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The article deals with issues of non-market forest services. There is a persistent issue complicating the quantification of adequate subsidy to forest owners - non-existence of market with such forest services. Forest services financing can be made objective by implementation of the following steps: 1. Earmarking of non-market forest services that are becoming market subjects gradually. 2. Earmarking of non-market forest services that create a secondary product of wood production function. 3. Quantification of demand for services. 4. Quantification of costs necessary to cover the demand for those forest services. 5. Quantification of losses caused to forest owners by restricting their economic activities.

The influence of tree age, explant source and genotype on micropropagation of mature trees of Sorbus aucuparia has been investigated. Experiments demonstrated the feasibility to use juvenile parts of mature trees for in vitro propagation of selected genotypes. Explants from lower branches and from epicormic shoots of mature trees exhibited high multiplication coefficients of microshoots cultured on modified MS agar nutrient medium supplemented with cytokinin (BA, TDZ) and auxin (IBA). Microshoots produced from juvenile parts of mature trees exhibited good rooting response and produced plants were well adapted to grow in forest soils. The survival of micropropagated trees planted in experimental plots was high and losses during winter were low. Height and diameter increments of micropropagated trees originated from juvenile parts of mature trees were considerable and their dimensions after five years of growth were comparable with the dimensions of trees originated from seeds.

The reverse transcription polymerace chain reaction (RT-PCR) assay was successfully used for the detection of Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) in four apple cultivars of a 25 years old orchard. These two main pome fruit viruses were detected frequently in all tested apple cultivars. ASGV and ASPV occurred in as many as 16 trees (in the cultivar Spartan) and 13 trees (in the cultivar Idared) out of 20 tested trees, respectively. Mixed infection by ASGV and ASPV was found in all tested cultivars (as many as 9 out of 20 tested trees of the cultivar Spartan).

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.

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 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.

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.

In late August of 2001 a population of Metcalfa pruinosa (Say, 1830) consisting of several dozens of adults and larvae was observed in a nursery of ornamentals at Brno-Bystrc. The species occurred mostly on young twigs of cultivars of Thuja occidentalis L., Juniperus communis L. and Sorbus aucuparia L. but also Lilium spp. and singly on other various wood and herbal ornamental plants. The damage was rather of an aesthetic kind: young twigs were covered by 5-10 cm long spots of waxy fluff produced by the larvae. The pest is native to North America and was introduced in the late 1970's to Italy, from where it spread to southern France, Slovenia and southern Austria. The Brno population might have been imported, in the egg stage, on ornamental shrubs from Italy. The polyphagous pest is very common in Southern Europe, causing damage especially on fruit trees by the secretion of honeydew that, being colonised by Capnodiaceae moulds, inhibits the transpiration. The species could stay permanently in theCzechRepublic or could be repeatedly imported again.

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.

The general outcomes of long-term trajectories of coevolutionary interactions between specific hosts and pathogens areset by the interaction of their life histories. However, within those outcomes the speed of co-evolutionary responses andthe extent of their expression in the resistance/virulence structure of wild plant and pathogen populations respectively,are highly variable characters changing from place-to-place and time-to-time as a result of the interaction of host andpathogen with the physical environment. As a consequence, understanding of the role of diseases in the evolution of theirhosts requires approaches that simultaneously deal with host and pathogen structures over multiple populations within ametapopulation framework.

Dominant resistance genes identified in Brassica napus lines are effective against some, but not all, Turnip mosaic virus(TuMV) isolates. An infectious clone of an isolate (UK 1) was used as the basis of chimeric virus constructions usingresistance-breaking mutants and other isolates to identify the virulence determinants for three dominant resistance genes.For the resistance gene TuRB01, the presence of either of two mutations affecting the cylindrical inclusion (CI) proteinconverted the avirulent UK 1 to a virulent isolate. Acquisition of such mutations had a slight cost to viral fitness inplants lacking the resistance gene. A similar strategy is being used to identify the virulence determinants for two moreresistance genes present in another B. napus line.

The presence of protein in the culture medium induced secretion of proteases in the studied filamentous fungi species. Comparative analysis of extracellular proteases expressed in vivo by saprotrophic (Trichoderma harzianum, Penicillium terlikowskii) and pathogenic (Alternaria alternata, Botrytis cinerea, Ulocladium botrytis) filamentous fungi species has been carried out. All isolated enzymes were classified as serine proteases on the basis of inhibitor analysis data. According to substrate specificity and the effect of some inhibitors it is proposed that enzymes from T. harzianum and P. terlikowskii are subtilisin-like proteases and enzymes from A. alternata, B. cinerea, U. botrytis are trypsin-like proteases. This fact is, apparently, one of the main characteristic properties of saprophytic and phytopathogenic fungi species. Participation of extracellular fungal proteases in pathogenesis is discussed.

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 the framework of the study of the mode of action of biocontrol agents (BCAs) it is important to know if BCAs areantibiotic-producers. Epicoccum nigrum 282 and Candida sake CPA-1 are BCAs effective against post-harvest pathogensof stone and pome fruits. The antibiotics produced by these BCAs and the relationship to biocontrol were studied.Production of antibiotics by E. nigrum in in vitro cultures began at 5 days of incubation being maximal at different timesdepending on media used. However, no antibiotic was detected when E. nigrum was grown in a solid state-fermentationsystem or in peaches. In the case of C. sake, no antibiotic was detected either in vitro, in liquid fermentation culturesof the yeast, or in apples.

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.

A rapid, easy to handling and sensitive RNA preparation procedure, RNA release protocol was described here for the detection of Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) by RT-PCR. Comparing total RNA extraction protocol, RNA release protocol give raised similar rate of ASPV and ASGV detection within the field-grown apple cultivars. Among sampling plant tissues, the bud leaf and leaf (during blossom) were showed efficient tissues for the routine detection, regardless the using RNA preparation procedures.

Fourteen Potato virus Y (PVY) isolates were characterized. They represented PVYN strain only. However, application of serological and molecular genetic methods led to a more complicated characterization. For example, five isolates induced necrotic symptoms on tobacco plants typical of PVY^N, despite reacting as PVY^O serologically. Moreover, the PVY isolates were not identical according to molecular genetic properties. Typical PVY^NTN PCR products were observed for 11 isolates, but four of them (Hr220-5, Hr387-7, Nord 242 and Syn1Scot) did not produce potato tuber necrotic symptoms in infected cultivars. An immunocapture RT-PCR probing was developed using a set of 24 primer pairs derived from eight regions of the PVY genome. Using this method, five out of seven PVY^NTN isolates including the Czech standard PVY^NTN from the potato cv. Nicola were found to be identical. However, two PVY^NTN isolates and all the other probed PVY samples showed unique patterns, suggesting specific differences at the nucleotide level. This method enabled specific identification of individual isolates variability even within different PVY strains.

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).

The role of reactive oxygen intermediate (ROI) accumulation in resistance and susceptibility of plants to parasitic fungi is still little understood. We examined the spatial and temporal occurrence of different ROIs in barley after inoculation with the biotrophic fungus Blumeria graminis f.sp. hordei (Bgh, barley powdery mildew fungus). Using histochemical analyses, we collected correlative data indicating that H₂O₂ and O₂^*- play different roles in background penetration resistance to Bgh. To study the role of O₂^*- in detail, we isolated barley cDNAs encoding a NADPH oxidase GP91PHOX homologue and a RACB homologue, which may be involved in NADPH oxidase activation. Interestingly, transient silencing of RACB or GP91PHOX via sequence-specific RNA interference enhanced penetration resistance of barley to Bgh. Together, data reveal rather a negative than a positive role of superoxide generation in background resistance of barley to Bgh.

Small G-proteins (RAC and RHO) are known to be involved in regulation of superoxide (O₂^*-) production and the assembly of actin fibres. These processes are known to be crucial for accessibility and inaccessibility of barley cells to the biotrophic fungus Blumeria graminis f.sp. hordei (Bgh). Using a candidate RT-PCR approach six Rac-related cDNA-clones were isolated from barley. The transient knock-down of RacB led to a remarkably lower penetration efficiency of Bgh into susceptible barley lines (Mlo/Ror1). Surprisingly the inhibition of RacB expression had no effect in the double mutant line A89 (mlo5/ror1). This led us to the assumption that the RacB-dsRNA effect is dependent on functional ROR1 (such as mlo5-mediated resistance). Vice versa, overexpression of constitutive active RACB-V15 in the susceptible line Pallas resulted in hypersusceptibility to Bgh. Thus, we conclude that RACB is a signal transduction protein functional in the accessibility of epidermal barley cells to Bgh.

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.

Suppression subtractive hybridization (SSH) was carried out to detect genes differentially expressed in plants expressing resistance to systemic infection with Potato virus A (PVA), genus Potyvirus. Differential screening has up to now revealed 19 putative differentially expressed genes. Nothern blot hybridization has confirmed the differential expression of seven genes. Three of them were only induced by the virus, but four genes were also wound-induced.

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.

Postharvest biocontrol activity of CaC_l2 and four yeasts against Penicillium digitatum was tested on Tarocco oranges. All tested organisms (Pichia anomala J121, Pichia guilliermondii NRRL Y18314, Debaryomyces hansenii DBVPG 4025 and Saccharomyces cerevisiae P1.6) significantly reduced mould incidence and severity. Application of CaCl₂ enhanced biocontrol efficacy of P. guilliermondii and S. cerevisiae, while it did not significantly affect biocontrol of P. anomala and D. hansenii.

Chamaecyparis lawsoniana is often attacked by other pathogens (from genera: Phytophthora, Pythium, Fusarium, Rhizoctonia) both when the quicksets are taken root and later, when the young plants are planted. The aim of the study was to determine an effect of saprobiotic fungi isolated from soil with quicksets Chamaecyparis lawsoniana on the growth of Phytophthora cinnamomi and Rhizoctonia solani. In our experiment, method series biotic was used (MAŃKA 1974). This method allowed to determine index of impendence for plants by Phytophthora cinnamomi and Rhizoctonia solani with the help of summary biotic effect. The results of observation on the biotic interaction of saprobiotic fungi isolated from soil with quicksets Chamaecyparis lawsoniana, analysed as biotic series and Phytophthora cinnamomi and Rhizoctonia solani showed, that this of fungal community did not limited growth of these pathogens. Summary biotic effects were negative. Environment of saprobiotic fungi more promoted growth of Rhizoctonia solani than Phytophthora cinnamomi. It means, that in the soil under Chamaecyparis lawsoniana crop, Rhizoctonia solani could have a better of conditions for growth than Phytophthora cinnamomi.

The trials were carried out over the period 1999-2000 with a view to testing the efficacy of reduced doses of triazole fungicides on winter wheat cv. Zentos. Septoria diseases (Septoria spp.) occurred on winter wheat annually. Full and reduced dosages of fungicides were highly effective against Septoria leaf blotch at an early milk stage, especially on flag leaf. Later the efficacy of reduced dosages of the fungicides was lower, than that of full doses. Due to full dosage of fungicides we obtained a sufficient yield increase annually. The yield increase through the use of 3/4 reduced doses was lower. But yield increase through reduced dosage to 1/2 was low and insufficient.

Verticillium wilt is of increasing significance in European agriculture, especially in tree hosts such as olive and stone fruits, and in shade tree nurseries. In the period 1997-1998 eight European research groups participated in an EU-funded Concerted Action on this disease. Main results were the publication of "A Compendium on Verticillium wilts in tree species" (HIEMSTRA & HARRIS 1998) and an RTD-proposal submitted for financing to the 5th EU Framework Programme. This proposal was approved by the European Commission and the research started in March 2000. Ten research groups participate in a project that aims to provide essential elements for an efficient and environmentally sound management of Verticillium wilt in trees. The research concentrates on tree key areas: (1) pathogen variability, (2) host resistance, and (3) detection and risk assessment. In addition the project aims at harmonising methods, exchange of experience and continuation of the successful co-operation developed during the previous Concerted Action. The specific achievements of the project include information on genetic variation within the pathogen and on distribution and virulence of its subspecific groups; standardised methods to select for host resistance; resistant selections of olive and maple; molecular methods to detect the pathogen in soil and plants; and improved risk assessment procedures. Details on aims, methods and participating groups will be presented.

A pot experiment was conducted in order to examine the influence of soil contamination with diesel oil at 0.0, 2.4, 4.8 and 7.2 ml/kg on the activity of dehydrogenases, urease, acid phosphatase and alkaline phosphatase. The results indicated that diesel oil contamination of soil strongly inhibited the activity of dehydrogenases and soil urease, but had only a slight effect on the activity of acid phosphatase and alkaline phosphatase. The negative influence of diesel oil on the activity of dehydrogenases and urease was attenuated by soil inoculation with Streptomyces intermedius spores. The potential biochemical index of soil fertility computed from the soil enzymatic activity and carbon content was negatively correlated with diesel oil contamination and positively correlated with crop yield. Biochemical properties of soil were improved by oat cultivation.

Dual inoculation of peat based horticulture substrate with a mixture of four species of arbuscular mycorrhizal fungi and fungal biocontrol agent Trichoderma harzianum showed a significant positive effect on the growth and flowering of cyclamen plants. Inoculation substantially decreased plant mortality caused by spontaneous infection by the fungal pathogen Cryptocline cyclaminis. Plant mortality was also reduced by separate inoculation with arbuscular mycorrhizal fungi. Both separately inoculated agents positively affected the plant growth, although to a lesser extent. Very few significant effects of inoculation were observed on the growth of poinsettia plants cultivated from cuttings. Use of arbuscular mycorrhizal fungi together with the introduction of Trichoderma for inoculation of horticultural substrates is suggested to alleviate the inevitable effects of various stresses during the cultivation of horticultural crops.

The effect of Al stress on peroxidase activity and peroxidase isozymes was studied in roots of two barley cultivars with contrasting sensitivity to Al. Al treatment induced a tremendous enhancement of guaiacol peroxidase activity especially in roots of Al-sensitive barley cv. Alfor. After 48 h of Al treatment activity of peroxidase in roots of cv. Alfor was up to 5.5 times higher than the control roots. In contrast, activity of peroxidase in the roots of Al-resistant cv. Bavaria was about one half than that in roots of Al-sensitive Alfor. SDS-PAGE analysis revealed that at least five peroxidase isozymes are activated by Al treatment. Using IEF we determined that three of Al-induced peroxidase isozymes are cationic with pI about 8.2, 8.4 and 8.6, while two other are anionic isoperoxidases with pI about 4.0 and 4.5. Al induced increase in the activity of root peroxidases correlated with the extent of Al induced root growth inhibition. The inhibition of root growth in Al-sensitive Alfor represented 44% but in Al-resistant Bavaria only 21% in comparison with control plants. Higher peroxidase activity, as well, as higher inhibition of root growth in Al-sensitive Alfor suggest that enhanced oxidative stress generated by Al treatment is significantly more stressful in Alfor than in the Al-resistant Bavaria.