Mycofungicide: <i>Trichoderma</i>Based Preparation for Foliar Applications

The Trichoderma based emulsifiable mycofungicide for controlling foliar diseases lessened the yield loss to economically acceptable level with significant increase of the quality of product. The amount of phylloplane originated T. harzianum and T. parceramosum strains containing liquid formulation, to be applied as leaf spray, might be reduced in two order of magnitude as compared to the solid preparations to achieve the same effect. Both sensitivity of 13 phytopathogenic fungi to antifungal properties of toxic substances released by 32 Trichoderma strains and their susceptibility to the same were examined during development of new mycofungicide. Both toxin production of Trichodermas and the sensitivity of target fungi varied within large limits, being Pythium irregulare the most, while Phytophthora infestans and Macrophomina phaseolina the less tolerant. The sensitivity responses of fungi to toxins correlated to their susceptibility to antagonists. The spectrum of antagonists of pathogenic fungus or targets of Trichoderma strain proved to be unpredictable. Conidia of Trichoderma strains in liquid paraffin (LP) of pharmaceutical quality (LP PQ) survived over 2 years. However, in commercial LP the shelf life of them significantly decreased in strain dependent manner, and the presence of emulsifiers selectively reduced the survival rate as well. The LP PQ was not phytotoxic in therapeutic doses, but commercial LP proved to be toxic when applied as leaf spray independently on the emulsifiers. Both fungitoxic and phytotoxic contaminants of commercial LP could be eliminated with activated carbon.

Response of <i>Arabidopsis</i>Clones to Toxic Compounds Released by Various <i>Rhizoctonia</i>Species

Response of 3 Arabidopsis clones to 41 strains of eight Rhizoctonia species was studied in model experiments. The seed germination was decelerated in most of the cases, although the inhibitory effect varied within large limits. The pre-emergence damping off and root neck rot leading to damping off were the most frequent symptoms of disease syndrome caused by toxic metabolites. The clone transformed with cDNA clone overexpressing gstf4 gene exhibited significantly improved tolerance as compared to parental one, meanwhile the sensitivity of Dmannose pyrophosphorylase/mannose-1-pyrophosphatase deficient clone dramatically increased. Strains of R. solani of AG-2, AG-4 and AG-7 and Athelia rolfsii produced the most toxic metabolites, however, no strict relationships were revealed between taxonomic position of Rhizoctonia strains and toxicity of their metabolites.

Susceptibility of Wheat Varieties to Soil-Borne <i>Rhizoctonia</i>Infection

Response of 19 wheat varieties cultivated in Hungary varied within large limits to soil borne Rhizoctonia infection. The most frequent symptom, usually leading to damping off was the root neck necrosis. Four significant factors influencing the susceptibility of wheat comprised 71% of total variation but none of them was dominant. The inhibition of development of survivors in Rhizoctonia infested soil correlated with overall susceptibility of variety concerned. The varieties Emese, Kikelet and Palotás are proved to be less susceptible, but none of the varieties could be certified as tolerant. No relationships were revealed between pathogenicity of 26 Rhizoctonia strains studied and their taxonomic position or origin. The anamorph strains of Athelia, Ceratobasidium, Ceratorhiza and Waitea similar to Thanatephorus anamorphs selectively infected the wheat varieties, but the syndromatic pictures were undistinguishable with unarmed eye. R. solani was proved to be more aggressive against germinating wheat than R. cerealis. Nine significant factors influencing the virulence of Rhizoctonia strains comprised 82% of total variation, and six of them influenced exclusively Thanatephorus anamorphs.

Stereospecific Degradation of Diastereomers by Plant Associated Bacteria Influences the Antifungal Performance of Dodemorph

Morpholine fungcides have certain antibacterial side effect, dodemorph being the most active among them. The diequatorial (cis-)?form of dodemorph expressed higher antibacterial activity than the axial-equatorial (trans-)?form, and no synergy in their joint action could be revealed in this respect. Moreover, the partition of diastereomers between cells and medium strictly correlated to their toxicity.?Considerable differences were detected among degradation rates in various bacteria, and the?meso-(RS)-diastereomer was deteriorated more intensively, then the?trans-(SS?and?RR)-forms in?Corynebacterium?betae,?Erwinia uredovora?and?Pseudomonasfluorescens. As a result, the stereospecific degradation of diastereomers changed their ratio in the medium, thus this metabolic step could?influence the antifungal performance of dodemorph based preparations against filamentous fungi. It was demonstrated that due to synergic joint action,?the fungistatic effect of morpholine derivatives noticeably increased against?Botrytis cinerea?by changing the ratio of diastereomers.

Vintage Effect on the Strain Dependent Dynamics of Ethanol Production in Vineries of Tokaj

The dynamics of ethanol production of local strains of three yeast species and their ternary mixtures was examined in two Tokaj vineries. Although, the performance of them diverged significantly in first etaps of vinification—up to the utilization of half of the sugar content of grape juice—the variations vintages per vintages surpassed the strain-dependent alterations. The divergence in the latter aspect diminished during the last etap, and the ethanol concentration in young wines fermented by Saccharomyces cerevisiae, S. uvarum and Starmerella bacillaris (2 local strains of each) and their mixtures did not vary considerably (c.v. 4.2%). The vinification of grape juice performed more rapidly in fermentors inoculated with strains of S. cerevisiae, S. uvarum and St. bacillaris as well as with their mixtures than in spontaneously initiated ones by wild mycoflora in each vintage. The strains responded in different manners to conditions vintage per vintage, however, their ternary mixtures always fermented more intensively the grape juice than the strains alone. The strains affected the dynamics of alcohol production to different extents, but the alterations between them exceeded the variation between the average effects of the species. The circumstances of vinification significantly influenced the subsequent events of fermentation, but the maximum intensity of ethanol production was inversely proportional to the time required to start alcohol production (p > 0.05), similar to that observed in the laboratory under strictly controlled micro-vinification experiments. The maximum intensity of ethanol production (MIE) varied between 0.64 - 2.59 mM ethanol per hour. The coefficients of second-order polynomial equations describing the dynamics of alcohol production in both laboratory micro-scale and medium-scale experiments in cellars revealed similar correlations regarding the interaction of factor groups regulating the process: the constant (time-independent) and secondary (time-dependent) coefficients of these polynomes counteracted to the primary (time dependent) ones strictly in the strain-dependent manner, and the role of these three factors groups varied also in a strain dependent manner during the vinification process independently of the varying circumstances in three vintages.