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Ditylenchus dipsaci is one of the most harmful parasitic nematodes in Central Europe. It is able to survive for long time in soil without its host plants and that is why it belongs to organisms with quarantine importance. Nothing is known about D. dipsaci distribution in the Czech Republic. The aim of the study was to collect samples of D. dipsaci from the Czech Republic and to identify them by molecular methods. Region of rDNA including 3'end of 18 S gene, ITS1, 5,8 S gene, ITS2 and 5'end of 26 S gene was amplified using general primers designed according to the DNA sequence of Caenorhabditis elegans. The amplicon (900 bp) was analyzed by RFLP and SSCP. Restriction endonucleases Eco R1, Hinc II and Alu 1 can be used for differentiation of certain bioraces of D. dipsaci. At the same time methods for DNA extraction from plant material and contaminated soil were optimized.

The interaction between Plasmodiophora brassicae and its host Brassica rapa is investigated by two strategies. (1) IAA-conjugate hydrolases: Root hypertrophy in club root disease is dependent on increased auxin levels and these could result from auxin-conjugate hydrolysis. So far we isolated 5 different cDNA fragments out of various tissues which revealed high identity to IAR3/ILL5, ILL2, ILL3, ILL6 and ILR1 genes from Arabidopsis by comparison with database entries. (2) Random priming: Using this method, we have so far obtained 26 clones from clubroot tissue, from which several sequences may be components of plant signal transduction chains, metabolic pathways and transcriptional regulation.

Population studies and tests on the relationship between density and damage were conducted in 1999 to 2001 to determine the pest status of Empoasca dolichi on groundnut (Arachis hypogaea L.) in the Zaria area of northern Nigeria. Analyses showed that Empoasca numbers varied significantly from one year to another, and within each year the numbers of leafhoppers observed at the different growth stages of the plant were significantly different (P = 0.01). There was an inverse and highly significant relationship between the mean kernel yield and the Empoasca damage at the different growth stages of the plant. When natural population densities were plotted against economic injury level (EIL), the densities did not reach the EIL throughout the groundnut growing seasons. The insect was thus not an economic pest on groundnut in Zaria during the period of the study.

The bacterium Pseudomonas savastanoi pv. nerii was identified as the causal agent of parenchymatous galls on leaves of potted oleander plants grown at Brno, Moravia, in 2004. The plants had originated from cuttings made from firm shoots of a supposedly asymptomatic plant grown in and introduced from the Mediterranean region. The Biolog GN microplate system was used to identify the isolated bacterial strains. Successful inoculation of Nerium oleander seedlings proved the pathogenicity of the isolates. This is the first record of P. savastanoi pv. nerii in the Czech Republic. :

An unusual disorder occurred on spring barley seedlings in southern and central Bohemia in April 2005. Affected seedlings showed conspicuous bleached or straw-coloured areas on tips of the first leaves. There were very sharp, distinct, horizontal boundaries between the green basal and discoloured tip parts of the leaves. It was remarkable that these boundaries were at the same position on all affected first leaves of seedlings from the same field. Affected seedlings were randomly distributed in the fields, and their incidence ranged from about 20 to 70% according to location. Based on meteorological data it can be concluded that the colour abnormality in emerging seedlings was associated with specific environmental stresses, being effective in certain chronological order on sensitive plant tissues during the period from 6 to 8 days after seeding. These stresses include frosty mornings followed by clear days with high solar radiation with a high UV Index.

The mortality of pupae in stems lying on the ground during hibernation was 51.7% in 2003. The emergence of adults in 2003 and 2004 was monitored from late April to early July by photoeclectors placed on fields that grew poppy the previous year. Most adult gall wasps emerged in April to early May 2004. The occurrence of females ovipositing on poppy stems varied from April to July and the degree of damage to the plants increased. Most frequently the females oviposited in the first stem internodes. The infestation of poppy cultures with the gall wasps was almost uniform, the number of infested plants increasing still in June. In late June, only seven out of 600 plants were not infested. Green sticks covered with non-coagulating glue and placed in the poppy field, indicated the stem heights frequented by ovipositing females. The gall wasp larvae were parasitised by Trichomalus bracteatus Walker and Pseudotorymus papaveris Ruschka, with T. bracteatus predominating. Most frequently, gall wasp larvae inside the seventh internode were parasitised by this species.

The species composition, frequency and abundance of insect pests (Coleoptera) occurring outside a grain store were explored. Wheat bait traps were used for pest monitoring; they were changed every month from April to September. For the first time the outdoor occurrence of primary and secondary stored-product pests was documented in the Czech Republic. Seven species of Coleoptera were found outside the grain store. Pest abundance and frequency were in high correlation. The primary pest Sitophilus granarius was dominant.

The response of 25 registered winter wheat varieties to autumnal infection with Wheat dwarf virus (WDV) was studied in small plot trials in two years. The materials were infected by vectors, leafhopper Psammotettix alienus Dahlbom, 1851 from three-leaf stage to tillering. The symptoms expression was monitored in spring and plant height, weight of above ground biomass and grain yield were observed in summer. All tested varieties were evaluated as susceptible and divided into three groups: varieties Banquet and Svitava with 87.3-93.1% grain yield reduction as moderately susceptible, varieties Clever, Drifter, Niagara and Rialto with 95.6-97.68% grain yield reduction as susceptible and varieties Apache, Batis, Bill, Complet, Contra, Corsaire, Ludwig, Mladka, Nela, Record, Rheia, Semper, Sepstra, Solara, Sulamit, Tower, Trend, Vlasta and Winsdor with 99.7-100% grain yield reduction as very susceptible. Statistically significant differences were observed between moderately susceptible and susceptible varieties as well as very susceptible ones in absorbency values by means of DAS-ELISA.

Hop downy mildew (Pseudoperonospora humuli) and hop powdery mildew (Podosphaera macularis) are the most important pathogens of hop (Humulus lupulus). The early detection and identification of these pathogens are often made difficult by symptomless or combined infection with another pathogens. Molecular analysis of internal transcribed spacer (ITS) regions of rDNA is a novel and very effective method of species determination. Therefore, specific PCR assays were developed to detect the pathogens Pseudoperonospora humuli and Podosphaera macularis in naturally infected hop plants. The specific PCR primer combinations P1 + P2 and S1 + S2 amplified specific fragments from Pseudoperonospora humuli and Podosphaera macularis, respectively, and did not cross-react with hop DNA nor with DNA from other fungi. PCR primer combinations R1 + R2 and R3 + R4 could be used in multiplex PCR detection of Pseudoperonospora humuli, Podosphaera macularis, Verticillium albo-atrum and Fusarium sambucinum. Phylogenetic relationships were inferred for 42 species of the Erysiphales from nuclear rDNA (ITS1, 5.8S, ITS2). The molecular characterisation and phylogenetic analyses confirmed the species identification of hop powdery mildew. The PCR assays used in this study proved to be accurate and sensitive for detection, identification, classification and disease-monitoring of the major hop pathogens.

The incidence of fungi on caraway (Carum carvi L.), fennel (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.) and anise (Pimpinella anisum L.) was observed on several localities in the Czech Republic. Incidence of 26 parasitic and saprophytic fungi were found on fennel, 35 species on coriander, 21 species on anise and 34 species on caraway. Small plot trials of spices were evaluated during the whole growing season. The fungicides in caraway were applied in different growth stages. The test results showed high effectiveness of autumn and early spring applications on the most dangerous pathogen of caraway - Mycocentrospora acerina. Three fungicides were tested in fennel field trials showing sufficient force against pathogenic fungus Cercosporidium punctum. The complex of root fungi causes the serious damage of coriander. Foliar application of fungicides did not present adequate effect. Four growth regulators were tested, but all of them increased incidence of fungi Fusarium sp. and Alternaria alternata.

Ascospore progeny of cross of Pyrenophora teres f. teres isolates was evaluated on virulence to three barley genotypes. Monogenic inheritance of virulence (26 a:17 v and 31 a:18 v) was shown to cultivar Harbin and accession c 21272 and supported by results of two fungal backcrosses. The existence of three unlinked avirulence genes to CI 4922 is suggested (37 a:7 v). The model of interaction between barley resistance genes and avirulence genes with postulated fungal genotypes is proposed.

In this study, we determined the amount of H₂O₂ released by sunflower callus cultures challenged by both crude hyphal wall extracts and culture filtrates of 26 Phomopsis isolates from sunflower of worldwide origin (Argentina, France, Italy, Yugoslavia, Rumania). The amount of H₂O₂ released by callus cultures and the production time-course response, however, did not correlate with both the amount of electrolytes released by sunflower leaf disks treated with crude culture filtrates and the results of pathogenicity tests on sunflower seedlings. Only few isolates induced a time-course response indicative of an oxidative burst. This would suggest that elicitors extracted from hyphal walls are not involved in this host-pathogen recognition system and toxic metabolites produced by Phomopsis in liquid cultures are not pathogenicity factors.

Viruses as phytopathogenes have been discovered at 1892, and 638 plant's viruses have been identified at 1989. Some of its may be epidemic and to cause significant yield losses of cultivated crops. Increasing resistance of the single plant and populations is the necessary condition for the control of viruses spread and damage. Our proposals for the increasing resistance to viruses: For the single plant the soft correction of plant's metabolism with pretreatment of the natural bioantioxidants and immunizators - steroid glycosides. It results in lowering of virus infectivity, degree of plant's affection and increasing of the yield on 11-41% in fact (in ToMV-tomato pathosystem). For the plant's population- increasing to the necessary proportion the lot of tolerant and resistant forms into the plant's assortment; - selection of resistant and tolerant forms from populations have been selected earlier as resistant to other pathogens and obtaining of the basic material collection with complex resistance; - hybridization programs and developing of tolerant and resistant hybrids; - use molecular markers of resistance for the limitation of virus infection backgrounds in the breeding programs.

We determined partial nucleotide sequences of several different field isolates of PMTV with well-characterized biological properties from the Czech Republic and Denmark. Subsequently we were trying to elucidate the correlation between nucleotide sequences of various isolates, their biological properties and geographical origin. From the comparison with other known sequences we can conclude, that PMTV genome is relatively conserved.

In 1998 and 1999 a total of 84 samples of corn, predominantly from localities in southern and central Moravia, were collected either directly from fields (entire ears at harvest maturity) or as grain from merchants. The objectives of the experiments were (a) to determine, on the basis of the results from mycological and toxicological analyses, the basic spectrum of fungal contaminants of corn in the Czech Republic with special reference to the genus Fusarium, and (b) to determine by enzyme immunoassay the presence of major toxic metabolites such as deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZEA), and fumonisins (FUM) in grain samples. From naturally infected corn, representatives of seven fungal genera were isolated under in vitro conditions in both harvest years. Most frequent were species of the genus Fusarium (mean contamination of 44.6%). The next frequent genus was Stemphylium (29.3%). Eight species of Fusarium were found. In both years the most frequent species was Fusarium graminearum (1998 - 42.75%, 1999 - 41.8%), followed by F. culmorum. DON was found in 95.2% of the samples; its content ranged from 25 to 285 µg/kg. The content of T-2 varied more than that of DON, ranging from 12 to 875 µg/kg. Zearalenone content was more varied than that of the trichothecene-type compounds; 17% of the samples did not contain ZEA, the maximum content was 110 µg/kg. No FUM were found in 17% of the samples; in the others, FUM ranged from 12 to nearly 1000 µg/kg. Compared with the other three compounds, fumonisins showed generally the highest levels.

The objective of the study was to identify genes for resistance to powdery mildew in wheat cultivars and land races from Poland, Slovakia and Hungary. The presence and distribution of resistance genes was compared to powdery mildew virulence structure in these countries. The different strategies in breeding for resistance were expressed in a different distribution of resistance genes, especially among Polish and Hungarian cultivars. In 20 of the 29 Hungarian common wheat cultivars the resistance gene Pm8 was found. Of the 32 Polish cultivars investigated, 16 possess a combination of genes Pm2+6. Resistance gene Pm4b did not occur in any Hungarian cultivar tested, and resistance gene pm5 was not detected in any Polish cultivar. Virulence in wheat powdery mildew populations was influenced by differences in distribution of resistance genes in host genotypes. The most significant difference was found between Polish and Hungarian powdery mildew populations. The two populations differed mainly in virulence against Pm2. Resistance gene MlAr was detected in three old Slovak cultivars.

During 1996-2000 the secondary succession on a field left fallow was investigated. The experimental area was divided into a ploughed and an unploughed part. Both parts were divided into 5 × 5 m plots that were either left intact (control), mowed in June or July, or superficially cultivated in June. The position of the plots was identical each year. In successive years total dry matter production decreased in all experimental plots; in unploughed plots more than in ploughed ones. The spread of Cirsium arvense (L.) Scop. was increased by ploughing and superficial cultivation. Ploughing stimulated the spread of perennial dicotyledonous plants more than mowing in June and July. Superficial cultivation increased the spread of perennial dicotyledonous plants in the first years. Later on the proportion of perennial dicotyledonous plants decreased and after 5 years the plots were dominated by Anisantha sterilis (L.) Nevski. The incidence of Elytrigia repens (L.) Desv. was highest in the 5th year on unploughed control plots. The spread of perennial monocotyledonous plants was lowest in ploughed and superficially cultivated plots.

ocids are commonly found to be a persistent pest in structures of grain stores. Grain residues are potential pest reservoirs that serve as sources of grain re-infestation. Weight losses caused by psocids on broken wheat kernels were measured. Average weight loss of grain samples was 9.7% after 3 months of Liposcelis bostrychophila infestation. The weight losses were positively correlated with progeny production.

Results of researches carried out in 2000 and 2001 have demonstrated, that main factors determining yield of winterwheat are: agrotechnical measures, mainly proper choice of field, optimal nitrogen fertilization as well as choice ofcultivar well adapted to local climatic conditions. Chemical protection of winter wheat affects first of all stability ofyield. Regular inspections of fields with special account to present phytosanitary situation, thresholds of noxiousness andexpected development of disease and pest populations should decide on the need of chemical treatments.

In order to investigate cross-protection mechanisms between stresses of different origins, greenhouse experiments were conducted to determine whether resistance levels to the fungal pathogen P. capsici were affected on wounded plants. To this purpose, tomato roots were wounded at 24h-intervals and allowed to age for up to 7 days before inoculation. Data from preliminary experiments indicate first (0-48 h old wounds) an increase in disease severity in wounded as compared to unwounded tomato plants infected with P. capsici. Then, as the wounds age, disease severity decreases to the point that plants wounded 3 days before inoculation are less susceptible than nonwounded plants. Here, with the use of tomato mutant lines, we suggest the involvement of ethylene (C₂H₄) and jasmonates (Ja) in the development of these responses towards P. capsici upon wounding of tomato plants.

The tolerance to or phytotoxicity of selected herbicides and their impact on seed yield was investigated in six grasses grown for seed: Phleum pratense cv. Sobol (a), Festuca rubra cv. Táborská (b), Festuca pratensis cv. Otava (c), Poa pratensis cv. Slezanka (d), Arrhenatherum elatius cv. Medián (e) and Dactylis glomerata cv. Zora (f). All species were tolerant to Grodyl 75 WG (amidosulfuron 75%), (a) and (f) were tolerant to Grodyl plus (amidosulfuron 15 g/kg + isoproturon 600 g/kg) which was phytotoxic to the other grass species; all species were tolerant to Stomp 330 E (pendimethalin 330 g/l); Lintur 70 WG (triasulfuron 4.1% + dicamba 65.9%) was phytotoxic only to (c) while the other species were tolerant to it.

First outbreaks of fire blight were detected in Austria in 1993 and in Hungary in 1995. 137 Erwinia amylovora isolates were compared by PCR-RFLP, sequencing of the repeat region of the PstI fragment of plasmid pEA29, RAPD and AFLP analysis. Differences of repeat numbers in first isolates were observed. Six isolates showed different RAPD profiles. In AFLP analysis, so far, no differences in fragment pattern were determined. Pathogenicity tests with micropropagated apple cultivars revealed differences in plant susceptibility and in virulence of isolates. Responses of Malus tissue were visualized by the use of epifluorescence microscopy through the localization and the production of substances involved in cellular defence mechanisms (e.g. flavonoids, lignin) in various susceptible cultivars. The effect of bacterial strains differing in pathogenicity is shown by cellular peroxidase and flavonoid production.

Leaf spot pathogen is characterized as a highly developed parasite after investigation of development peculiarities of the fungus in pure culture and natural conditions. The degree of correlation depended on the medium. Impact of incubation temperature on Blumeriella jaapii (Rehm) Arx growth was different. Fungi colonies formed more intensively and their diameter increased significantly under higher temperature. Optimal conditions for the disease prevalence are 15-20°C and moisture. Relative humidity and precipitation influenced maturation of ascomycetes and discharge of ascospores (r = +0.89). Microscopic analysis of leaves showed that during winter thaw, when the average temperature is about 0 ± 5°C and relative humidity is higher than 70%, was possible to detect mature ascomycetes and conidia. It is possible to affirm that lower temperature than it was assumed is sufficient for formation of ascomycetes.

The effectiveness of fenarimol and difeconazole, DMIs fungicides, and dodine was tested in two experimental orchards and in greenhouse in two seasons. In 2001 monitoring of resistance to dodine was conducted also in some commercial orchards located in main apple production. In both experimental orchards fenarimol gave significantly poorer control of apple scab than difenoconazole when curative treatments were applied. The same results were obtained in greenhouse tests using for inoculation the suspension of conidia of V. inaequalis from these orchards. In many monitored orchards, in each region, a high level of dodine resistant isolates in population of V. inaequalis (even more than 40%) was noted. Only in six from 65 tested orchards there was less than 1% resistant isolates in population of the fungus.

To search for host proteins involved in systemic spreading of Tomato spotted wilt virus (TSWV), the virus-encoded NSm movement protein has been utilized as a bait in yeast two-hybrid interaction trap assays. J-domain chaperones from different host species and a protein denominated At-4/1 from Arabidopsis thaliana showing homologies to myosins and kinesins were identified as NSm-interacting partners. In this communication we illustrate that following TSWV infection, J-domain proteins accumulated in systemically infected leaves of A. thaliana, whereas At-4/1 was constitutively detected in leaves of A. thaliana and Nicotiana rustica.

It is indispensable to have accurate and speedy method of nematodes detection considering their great deal of malignancy nematodes. For identification of Meloidogyne incognita genetic primers were designed and the procedure was attested by Polymerase Chain Reaction.

Effect of temperature on growth and antagonistic ability of Trichoderma spp. isolated from local strawberry culture and commercial product, against Rhizoctonia solani, strawberry pathogen, was studied in vitro. Trials were carried out twice, at 10, 25 and 30°C. Inhibitor effect was evaluated by radial growth measures of established duals on PDA's dishes, using Royse and Ries formula, to evaluate the percentage inhibition of radial growth. Design of dishes was a randomized complete block, considering 10 replicates. Data were analyzed statistically by two-way analysis of variance. The objective has been to determine the most competitive Trichoderma strain and the best temperature that produce the inhibiting effect on the pathogen growth. Local strain has the best behavior at 10 and 25°C.

The major insect pests on rice in Tanzania are listed and described. They are from five orders (Coleoptera, Diptera, Hemiptera, Lepidoptera and Orthoptera) and are discussed as stem borers, stem and root feeders, and leaf and panicle feeders. This review puts together the hitherto fragmented information available on the distribution, host range, biology/life-cycle and ecology, and the management measures of the insect pests of rice. Areas for future research are also mentioned.

Verticillium wilt causes serious losses in the cultivation of shade trees, especially Norway maple (Acer platanoides L.).In 1993 research was started aiming at the development of Verticillium resistant rootstocks for Norway maple. Efficientmethods to select and screen for resistance in maple were developed, leading to several large-scale selection experimentscarried out in the period 1994-1996. This resulted in a first selection of about 300 plants out of a total of nearly 20 000 seedlingplants. An attempt was made to propagate these plants vegetatively in order to develop small clones for resistancetesting. During this stage of the research many plants were lost because of failure to propagate. After a second screeningfor resistance 35 plants were selected for further examination. Vegetative propagation was continued and from 2000 onthe performance of about 15 clones could be tested on naturally infested fields as well as after inoculation. The resultsof the field test show a clear selection response with disease incidence in plants of the selected clones being 50% lessthan in the seedlings and the randomly chosen clones. Within the group of selected clones there was a substantial variationbetween the clones with some clones having no disease at all whereas in other clones some plants showed serioussymptoms. Results of the field tests will be presented and the possibilities for solving the Verticillium wilt problem inmaple by means of using clonal root-stocks that are resistant to Verticillium wilt will be discussed.

Pythium oligandrum Drechs. belongs to the order Oomycetes. It is parasitic on many fungi from the same or other orders. The antagonism of P. oligandrum is a multifaceted process dependent on the target species involved. P. oligandrum is nonpathogenic on 12 species of crops from six families. It does not attack their tissue but occurs on the root surface, predominantly in the regions of hypocotyl - taproot, together with plant pathogenic fungi. It utilises the root exudates and fungus hyphae on the root surface, including those of the plant pathogens, for its own support. A growth stimulation of plants was observed. P. oligandrum can be utilised for biological control on a wide spectrum of crop plants. Different methods of application have been developed. The effect of a mycoparasite preparation is more preventive.