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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.

Temperature plays a key role in the time needed for development of Tetranychus urticae. It developed fastest at 35°C (6.50 d) and 30°C (6.93 d), while at 15°C it took 16.23 d. The higher the temperature, the faster the development of the mite. As to host plants involved, T. urticae developed fastest on Phaseolus vulgaris (9.42 d), followed by Cucumis sativus (10.26 d) and Capsicum annuum (10.92 d). Fecundity was highest at a temperature of 30°C (89.1 eggs), and lowest at 15°C (58.6 eggs). The fecundity of female mites increased with temperatures up to 30°C, but at 35°C it had decreased (71.08 eggs). The host plant influenced female fecundity to a limited extent; the average on Phaseolus vulgaris was 79.28 eggs, 71.48 on Capsicum annuum and 71.22 on Cucumis sativus.

For the first time in the Czech Republic, bacteria identified as Pseudomonas marginalis, Pectobacterium carotovorum subsp. carotovorum and Pseudomonas putida were isolated from tubers of Zantedeschia spp. with symptoms of tuber soft rot. The symptoms occurred on mother tubers as well as on new daughter tubers of different calla lily hybrids with yellow spathe, calla lily cv. Mango with bright orange spathe and Zantedeschia rehmanii with pink spathe. The percentage of diseased plants of the total plants in the plot was around 10%. When inoculated into potato tuber slices, strains of P. marginalis and P. c. subsp. carotovorum produced soft rot. Pectolytic activity of P. marginalis strains was less intensive than that of the P. c. subsp. carotovorum strain. The results confirm that bacterial soft rot of Zantedeschia spp. may have several causes.

The virulence of 166 Fusarium solani isolates collected in the Czech Republic from infected pea plants was evaluated. Based on the ability to produce phytotoxic naphtarazin (DHF - dihydrofusarubin), only two isolates from this collection (designated FS VG and FS We) corresponded with the characteristics of f.sp. pisi. Suitability and effectiveness of two methods of inoculation based on soaking of seed in the inoculum were evaluated. The possibility to use mixtures of inocula of different species (F. solani f.sp. pisi + F. oxysporum f.sp. pisi races 1 and 2) and of mixtures of two isolates with different virulences was explored. Employing an efficient testing method and the most virulent isolate FS VG, 184 semileafless types of field peas and garden peas were screened to find accessions with a higher level of resistance to F. solani f.sp. pisi.

During 1997-1999 the injury caused by insect herbivors and mortality of plants of field penny-cress (Thlaspi arvense L.) was studied on an early fallow field at Prague-Ruzyně. The highest abundance of the weed (102 plants per m2) was recorded in 1999, the lowest (27 plants/m2) in 1998. Nearly all plants (100% in 1997 and 1998, 94% in 1999) were injured by flea beetles (Phyllotreta spp.). Injury was greatest (> 50%) in younger seedlings. Mortality was low in 1997 (17.1%) and 1999 (15.8%), but high in 1998 (94%) because of concurrent drought. Herbivory and drought may kill a large proportion of seedlings and thus change the composition of the weed community.

Leaves from uncultivated and unsprayed hazelnut shrubs, Corylus avellana, were sampled from June to August 2005 to obtain information on the phytoseiid mite taxocenoses, population density and intraleaf distribution. Six phytoseiid mite species were identified, of which three, Kampimodromus aberrans, Euseius finlandicus and Neoseiulella tiliarum, were more abundant. The eudominant, slowly moving K. aberrans was found on all leaf samples. Phytoseiid population density averaged 3.16 mites per hazelnut leaf. While on most leaves only one phytoseiid species was found, on some there was cohabitation of two (rarely three) species. The three frequent species mostly inhabited the sheltered microhabitat at the veins of leaves of C. avellana.

During 1997-1999, occurrence of hymenopteran parasitoids of cereal aphids was observed in different localities in Slovakia. Altogether, seven species of aphid parasitoids were recorded. The total numbers of particular species over the last three years were as follows: Aphidius uzbekistanicus (160 individuals - 42.4%), Aphidius ervi (83 individuals - 22.0%), Aphidius rhopalosiphi (66 individuals - 17.5%), Ephedrus plagiator (40 individuals - 10.6%), Praon volucre (26 individuals - 6.9%), P. gallicum (1 individual - 0.3%), and Aphidius picipes (1 individual - 0.2%). The abundance of the parasitoids in each year was: 185 individuals (49.1%) in 1999, 122 individuals (32.4%) in 1998, and 70 individuals (18.6%) in 1997.

Otiorhynchus sulcatus is considered as an important pest of strawberry fields and on potted ornamental plants. The efficacy to control this pest by new Polish products containing azadirachtin and the entomopathogenic fungus Beauveria brongniartii were tested. The aim of the laboratory investigation was to assess the influence of different forms of azadirachtin (A and B) and the entomopathogen on mortality and physiological development of the insect. Mortality after treatment ranged between 86-93%. There were significant differences in the mean number of surviving stages of the insect between Beauveria and neem treatments, but the final total mortality was not statistically different. Sensitivity of all developmental stages to the fungus was observed. In the neem treatments the physiological development of larvae was completely stopped. The level of control achieved by Beauveria and neem for use in outdoor containers is acceptable for practical application.

Electron microscopy was used to detect the presence of virus particles or inclusions in growth tips and parenchymatic cells of leaves of plum, apricot and peach trees artificially infected with Plum pox virus (PPV). Typical pinwheels were found in ultrathin sections of leaves of PPV infected plums, apricots and peaches. Filamentous particles or their aggregates approximately 750 nm long were found in ultrathin sections of growth tips of plum, apricot, and peach shoots with a diameter of 0.5 mm. Pinwheels were never present in embryonic cells. No virus particles were found in ultrathin sections of growth tips of PPV infected plum, apricot and peach shoots of 0.2 mm in diameter. Embryonic cells of growth tips up to 0.2 mm in diameter are PPV free. PPV particles are present in growth tips at a distance 0.2-0.5 mm from the top; the virus is probably multiplied in this part of the growth tips.

Transgenic plums, Prunus domestica L. clone C5, were inoculated by bud grafting with Plum pox virus (PPV-Rec, recombinant strain originated from plum), PPV-Rec + Apple chlorotic leafspot virus (ACLSV), PPV-Rec + Prune dwarf virus (PDV), and PPV-Rec + ACLSV + PDV. Non-inoculated transgenic plums served as controls. Plants were grown in an open field for 5 years. They were evaluated by visible symptoms, by DAS-ELISA and RT-PCR. Mild PPV symptoms, diffuse spots or rings appeared two years after inoculation in some leaves of plants artificially inoculated with PPV-Rec, PPV-Rec + ACLSV, PPV-Rec + PDV, and PPV-Rec + ACLSV + PDV. Severe PPV symptoms appeared in leaves of shoots growing from infected buds used for inoculation. During the following three years, further weakening of PPV symptoms was observed in transgenic plants. In 2007, very mild PPV symptoms were found in only a few leaves, and over 60%, resp. 70% of the C5 trees showed no PPV symptoms. The presence of PPV was confirmed by ELISA, ISEM and RT-PCR. No difference in PPV symptoms was observed between PPV-Rec and combinations PPV-Rec + ACLSV, PPV-Rec + PDV, PPV-Rec + ACLSV + PDV. No symptoms of ACLSV appeared in combinations of ACLSV with PPV-Rec and PPV-Rec + PDV during 2004-2007, but the presence of ACLSV in leaves of transgenic plants clone C5 was proved by ELISA and RT-PCR. Neither synergistic nor antagonistic effects of ACLSV on PPV-Rec were observed. No symptoms of PDV appeared in combinations of viruses with PDV during 2004-2007. PDV was not detected by ELISA, and the presence of PDV was uncertain by RT-PCR in most of inoculated trees in 2006 and 2007. The results of RT-PCR will be further confirmed by sequence analysis and discussed. These results suggest a possible antagonistic interaction between PPV-Rec and PDV in plum clone C5.

The frequency of occurrence of four Fusarium spp. on wheat in the Moravia region, Czech Republic, was determined by polymerase chain reaction (PCR). Grain samples were collected during 2003-2006 at grain purchase centres. The dominant species was F. graminearum, which was recorded in all samples of the first 3 years of the study and in 88% of them in 2006. The previously more frequent F. culmorum was detected in 100 % of the samples only in 2005; in the preceding two years the frequency of its detection was lower, 84% and 60%, and in 2006 it was detected in 55% of the samples. Fusarium avenaceum had a very low occurrence in the years 2003-2004, but in 2005 it was recorded in 100% of the samples. In 2006 it was the opposite - total absence of this species. A quite different situation was found in the occurrence of the fourth species - F. poae. In the years 2005 and 2006 it was only detected in 10%, resp. 2% of the samples, compared to markedly higher occurrences in the previous years. A comparison of the current weather development with the long-term mean at the Troubsko locality suggests that years with a relatively long, wet and cold start of the growing season and warmer end of vegetation (late May-July) will favour F. graminearum.

Germination experiments frequently use seeds that had been stored frozen. We investigated whether short, 5 day freezing changes percentage and rate of germination of seeds of dandelion (Taraxacum officinale agg.). Seeds (i) collected at dispersal, (ii) dried at +50°C for 5 days, (iii) frozen at -20°C for 5 days, (iv) dried for 5 days and subsequently frozen for 5 days, and (v) frozen and subsequently dried, were then germinated at +10°C and a long-day photoperiod. None of the temperature pre-treatments affected the proportion of germinating seeds. By contrast, the time to germinate 50% of the seed (germination time) was shortened slightly (0.7 days) but significantly following the freezing treatment, regardless of whether it was applied without, before or after drying of the seed. Cryopreservation is therefore a convenient method of seed storage for comparative studies of seed germination because it causes no change in germination percentage and only a small and systematic change in germination rate.

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.

Fifteen registered winter wheat cultivars were tested for reaction to common bunt in 2-years trials. A mixture of seven Czech proveniences of common bunt was used for inoculation. Cvs Globus and Bill were most resistant in both years. The reaction of these two cultivars to 16 Czech and German samples of common bunt of different proveniences was also tested. On cvs Globus and Bill only one sample in one year caused bunt incidence 29.3% and 19.3%, whereas the incidence caused by other bunt samples was below 10% and 15%, respectively.

Results of scoring the reaction to powdery mildew of 240 winter barley varieties that were gradually included in 392 Czech Official Trials conducted at 21 locations were analysed. The reaction of the varieties was determined on the basis of the level of infection by the disease. Therefore, the data can also be used to assess the disease severity in years and at locations. Several characteristics indicative of disease severity were considered, including the disease severity coefficient (= average infection of susceptible varieties in trials with a high disease severity/the proportion of such trials). The value of the coefficient is inversely proportional to disease severity. The highest powdery mildew severity was found in 1976, and the years 1988, 1990 and 2003 were characterised by high infection of the examined varieties. In contrast, the disease was practically absent in 1979 and 1982, and its severity was also low in 1978, 1981, 1985, 1991 and 1998. Very low disease severity was found for the period 1977-1982 when insufficient disease severity was found on average in 78% of the trials and high disease severity in only 6% of the trials. The highest disease severity was found at locations Trutnov, Horažďovice and Chrastava. The analysis of data from a large number of field trials conducted at various locations for a period of 30 years confirmed that powdery mildew is an important disease of winter barley in the Czech Republic. Known genetic sources of resistance and current methods, such as marker assisted selection, enable breeders to solve this problem.

Rice yellow mottle virus genus sobemovirus (RYMV) was first reported in Kenya in 1966. The disease caused by this virus is fast becoming a major limiting factor in the rice production in Africa and neighbouring islands. It is known to occur in eastern, western and southern African countries and, since very recently, in Central Africa. It is transmitted by insect vectors such as Chaectonema spp., Sesselia pusilla Gerst. and Trichispa sericea Guerin (all Coleoptera) and also by mechanical means. About six strains of the virus now exist. Yield losses caused by the virus range from 20 to 100%. Integrated pest management has been suggested to minimise damage caused by this disease to rice. This paper reviews the characteristics of the virus, symptomatology, host range, distribution, strains, transmission, vector dynamics and virus spread, the economic importance, and management strategies. The need of future research of RYMV is also highlighted.

This study provides new data on Dutch elm disease in the Czech Republic. Ophiostoma novo-ulmi is reported for the first time in the area of the Czech Republic, as well as both subspecies ssp. novo-ulmi (indigenous in the area of the Ukraine and Moldavia), and ssp. Americana indigenous in North America. The majority of the recorded strains belonged to O. n.-u. ssp. novo-ulmi, while O. n.-u. ssp. Americana and hybrids of these two subspecies were found less frequently. On the other hand, Ophiostoma ulmi was not found at all in the investigated samples. Identification on the subspecies level was performed by methods of molecular biology, i.e. PCR and RFLP of gene regions cu and col1.

The toxicity of three concentrations (5%, 10% and 20% w/v) and spraying schedules (2, 4 and 6 weekly applications) of an extract from West African black pepper, Piper guineense, for managing two major post-flowering pests of cowpea, Vigna unguiculata, was investigated in two cropping seasons at the Research Farm of the Institute for Agricultural Research, Ahmadu Bello University, Zaria, Nigeria. The insect pests were the larvae of Maruca vitrata (Lepidoptera: Pyralidae) and the cowpea coreid bug, Clavigralla tomentosicollis (Hemiptera: Coreidae). The higher concentrations (10% and 20% w/v) and more frequent applications (4 and 6/week) significantly (P < 0.05) reduced the numbers of the two insect pests compared to the untreated control in both years. Pod damage was significantly reduced and grain yields consequently increased in treated plots compared with the other extract treatments and the untreated control. West African black pepper extract applied at higher concentrations and more frequently could play an important role in integrated management of pests' infestations on field cowpea managed by limited resource farmers in third world countries.

In the autumn of 2006 and summer 2007 the coreid species Leptoglossus occidentalis Heidemann, 1910 was detected in the Czech Republic for the first time as a new alien insect species. It is native to North America, where it causes important seed losses on coniferous trees, especially pines. From Europe it is known since the end of the last century, when it was introduced to Italy. Its repeated finding could indicate a vital population of this species in the Czech Republic, not only introduced individuals.

The acute and chronic toxicity to honeybees, Apis mellifera of water guttation and dew collected from winter rape plants treated with the insecticide Nurelle D^® (a.i. chlorpyriphos + cypermethrin) was investigated. Caged bees were fed on sugar syrup containing water guttation and dew for 24 h (acute toxicity test) and for 10 days (chronic toxicity test). Bee mortality and food consumption were determined daily. A contact toxicity test was performed within 24 h on bees kept in Petri dishes (10 bees per dish) lined with filter paper saturated with the test solution. The acute Nurelle D^® contact and oral toxicity tests showed that the mortality of bees treated with water guttation and dew collected from the treated plants did not exceed 10%. A chronic toxicity test showed that adding contaminated water guttation and dew to the syrup caused an insignificant increase in bee mortality and reduced the syrup consumption significantly. The chlorpyriphos residue found in contaminated water guttation and dew were below the limit of detection (0.8 µg/kg) and the cypermethrin residue was below the detection levels.

Greenhouse trials were conducted during 2005 to investigate the effect of six soil applied herbicides on common cocklebur (Xanthium strumarium L.) sowed at a depth of 4 cm and 7 cm, and determine the potential injury to maize by the herbicides and the influence of sowing depths. The efficacy of all herbicides was high, regardless of sowing depth and, generally, the coefficient of efficacy ranged from 86.3% to 100.0%. Most of the herbicides had no significant phytotoxic effect on maize plant density/container, height and fresh weight of maize. Exceptions were Atranex-90WDG and Cyatral-SCZ, which caused serious injury to maize (33% and 37%, respectively) if seeded at a depth of 7 cm, and significantly reduced height and fresh weight of the plants.

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.

Cultivars, homozygous sources and lines of pea (Pisum sativum L.) resistant to Erysiphe pisi had recently been attacked by another powdery mildew species, Erysiphe baeumleri, in the field and in glasshouse conditions. Inoculation with E. baeumleri was carried out in the glasshouse to evaluate the level of resistance of 16 pea genotypes. Susceptible pea lines produced abundant conidia and cleistocarps on petioles and leaves. Only the genotype Tudor (Cebeco 4119) was found to be completely resistant to E. baeumleri. Nineteen pea genotypes (with gene er-1) were tested to natural infection by E. baeumleri in field screening trials. Only few of them demonstrated a high level of resistance (Fallon, AC Melfort and Joel). Consort R, SGL 2024, SGL 1977 and Franklin were very susceptible to E. baeumleri. Cleistocarps with 1-4× dichotomously branching apices of appendages were formed only on susceptible and very susceptible plants of genotypes SGL 444/2185, Consort R, SGL 2024, SGL 1977, LU 390-R2, Lifter, Highlight, Cebeco 1171 and Carneval R in the field and glasshouse. Susceptible control genotypes without gene er-1 (Komet, Adept and Gotik) were attacked in the trials by E. pisi only.

In 1995-1997, the population dynamics of the flea beetles Chaetocnema tibialis and Phyllotreta vittula, associated with Amaranthus retroflexus (wild species) and Amaranthus caudatus (cultivated species), were studied at the locality Nitra-Malanta (48°19'N, 18°09'E) in south-western Slovakia. On both plant species, the number of C. tibialis adults was usually very low until the beginning of July. During July the number of C. tibialis increased, but sooner on cultivated amaranth. An increased number of C. tibialis adults was observed on both amaranth species until the middle of September. The results showed that amaranth plants are a very important reservoir of C. tibialis during summer. P. vittula was a common flea beetle on amaranth during the whole summer, but its numbers never exceeded more than 10 adults per 25 plants. Low temperatures in winter had a negative effect on populations of C. tibialis on both amaranth species and also on populations of P. vittula on A. retroflexus. The lower the precipitation was in July, the higher were the populations of C. tibialis on both amaranth species and the populations of P. vittula on A. retroflexus.

Bunts (caused by Tilletia caries and T. controversa) belong to very important diseases of winter wheat because contaminated commodities (seeds, foods and feeds) affect the marketability of the crop on both domestic and export markets. They can be relatively easily controlled by chemical seed treatments. Due to the availability of effective chemical control, the reaction of wheat cultivars to bunts has so far not been an important trait for plant breeders in some areas of the world. However, if synthetic chemicals are not allowed, like in organic farming, untreated seed may quickly lead to a build-up of bunt to levels that render the crop unmarketable. The use of wheat cultivars partially or fully resistant to bunts could greatly contribute to ease the bunt problem. The reaction of winter wheat cultivars was evaluated in field tests. Seeds of winter wheat were inoculated with teliospores of T. caries. The reaction to T. controversa was studied under heavy natural infestation with spores in the soil. With T. caries, the heaviest infection was found in cvs Drifter and Ebi, while cvs Nela, Brea and Samanta had the lowest. The average level of infection with T. controversa was higher than that of T. caries. The cvs Niagara, Brea and Versailles had significantly lower numbers of bunt ears of T. controversa in 2002. The incidence of both bunts in grain samples that had not been cleaned and sorted after harvest was monitored for 4 years. A total of 1 058 samples collected from various locations in the Czech Republic were analysed for the presence of bunt spores and the species determined. The investigation demonstrated a rather widespread occurrence of bunts across the Czech Republic, with T. controversa being more frequent.

The extracts of pods of West African black pepper, Piper guineense, at 5, 10 and 20% (w/v), were applied at two, four and six weekly schedules to control the legume flower bud thrips, Megalurothrips sjostedti on flowers of cowpea, Vigna unguiculata. The trials were conducted for 2 years under rain fed conditions in the northern Guinea savanna region of Nigeria. The results showed that the M. sjostedti population was significantly controlled on treated plots compared with the untreated check in both years. The extracts at the 20 and 10% rates and with six or four weekly applications significantly (P < 0.05) reduced thrips pressure on cowpea flowers, were better than the 5% extract at all spraying schedules, and had the same efficacy as the synthetic insecticide treatment. Pod density per plant was significantly higher (P < 0.05) on plots treated with the 20% extract at six or four weekly applications compared to other extract rates and was similar to that of the synthetic insecticide treatment. Thus, the extracts could be a good alternative to the synthetic insecticides on organically managed farms as well as on farms of limited resource farmers in the tropics and subtropics.