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Rice (Oryza sativa) seeds were analysed to determine their potential transmission of pathogenic and saprophytic micro-organisms. In four and three hundred lots (stocks) of seeds, in 1998 and 1999 respectively, proceeding from mechanical drying sheds, none presence of Pyricularia oryzae was detected. It did not happen that way for Drechslera spp., whose presence was detected in 8.3% and 28% of the lots, in 1998 and 1999; within these ones the affected seed average was 1.3% in both years. Fusarium sp. appeared in 41% and 48% of the lots, in 1998 and 1999, respectively; the affected seed percentage, within these lots, oscillated between 1.7 and 2.4%. Regarding Arthrobotris sp. and Curvularia sp. the percentage of both, affected stocks and affected seed within these ones, were lower than 2%. About saprophytic micro-organisms, Alternaria appeared in 51% of the stocks in 1998, and in 38% in 1999, while Nigrospora did it in 39% and 33%. The affected seeds average per stock was about 2%. These low seed infection percentage seems a consequence of the mechanical drying process, that disables parts of the inoculum seed. On the other hand, harvested grain samples from trials established to promote the infection of Pyricularia oryzae in 1998, 1999 and 2000, showed that this pathogen was not present in any of these three years, in line with the seed results mentioned above. However, Pyricularia was present in 55% of the harvested grain samples in 2001 trial, as well as in 40% of the seeds. Seed can be a way of transmission of fungi if proceed from campaigns with a high level of inoculum in field.

The occurrence and virulence of wheat yellow rust in Hungary was studied in the period of 1999-2001. Yellow rust in Hungary occurred only in traces in 1999, strongly spread and reached epidemic level in Röjtökmuzsaj (West Hungary) in 2000, and the epidemic explosion was in the whole country in 2001. Surveys of yellow rust showed the importance of pathotypes, whose virulence spectra (virulent for Yr2, Yr3, Yr6, Yr7, Yr8, Yr9, Yr17, YrA+, YrCV, YrSD) were able to math the unknown resistance genes. Among 78 Hungarian and foreign cultivars 29 were strongly infected by yellow rust.

Botrytis cinerea, the cause of grey mould, is a 1999 we conducted trials in order to analyse the efficacy of the pyrimethanil, cyprodinil and fenhexamide and to test sensitivity of B. cinerea to them in vineyard in which these ingredients had been applied intensively, but also in vineyards where they had never been used. Resistant B. cinerea strains to each ingredient were determined in both types of vineyards.

The objective of this study was to establish the genetic relationship among cultivars commonly used as donors for resistance to Plum pox virus (PPV) in order to identify the putative sources of resistance to PPV. The plant material tested represented the European, Central Asian and Chinese ecogeographical groups of cultivated apricots as well as the wild Dzhungar-Zailij population of Prunus armeniaca L. Forty-eight native accessions as well as the resistant (or tolerant) cultivars Harlayne, Stark Early Orange (SEO), Goldrich, Vestar and two hybrid forms Vestar × SEO (LE 3276) and Velkopavlovická × SEO (LE 2904) were screened by means of SSR analysis. To elucidate genetic relationships among apricot germplasm, a dendrogram was produced using neighbor joining (NJ) analysis of Nei's pair-wise genetic distances over 14 polymorphic SSR markers. On the dendrogram, resistant cultivars were separated into two different clusters suggesting two different sources of resistance to PPV. As was expected from pedigrees, SEO, Vestar, LE 2904 and LE 3276 were grouped together in a cluster adjacent to the European cultivars. Resistant cultivars Harlayne and Goldrich were within another group containing Central Asian apricots and Dzhungar-Zailij form.

Surveillance on cyst nematodes in Slovenia started already in 1963. We have found Globodera rostochiensis for the first time in 1971 and for the second time in 1975 (two cysts). In 1999 cysts of yellow potato cyst nematode were found again. A small hot spot was detected along the Slovene Austrian border. Cysts of Globodera rostochiensis were extracted from samples taken in 1.6 hectare field. In 2001 we surveyed 194 fields with the surface of 468.29 ha. We discovered another hot spot of Globodera rostochiensis in the Central Slovenia. Cysts of Globodera achilleae are seldom discovered in Slovenia. During the period between 1980 and 2000 we extracted altogether 206 cysts. In 2001 we found three fields where we extracted at first seven cysts. With more detailed survey we extracted another 30 cysts. In a few soil samples taken from the imported potatoes from Italy we have intercepted cysts of Globodera pallida. For that reason shipments were returned. In a similar way in 2002 shipments from Croatia were returned because of G. rostochiensis presence. Specimens of Globodera rostochiensis and G. achilleae species found in Slovenia were morphometricaly handeled.

The antifungal activity of water extracts of dried leaves of folded blackberry (Rubus plicatus W. et N.), walnut (Juglans regia L.), black currant (Ribes nigrum L.), and aspen (Populus tremula L.) was assessed in the in vitro experiment. The tested fungi were Alternaria alternata, Botrytis cinerea, Rhizoctonia solani, Fusarium culmorum, F. oxysporum and F. solani. It was found that all tested extracts inhibited the development of A. alternaria and F. oxysporum, whereas the strongest inhibiting effect was exhibited by extracts of aspen (A. alternata and F. oxysporum), black current (A. alternata) and folded blackberry (F. oxysporum). The tested extracts had no effect on B. cinerea.

Forma specialis (f.sp.) pisi of Fusarium oxysporum infestates pea but on other crop does not cause. Physiological races of this fungus (races 1, 2, 3 and 6) are tested on differentiation selections of pea. In the mixture with Fusarium solani there was better differentiated the reaction of single races. Own method is based on the artificial infection of the pea with the mixture of conidia and mycelial fragments of the race of Fusarium oxysporum f.sp. pisi and Fusarium solani. The roots of germinating pea are partially shortened on the top and poured with the suspension of fungi. After the germinating the infected pea is placed into Perlit (the substance for the cultivation). The pea was watered after that. During 3 years of our work we tested namely many new selections from the breeding station in Lužany. It seems that some of them should be used for new selection of realy resistant varieties. In the year 1999 there were new selection relatively resistant: 595/32, 682/37, 238/847, in the year 2000 no resistant selections were gained and in the year 2001 there were like resistant evaluated these selections: 633/1409 and 1456/1919.

It is well established that race-specific resistance selects for the specifically matching genes effecting virulence in the pathogen. As well, the use of different R-genes in time makes virulence complexity, VC (the number of virulences per pathogen genotype), to increase. Moreover, it becomes obvious here that the wind-dispersed cereal rusts and mildews are obligate nomads and highly mobile. As a consequence of these points and as a result of modelling, VC was expected to increase in the direction of predominant winds, e.g. from west to east across Europe, and it did by approximately one or more virulences per 1000 km. Starting from the barley mildew pathogen, comprehensive evidence is also available from leaf rust on wheat covering some 5000 km from Western Europe into Siberia. The impact of our findings for population genetics across Europe and Asia is supposed to be considerable and worth further elucidating, e.g., within the 6^th EU Framework Programme.

It was showed that gums induced by Fusarium oxysporum f.sp. tulipae in tulip bulbs applied to mineral Czapek-Dox Broth with Bacto Agar (CzDA) medium, containing sucrose substantially stimulated abundant growth of mycelium and sporulation of the pathogen. Addition of arabinose, xylose and their mixture, sugars occurring in tulip gum polysaccharide, to CzDA medium caused that mycelium was very sparse and sporulation was only slightly stimulated by arabinose. Mycelium growth on mineral CzDA medium without sucrose, was poor and sparse but addition of gum to the medium caused formation of abundant mycelium and increased sporulation of the pathogen. It is possible that polysaccharide of tulip gum may act mainly as elicitor and partially as substrate in regulation of mycelium growth and sporulation of Fusarium oxysporum f.sp. tulipae.

During trials (1998-2001) in the strawberry's plantation of the cv. Marmolade we monitored the appearance of the most important fungal diseases, their biology and possibilities of integrated control. Monitoring the biology of the determined fungi we established the way of overwintering, appearance of fruiting bodies and discharging of spores as well as beginning of primary infection and first symptoms of the following fungi: Mycosphaerella fragariae, Diplocarpon earliana, Gnomonia comari, Phomopsis obscurans on leaves and Botrytis cinerea on fruits. While checking the efficacy of fungicides, those most effecting to leaf diseases were Folicur Multi and Quadris, and on B. cinerea Switch and Teldor. Testing the resistance on botryticides the fungus B. cinerea showed low level of resistance to anilinopyrimidines and phenilsulfamides and high level to dicarboximides.

Systemic induced resistance (SIR) in a plant enhances disease resistance to a broad spectrum of pathogens. Under climate chamber conditions, oxalic acid's ability to elicit SIR in tomato (Lycopersicon esculentum Mill.) against wilt caused by Fusarium oxysporum f.sp. lycopersici (Fol) was tested with a susceptible cultivar (Danish Export). Oxalic acid (OA) was sprayed onto the green part of the tomato plants, at concentrations 2.5, 5, 10, and 20 mM. Two days later, each plant was challenged with 10 ml of Fol suspension (10⁶ conidia/ml) inoculated into the soil around the root system. After inoculation, disease incidence (DI) was quantified visually to assess SIR expression. OA-induced resistance (concentration-dependent) by otherwise susceptible tomato plants was obtained.

Inula viscosa is a perennial plant native to the Mediterranean Basin. Extracts made from the shoots of this plant exhibited a strong fungicidal activity in vitro and in vivo. TLC analyses revealed at least 7 fungicidal compounds. Most are lipophilic. When such extracts were sprayed on the leaf surface of crop plants they effectively controlled downy mildew in grape, cucumber and tobacco; late blight in potato and tomato; gray mold in cucumber and tomato; and, powdery mildew in cucurbits and cereals. Field experiments conducted with grape vine and potato resulted in effective control of Plasmopara viticola and Phytophthora infestans, respectively. The data suggest that Inula viscosa is a useful source of herbal fungicidal preparations for agricultural use.

The incidence of Zucchini yellow mosaic virus (ZYMV) was monitored in the south Moravian region of the Czech Republic during 1997-2001. Crops of gherkin, squash, zucchini and cucumbers were found infected with ZYMV, manifested by symptoms of severe stunting and yellowing with deformed leaves and fruits. Twenty to eighty percent of infected plants were recorded. Six isolates of ZYMV from four localities were differentiated on indicator plants; three of them were maintained as being typical for differences in pathogenicity. Overwintered weed species were tested for the presence of the virus. ZYMV was detected by ELISA in one plant of Tripleurospermum maritimum out of 46 tested, and in two plants of Stellaria media out of 29 tested in 2001. Such tests were repeated in 2002, and ZYMV was detected in three plants of T. maritimum out of 45 tested, in three plants of S. media out of 52, and in two plants of Trifolium repens out of 17 tested. The virus was successfully transmitted from T. maritimum, S. media and T. repens to indicator plants of Cucurbita pepo convar. giromontiina. Back-transmission of ZYMV was proved by ELISA, electron microscopy and symptoms. T. maritimum was found to be a new natural host of ZYMV.

Isolates of Fusarium oxysporum f.sp. ciceri from chickpea (Cicer arietnum L.) can be characterized as races and wilt and yellowing pathotypes by pathogenicity tests on varieties of differentials chickpea. This study shows that, DNA bands generated by RAPD-PCR can be used to assign Fusarium oxysporum f.sp. ciceri isolates to pathotype and pathogenic race.

The main objective of this study was to determinate the occurrence and intensity of attack by the more important fungal diseases on soybean in Eastern Croatia. Four-year investigation (1998-2001) was undertaken on 10 domestic soybean cultivars with different level of disease resistance. The investigation was set in two planting date (optimal and delayed) on experimental fields of the Agricultural Institute Osijek. Following more important diseases were established: Downy mildew, Pod and stem blight and Stem canker. Significant differences in disease incidence were caused by genetic diversity of tested materials as well as different climatic conditions among growing seasons. According to planting date, significantly higher incidence of Downy mildew and Pod and stem blight was in optimal planting date.

Like spores of many fungi, conidia of Blumeria graminis, the powdery mildew fungus of cereals, release extracellular material. It is released within seconds where conidial surface projections touch a leaf. This ECM is probably adhesive since centrifugation showed that forces greater than those due to normal wind speeds are needed to displace conidia. Also, ECM release is probably involved in rapid sensing of substratum contact, leading to germ tube emergence close to the contact site. Thus, ECM release apparently confers at least two benefits to pathogen survival.

Several alterations of growth physiology and bulb formation in garlic (Allium sativum L.) crops, such as "rough" and "burst" bulbs, have been related by different authors with low temperatures during bulbs storage and crop development. These physiopathies affect both the yield and the quality of garlic crops. Incidence of such diseases in Spanish garlic (variety "purple of Las Pedroñeras") were studied during two consecutive years. Experimental design was factorial taking the bulb storage temperature (5°, 10°, 15° and 20°C) as variable factor. Growth indexes during crop development and final quantity of defective bulbs were evaluated. Experimental results show significant differences between treatments, with the higher incidence of both physiopathies in those bulbs stored at 5°C. The 15°C and 20°C storage temperatures clearly reduce the risk of these abiotic diseases and tend to increase the yield and the final quality of the crop.

The genus Armillaria belongs to basidiomycetes and has been known to induce root rot disease and to cause extensive economic losses to a forest crop. We analysed about 40 isolates of Armillaria collected in Czech Republic by PCR and restriction analysis using gel electrophoresis and ion-exchange HPLC. Restrictase Hinf I was able to discriminate all investigated Armillaria species. The sensitivity and resolution of HPLC method was better than that performed by gel electrophoresis. HPLC was able to detect some heterozygous. The results prove the similarity of the species A. borealis, A. cepistipes, A. gallica, A. ostoyae in difference of A. mellea and A. tabescens.

Tan spot, caused by Pyrenophora tritici-repentis (Died.) Drechs., anamorph Drechslera tritici-repentis is one of the most important wheat diseases in the world, especially in the regions of intensive wheat growing. Tan spot had established for the first time in Latvia in 1994. Epidemic of this disease was observed in Latvia in 1998. Development of tan spot were investigated in field experiments at the Research and Training Farm "Peterlauki" of Latvia University of Agriculture in 1998-2001. Level of incidence and severity of tan spot differed depending on varieties and years. Severity of the disease was 16-71% in 1999; 0.1-5% in 2000 and 4-18% in 2001 depending on varieties at the time of ripening. 1999 summer was extremely dry, and development of disease was not observed. Explosion of disease was observed at the second half of June in 2000 and 2001, without reference to varieties. Date of increasing start differed, but in all cases important development was observed after flowering. Rate of increasing of disease was very high, during two weeks severity of disease increased from 0.1 till maximum of severity. Amount and frequency of rainy differed in 2000 and 2001, but increase on disease was very similar, it means, we need more information about favourable conditions for Drechslera tritici-repentis. Sexual stage Pyrenophora tritici-repentis was observed in Latvia for the first time. Further investigations are necessary, because relationships between meteorological conditions and stages of development are unclear.

In the framework of PVS eradication from breeding materials of Czech potato cultivars, the systematic research was devoted to: susceptibility of cultivars, occurrence of PVS in imported and domestic materials, and to maintenance of virus-free basic grades potatoes on breeding stations. In the field-exposure trials was proved high level of susceptibility of most cultivars to PVS and by contraries, gradualy increased proportion of maintained virus-free cultivars of foreign, as well as domestic origin. Nevertheless severe infestation still persist in some of them. The contemporary situation with maintenance of virus-free basic material in CR was demonstrated.

A monitoring system for Cameraria ohridella males based on a synthetic sex pheromone was tested in the Czech Republic, Germany, France and Greece. From the obtained data on the insect phenology we concluded that in Central Europe C. ohridella typically has three generations per year. The pheromone monitoring can be used to detect the pest when it appears in uninfested areas and is also suitable to determine population densities.

Application of the RAPD methods allowed to clearly characterization of isolates of Botrytis fabae and isolates of B. cinerea. Results from RAPD-PCR analysis indicate different groups. Clusters were related with groups based on conidial morphology, morphological characters of the isolates of Botrytis spp.

Apple cultivars were crossed according to the half-diallel and topcross mating design. Apple scab resistance of seedlings was estimated by using a 0-5 scale: 0 - no infection on leaves, 5 - more than 75% of leaf area infected. Percentage of scab resistant seedlings in crosses involving cultivars Prima varied from 35.8% to 67.6%, involving cultivars Florina and Arbat - 51.9-59.5% and 53.5-72.5%, respectively. Significant differences for resistance to scab were found among the crosses. Both general combining ability (GCA) and specific combining ability (SCA) were highly significant. The significance of GCA for scab resistance shows that genetic variability exists for this trait and selection should result in genetic progress, because the mean square for GCA was larger than that calculated for SCA. Therefore, selection of parents on its phenotype should be effective for development of resistant apple cultivars. The significant SCA estimates indicate that a large number of resistant seedlings from particular crosses should be selected.

The resistance of six cultivars of winter oilseed rape (SL 509, SL 507, Darmor, Solida, Jet Neuf, Silesia) against Turnip yellow mosaic virus was studied. The number of over-wintering plants and plants with symptoms of TYMV infection were monitored. All plants were tested by the double diffusion test in agar and by DAS-ELISA to prove infection. ELISA was the most sensitive method, revealing 32-76% of latent virus infections in individual cultivars. The results clearly illustrated that monitoring of plant symptoms is not sufficient to prove TYMV infection in the field and that sensitive, large scale methods like ELISA must be employed to obtain reliable data.

Field resistance can contribute to reductions in epidemic progress of Septoria tritici in winter wheat. Crop growth andcanopy architecture are identified as key mechanisms of field resistance. Near isogenic lines differing for dwarfing (Rht)and photoperiod sensitivity (Ppd) genes, enabled the study of target traits in a constant background of genetic resistance.Epidemics were consistently earlier in shorter crops across a range of environments. The mechanism for this effect wasidentified as an increase in spore arrival due to a reduction in the required dispersal distance between infective tissueand emerging upper culm leaves.

In 1999-2001 in field trials two different apple scab control strategies were compared: (i) the current strategy - conventional disease management (CDM) and (ii) integrated disease management (IDM), according to scab infection periods. A new scab warning equipment METOS^R-D was used for detection of infection periods and forecast of disease intensity at three levels: light, moderate and severe. According to CDM apple-trees were sprayed 9 times a season. Scab warning equipment gave a possibility to optimize the use of fungicides against scab and to reduce the total spray applications per season in average till 6.3 in very susceptible cultivars and 5 in moderately susceptible ones. This is 30 and 44% less spray applications comparing with CDM. Annual spray program ranged from 5 till 8 spray applications of very susceptible cultivars. CDM and IDM gave high scab control in apple-trees and there was not found any essential difference in scab incidence between two control strategies.

Ergot, caused by the fungus Claviceps purpurea (Fr.) Tul., belongs to the main constraints in seed production of Kentucky bluegrass (Poa pratensis L.). The level of ergot occurrence depends on the weather conditions during the growing period, harvest year, storage conditions of seed, and post-harvest treatment. The degree of resistance of the grown cultivar plays an important role. Based on greenhouse trials with four different ergot populations (Zubří, Czech Republic; Leutewitz and Munich, Germany; Pullman, Washington, USA) during 3 years, we found pathogenicity to be one of the most important factors. There were significant differences in the amount of ergot bodies formed between the Central European populations (Zubří, Leutewitz) and the American one from Washington State. The degree of pathogenicity has a major impact on the occurrence of ergot sclerotia in seed of Poa pratensis.

Wheat dwarf virus, a monogemini virus, infects several cereal species. Until now complete sequence data have been published only for wheat isolates. We cloned the complete DNA of 21 isolates from wheat, barley and Lolium spec. and compared the sequences with published data. Two types of the virus were found as previously described. Degree of entire nucleic acid homology between both isolates was in the range of 84%. The Large Intergenic Region showed most pronounced differences while the RepA gene was most conserved. No intermediate forms were found, though both isolates co-existed in the same hosts. Sequence data lead to the suggestion that they should be referred to as different viruses rather than strains of a virus.

In 1999-2001 the investigation of Alternaria species on vegetable crops: cabbage, cucumber, tomato and carrot was carried out and fungi species were isolated from vegetables and substrata used for plant cultivation. Isolated micromycetes: Alternaria alternata, Alternaria tenuissima, Alternaria brassicae, Alternaria brassicicola, Alternaria cucurbitae, Alternaria dauci, Alternaria radicina and Alternaria solani differed in pathogenic peculiarities, frequency of occurrence and their various reaction to fungicides (a.s. azoxystrobin, dichlofluanid, Cooper hydroxide, mancozeb, propamocarb hydrochloride), plant activator Bion (benzothadiazole) and antagonistic microorganisms (Trichoderma harzianum, Streptomyces griseoviridis).