh

  H. Ledóné Darázsi

  L. Dudás

  Á. Krecz

  D. Parragh

  S. Hodossi

  M. Fári

  Views:

  200

  The study examined the health status, growth type, berry morphology, berry quality, and gastronomical value of 60 heirloom tomato lines. In the middle of June, the level of virus infection was medium in the plant stock according to the assessments. 21% of the lines did not show symptoms of virus infection. During the vegetation period, the major fungal diseases were Alternaria by the middle of August and Phytophthora from the beginning of September. In spite of the fact that no fungicides were applied, 13% of the lines were healthy and 36% showed medium infection at the end of August. Half of the lines had a strong, 23% of the lines had a medium growth vigour. The majority (74%) of the lines showed strong or medium lateral shoot growth and only 7% of them proved to be less prone to branching. In spite of the rapid growth, 20% of the lines had a weak main stem, the majority of the lines had a main stem medium strength. The different shapes occurred in different colours, in addition to the traditional red colour (53%), there were orange, yellow, wine-red (blackish), lilac, green, almost white or multicoloured varieties. Unfortunately, most of the lines were prone to longitudinal or circular cracking of the berries. Based on the first experiences, all tested variety types had more favourable utilization characteristics then the traditional tomatoes. Varieties with a thick flesh and harmonic acid/sugar ratio such as some of the ox-heart varieties are especially valuable. For drying, the elongated types proved to be the best. The hollow tomato is the most special type which can be utilized most diversely. It is especially suitable for making white tomato soup and, “Concasse" due to its easily removable placenta rich in jelly materials and its thick flesh. In addition, it can be used for preparing stuffed tomato.

• Drought stress monitoring by laboratory and satellite spectral methods in an apple orchard

  7-9.

  A. Nagy

  P. Riczu

  J. Tamás

  Views:

  240

  An orchard can be examined on the basis of spectral data, using such methods with which the reflected radiation can be divided into a large number of (several hundreds) small spectral channel (some nm). Based on the spectral characteristics of the canopy, or the different index numbers calculated from hyperspectral data the water supply conditions of foliage can be well characterized. The research site is an intensive apple orchard, which located in Debrecen University, Centre for Agricultural and Applied Economic Sciences, Farm and Regional Research Institute at Pallag. During our experiments the evaluation of spectral, non-invasive measurement method are carried out for detecting stress symptoms caused by drought. Furthermore, MODIS NDVI time series data were analyzed for orchards situated in North-Eastern part of Hungary in drought effected and wet years in order to detect differences. Significant differences in NDVI values were detected after the end of June.

• Mathematical and Statistical Modelling of Impact Symptoms and Application to Tomato

  75-80.

  B. Herold

  B. Oberbarnscheidt

  F. Jakovác

  L. Kovács

  B. Borsa

  Views:

  112

  Drop tests were performed with different tomato cultivars. „Rupture" and „no rupture" conditions were determined as results. The proportion of „rupture" was shown versus the drop height and the relationships were described by a logistic function. The different cultivars are compared on this basis. The tests and results are suitable for the evaluation of stress sensitivity of tomatoes.

• The microscopic fungi of orchid species in the Őrség National Park

  31-36.

  L. Jandrasits

  G. Fischl

  Views:

  176

  The wild orchids growing in Hungary are some of the most decorative and interesting members of the country's flora. The majority of species are rarely spotted, and some are only found in very few habitats, though others are quite common .All the species known in Hungary are protected, and 1 1 species are strictly protected. Itis thus important to monitor the health status of these plants, to determine what diseases affect them, what pathogens are found on them and how severely they are infected, and to take the necessary precautionary measures. Eleven of the 14 orchid species occurring in the 6rseg National Park were included in the study and the presence of microscopic fungi was detected on eight of these. Pathogenic species were found on lesser butterfly orchid (Platanthera bifolia), green-winged orchid (Orchis morio), burnt orchid (Orchis ustulara), sword-leaved helleborine (Cephalanthera longifolia), common twayblade (Listera ovata), autumn lady's-tresses (Spiranthes spiralis), western marsh orchid (Dacrylorhiza majalis) and broad-leaved helleborine (Epipactis helleborine). A detailed account is given of the symptoms of major diseases and of the microscopic traits of the pathogens. An attempt was made to determine to what extent the pathogenic fungal species found on protected orchid species influence the lives of these plants. Current knowledge on this subject is extremely deficient, as practically no data are available from Hungary.

• Micro area based spatial distribution of apple scab in an organic apple orchard

  21-23.

  I. J. Holb

  P. Lakatos

  F. Abonyi

  Views:

  225

  In this study, the objective was to report a two-year investigation on micro area based spatial distribution of apple scab in an organic apple orchard. Results showed that number of symptomatic plant part ranged between 587 and 623 on leaf and between 46 and 78 on fruit for an individual tree. Number of asymptomatic plant part ranged between 1034 and 1321 on leaf and between 119 and 193 on fruit. Disease incidence ranged between 35 and 40% on leaf and between 27 and 33% on fruit. Disease aggregation index ranged between 0.115 and 0.298 on leaf and between 0.117 and 0.221 on fruit. Three of the four trees showed significant within canopy aggregation of disease for leaf apple scab symptoms in both years. For fruit apple scab, two of the four trees showed significant random patterns in both years.

• The impact of location, row direction, plant density and rootstock on the sunburn damage of apple cultivars

  19-30.

  J. Racskó

  J. Nagy

  Z. Szabó

  M. Major

  J. Nyéki

  Views:

  326

  The effect of row direction (N-S, E-W), plant density (conventional and intensive) and rootstock (M9, MM106 and crab apple) on the sensitivity of 41 apple cultivars to sunburn injury was studied at 6 locations (Derecske, Kálmánáaza, Nagykutas, Nagylapos, Siófok, Tornyospálca).

  During the observations the cultivars had rootstock-specific properties in respect of sunburn-susceptibility. Accordingly, the injury was decreased in the order: M9, MM106 and seedling rootstocks. The differences in sensitivity depend on the canopy of trees, caused finally by the growing vigour of rootstocks. Accordingly, the highest value of sunburn injury was observed on M9 rootstock, because this rootstock has a dwarfing effect upon the scion cultivars. Thus, vegetative area of these trees grow very slowly and the foliage is not enough compact to protect the fruit from solar radiation. The size and density of the foliage increased in the order: M9, MM 106 and crab apple seedling as rootstock. Moreover, relationships were demonstrated between the diameter of upper part of the crown, the leaf area, the number of fruits per tree and the injury of sunburn.

  Authors categorized the cultivars in respect of values of sunburn incidence: 1. „Not sensitive", II. „Moderately sensitive" and HI. „Strongly sensitive" categories were constituted. Generally, Topaz and Gala cultivars showed low damage (or were free from symptoms), in contrast to this, Golden mutants suffered relatively much. The most sensitive cultivar was Jonica on all the three rootstocks. We searched for relationship between the fruit quality parameters and the frequency of sunburn. Significant correlation was found in the cases of fruit size and the extent of cover-colour. The latter is interpreted with the fact that the best coloured fruits are found on the periphery of crown as a consequence of more intense irradiation.

• Prevalence of banana diseases and post-harvest losses in Kenya, and biocontrol potential of arbuscular mycorrhizal fungi against Fusarium wiltngi Against Fusarium wilt

  62-73.

  H. K. Kamore

  E. M. Njeru

  S. B. Nchore

  R. O. Ombori

  J. M. Muthini

  J. Kimiti

  Views:

  5

  The demand for bananas (Musa spp.), which is ranked as the most important fruit crop in Kenya has been on the rise owing to both their dietary contribution and income generation. Meeting this demand has however been hampered by losses during production or post-harvest. This study assessed banana disease and post-harvest losses in leading producing counties in Kenya namely; Kisii, Nyamira and Embu. The study also assessed the efficacy of Rhizophagus irregularis in controlling Fusarium oxysporum f.sp. cubense. Structured questionnaires were used to collect data on post-harvest losses. Disease scoring tables, charts and photos were used to confirm observed symptoms and hence, disease occurrence and severity. AMF biocontrol efficacy experiment was conducted using tissue culture bananas grown in the greenhouse. The study revealed that most smallholder farmers were unaware of the causes or the prevalence of post-harvest losses. The findings also revealed a significant difference (p<0.05) in the severity of banana diseases across various cultivars from the three counties. The AMF treated bananas showed a significant difference (p<0.05) in plant height, total leaf area and chlorosis in comparison to other treatments. The study also revealed a reduction of Fusarium’s pathogenic effects including chlorosis, reduced leaf surface area and eventual necrosis.

• In vitro comparative study of two Arundo donax L. ecotypes’ selenium tolerance

  119-122.

  É. Domokos-Szabolcsy

  N. Abdalla

  T. Alshaal

  A. Sztrik

  L. Márton

  H. El-Ramady

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  302

  Selenium tolerance of two somatic embryo-derived Arundo donax L. ecotypes (Blossom, 20SZ) were compared in in vitro culture. Sodium-selenate (1 – 100 mg L-1) as known the most phytoavailable selenium form and the less studied red elemental nanoselenium (100 mg L-1) were applied as selenium treatments. Basis on the results Blossom ecotype seemed to be more sensitive to the sodium-selenate than 20SZ. Inhibiting effect of selenate was effectuated above 10 mg L-1 in case of Blossom, which was manifested in decreased survival rate and growing parameters. Contrast to this 20SZ could tolerate the selenate ≤ 20 mg L-1 without any toxic symptoms. Lower selenate tolerance of Blossom could be explained with higher selenium accumulation. Both of two ecotypes could also uptake and accumulate the red elemental nanoselenium however in much less extent compared to selenate.