Horizontal (field) resistance to late blight and common scab that is controlled by numerous genes proved to be quite durable in certain potato varieties in Hungarian trials. Although it is difficult to breed for this type of resistance, it has become the preferable strategy in today's breeding programmes, providing long-lasting and less vulnerable protection. Potato breeding in Hungary has produced some promising cultivars such as White Lady, Százszorszép and Rebeka with multiple disease resistance that may play an important role in the Integrated Pest Management (IPM) of near future.

Horizontal resistance to late blight and common scab that is controlled by numerous genes proved to be quite durable in certain potatovarieties in Hungarian trials. Although it is difficult to breed for this type of resistance, it has become the preferable strategy in today's breeding programmes, providing longlasting and less vulnerable protection. Potato breeding in Hungary has produced some promising cultivars such as White Lady, Szazszorszep and Rebeka with multiple disease resistance that may play an important role in the Integrated Pest Management (IPM) of near future.

This thesis describes the genomic localisation and organisation of loci that harbour resistance to the potato cyst nematode species Globodera pallida and G. rostochiensis . Resistance to the potato cyst nematodes G. pallida and G. rostochiensis is an important aspect in potato breeding. To gain insight in the structure of the genes underlying nematode resistance, it is necessary to first map nematode resistance loci, as described for the resistance loci Gpa5 and Gpa6 . Subsequently, both for map-based cloning and for marker-assisted selection, a high-resolution map of theresistance locus is required. A high-resolution map is produced for the H1 locus. To gain more insight in the genomic organisation of a complex disease resistance locus, Gpa2/Rx1 homologues derived from differenthaplotypeshave been characterised. Finally, the Gpa2/Rx1 homologues derived from fivehaplotypeshave been subjected to extensive sequence analysis to elucidate their structural diversity and evolutionary relationships.

In breeding for resistance to late blight, (Phytophthora infestans Mont. de Bary), an economically important disease affecting potatoes, the search for new sources of durable resistance includes the non-host wild Solanum species. The aim of this work was to evaluate the resistance to P. infestans in the somatic hybrids between S. nigrum L. and diploid potato clone ZEL-1136. Sixteen somatic hybrids, their fusion parents, and three standard potato cultivars were screened for resistance to P. infestans in two types of tests--on whole plants and detached leaves--with two highly aggressive and virulent isolates of P. infestans, US8 and MP322. In the whole plant assay, the foliage of the somatic hybrids showed no symptoms of infection, while the foliage of the potato fusion parent and the standard cultivars was infected with P. infestans. In the detached leaflet assay, the breaking-down of resistance of the S. nigrum L. parent and the variable response of individual hybrid clones were noted. Nine S. nigrum L. (+) ZEL-1136 hybrids showed a resistance that was significantly higher than that of S. nigrum, while six clones expressed a resistance to P. infestans similar to that of S. nigrum. The results confirm the effective transfer of late blight resistance of S. nigrum into its somatic hybrids with potato.

Late blight caused by the oomycetous pathogen Phytophthora infestans (Mont.) de Bary is the most important disease of potato crop worldwide. The use of wild species as source of resistance in plant breeding programs has become a great alternative for the control of the disease. In order to identify sources of quantitative resistance among wild Solanum species, 9 species (S. bukasovii, S. bulbocastanum, S. chomatophilum, S. capsicibaccatum, S. megistacrolobum, S. microdontum, S. raphanifolium, S. tarijense and S. verrucosum) were characterized for resistance to late blight in detached leaf assays, greenhouse and field experiments. Six of the selected species showed most of the genotypes free of R-genes, suggesting quantitative resistance to late blight. To identify the genes associated to quantitative resistance, two of these species ( S. megistacrolobum and S. raphanifolium) were characterized with molecular markers. The individuals of each species were grouped according to their phenotypic response in greenhouse in resistant or susceptible. These groups were then analyzed molecularly using ligation mediated polymerase chain reaction with primers obtained from genes involved in plant defense reactions. During this stage, new primers corresponding to genes that are suspected to have a role in plant defense were also designed. Then, the frequency of bands associated with each phenotypic group was tested using x2-test. Finally, some of the bands found significantly associated with one of the phenotypic categories were cloned and sequenced to verify if they correspond to candidate genes of the defense response.

A potato breeding strategy is presented which avoids the common but ineffective practice of intense early-generation visual selection between seedlings in a glasshouse and spaced plants at a seed site. Once pair crosses have been made, progeny tests are used to discard whole progenies before starting conventional within-progeny selection at the unreplicated small-plot stage. Clones are also visually selected from the best progenies for use as parents in the next cycle of crosses whilst they are multiplied to provide enough tubers for assessment of their yield and quality. Mid-parent values, as well as progeny tests, are then used to select between the resultant crosses. Material from other breeding programmes can be included in the parental assessments and used in the next cycle of crosses if superior. Finally, in seeking new cultivars, the number of clones on which to practise selection is increased by sowing more true seed of the best progenies, but without selection until the small-plot stage. Traits considered are resistance to late blight [Phytophthora infestans (Mont.) de Bary] and to the white potato cyst nematode [Globodera pallida (Stone)], fry colour and tuber yield and appearance, as visually assessed by breeders. The theoretical superiority of the strategy for seeking new cultivars lies in being able to practise between-cross selection for a number of economically important traits within 1 or 2 years of making crosses, something that is not possible on individuals as seedlings in the glasshouse or spaced plants at the seed site. This also means that full-sib family selection can be operated on a 3-year cycle, an improvement on current practice of clonal selection on what is often at least a nine-year cycle. New cultivars can be sought with more confidence from the best progenies in each cycle, and modern methods of rapid multiplication used to reduce the number of clonal generations required to find the best clones.

A field trial of 23 stylo taxa was assessed for susceptibility to stylosanthes little leaf (SLL) disease. The trial included Stylosanthes scabra cvv. Seca, Siran, and Fitzroy, S. guianensis var. guianensis cv. Cook, S. hamata cvv. Amiga and Verano and "Stylosanthes seabrana" cvv. Unica and Primar, as well as seven unreleased cultivars from a CSIRO anthracnose resistance breeding program, and four unreleased introduced lines. Plants that had SLL symptoms were sampled on six occasions from March to August 1999 and tested for phytoplasmas, the presumed causal organism of this disease, using the polymerase chain reaction (PCR). All taxa were found to be susceptible to SLL disease except S. hamata cv. Verano and "S. seabrana" cv. Unica. Varieties were ranked on disease incidence, with S. scabra varieties bred for anthracnose resistance having the highest incidence of the disease. These varieties also had significantly higher SLL incidence than that of the original introductions from which they were derived. Before testing, symptom profiles were recorded noting the presence of chlorosis, spike elongation, reddening of leaf tips and floral parts, and reduced leaf size (little leaf). Statistical analysis of the association of these characteristics with SLL disease showed that little leaf was the best disease indicator and that chlorosis and excessive reddening of leaf tips and floral parts were also associated with the disease. The presence of floral abnormalities was also recorded in the symptom profiles. At no time were normal flowers found on samples that had SLL, making this symptom a good indicator of SLL. However, not all plants with floral symptoms tested positive for phytoplasmas by PCR, probably because these symptoms are difficult to diagnose visually. Virescence and phyllody were the most common floral abnormalities and were found to be associated specifically with the phytoplasmas pigeon pea little leaf and sweet potato little leaf variant V4, respectively. An additional floral abnormality, termed abortion, was also observed in association with this disease.

This conference represents a continuation of previous meetings and is intended to bring together active researchers and advisers involved in organic fruit growing to discuss latest results and methods. The main object is the coordination of research and to organize joint research projects. The official language of the workshop is English. Contributions are possible in English and German. Oral presentations will be simultaneously translated to English. --------------------- Table of Contents of the "10th International Conference on Cultivation Technique and Phytopathological Problems in Organic Fruit-Growing and Viticulture 2002": Fruit-growing - Resistance breeding - Breeding apples with durable disease resistance - Yield and Quality of New Scab-Resistant Apple Varieties - Alleyway groundcover management and scab resistant apple varieties Fruit-growing - Insect control - Effect of Quassan, a Quassia product, against Sawflies (Hoplocampa testudinea) - Control of the apple sawfly (Hoplocampa testudinea Klug) with extracts from Quassia amara L: Quality and combination with NeemAzal-TS - Control of Adoxophyes orana FvR with entomopathogens and NeemAzal-TS: first approach for optimal combination strategies Fruit-growing - Control of Sooty blotch - Sooty Blotch of Apple: Etiology and Management - First Examinations to date the exactly Time of Infection of Sooty Blotch - Influence of application strategy of coconut soap on the development of sooty blotch on apple Fruit-growing - Control of post harvest disease - Use of Thermotherapy and Natural Antifungal Compounds against Post Harvest Diseases on Apples - Erste Ergebnisse der Heißwasserbehandlung an ökologisch erzeugten Äpfeln - Efficacy and Pertinence of Heat Treatments against Monilia Decay in Commercial Conditions - Results of an experiment on storage diseases at the apple variety Pinova Fruit-growing - Control of apple scab - The post infection use of lime sulphur to control apple scab Experiences in the Netherlands 1999-2002 - Control of venturia inaequalis: substitutes for and reduced use of copper - Greenhouse-Experiments on control of Venturia inaequalis - First Results - Apfelschorfbekämpfung 2001 unter besonderer Berücksichtigung der Berostung - Mode of action of lime sulphur against apple-scab (Venturia inaequalis) - Inhibition of the germination of conidia from Venturia inaequalis using lime sulphur, sulphur, copper and Ulmasud in comparison to Dithianon Fruit-growing - fruit quality and fruit thinning - Parameters for apple quality and an outline for a new quality concept - Screening of agents for thinning blossoms of apple trees - Neem Azal TS against the cherry fruit moth Argyresthia pruniella L in sour cherry - Results of 5 years of thinning trials with lime sulphur In South Tyrol Viticulture - copper replacement and plant defence - Copper replacement in organic viticulture - state of the art in legislation and research - Biology of Plasmopara viticola - Approach to a biological control of grapevine downy mildew - Induced resistance: a strategy for the control of grape downy mildew? - Grapevine Berry Phenolic Compounds in Relation with Plant Water Status - Disease-resistant vine varieties as a tool to minimize the use of copper Viticulture - copper replacement by use of plant extracts and plant defence - About the use of antagonistic bacteria and fungi - Use of Reynoutria sachalinensis plant extracts, clay preparations and Brovibacillus brevis against fungal diseases of grape berries - Fungicidal preparations from Inula viscosa - Effects of plant extracts on downy mildew of vine-laboratory and field experiments - Evaluation of environmentally friendly products for control of fungal diseases of grapes Viticulture - practical experience in organic viticulture - Effects of different cultivation techniques on vineyard fauna - Kupferreduzierung im ökologischen Weinbau in Deutschland Feldversuche und praktische Erfahrungen - Copper reduction and copper replacement - results and experiences of 12 years on farm research Posters fruit-growing - Undergrowth of late summer sowings at the tree strip - Persistence of the biological effect of codling moth granulovirus in the orchard - preliminary field trials - Influence of fungicides used in organic orchards on the net-photosynthesis of apple trees - Effects of a "Pflanzenstärkungsmittel" on yield influencing factors of apple, first results from the PR China - ´Classy Apple project' to reduce the quality gab between suppley and demand of organic apples - Effect of root pruning on productivity and performance of the apple varieties "Jonagold" and "Elstar" - Main problems and first approach for solutions in organic nursery production - Testing of new strawberry varieties for organic production - Medicinal plants in late blight management of organic potato - Replant problems in South Tyrol: role of fungal pathogens and microbial populations in conventional and organic apple orchards - Organic Horticulture Research at HDRA Posters viticulture - Assay system to screen for compounds inducing PR-gene expression in grape vine (Vitis spec) - Ovules Culture and Plant Formation of Hybrid Progeny of Seedless Grape - Tests with Milsanaâ and Brevibacillus brevis for side-effects against Typhlodromus pyri (Acari, Phytoseiidae) and Aphidius rhopalosiphi (Hymenoptera, Braconidae) - Cueva - a new copper fungicide based on copper salts - Lava Granules - a way to improve the Soil Structure? - Test and valuation of a new system for under-vine cultivation (SIEGWALD HS 1200) in organic viticulture --------------------- For Table of Contents of the 9th Conference ("9. Internationaler Erfahrungsaustausch über Forschungsergebnisse zum Ökologischen Obstbau vom 3.-4. Februar 2000 in Weinsberg" - in German only) see "Additional Abstract" on this web page (full texts available at www.infodienst-mlr.bwl.de/la/lvwo/Veroeff/Erfahrungsaustausch9.htm).