1,720,971 research outputs found
FIELD INVESTIGATION ON GARLIC DRY ROT
No full textFusarium proliferatum was signalled worldwide since 2002 as the main causal agent of garlic dry rot. According to literature, other Fusarium spp and nematodes (Ditylenchus dipsaci) could contribute to the disease. Moreover, white varieties are reported as more susceptible compared to red ones. Dry rot is considered a postharvest disease, but relevant incidence of symptomatic bulbs at harvest were also reported. The aim of this study was to investigate infection time and agent involved in garlic dry rot from field to table. Field sampling was organised in Piacenza province (north Italy), area of production of white garlic (PGI). Six field units were selected for sampling, 3 of them with an history of relevant dry rot. Soil was sampled before sowing. Garlic plants were collected in three growth stages: BBCH 15 (5th leaf clearly visible), BBCH 45 (50% of the expected bulb diameter reached), BBCH 49 (Leaves dead, bulb top dry; growth complete). With soil, serial dilutions and colony forming units count (CFU) were performed so as nematode counting. Direct isolation from symptomatic and asymptomatic plants was managed, so as the identification at species level for a selected set of fungal strains. PCR was applied to confirm fungi and nematode identification. Ditylenchus dipsaci was not detected in soil in autumn. Regarding fungi, the largely dominant species were F.proliferatum and F.oxysporum, isolated since BBCH 15, increasing in incidence from early growth stages to harvest. F. proliferatum seems confirmed as the candidate most relevant causal agent of dry rot, infecting bulbs early in field
Efficacia di fungicidi contro tracheofusariosi e marciumi
No full textIn a temperature controlled glasshouse, seeds of tomato varieties not resistant to tracheo-fusarium diseases and rots were sown in soil inoculated with 3 strains of Fusarium oxysporum, F. solani, Pythium aphanidermatum, Pyrenochaeta lycopersici and Phytophthora nicotianae. In a 2nd experiment, seedlings were transplanted into similarly inoculated soil. Immediately after sowing/transplanting propamocarb 530 g/L +or- fosetyl 310 g/L at 4 or 3 mL/L was applied evenly to the soil surface. Damage from all the fungi except F. oxysporum f. sp. radici was insignificant in the sown tomatoes treated with propamocarb + fosetyl, while in the transplanted tomatoes, this treatment was effective except against F. solani and P. lycopersici
Fungal growth and ergosterol content in tomato fruits infected by fungi
No full textTomato fruits, cv. Red river, were artificially inoculated under controllod consitions with the aim of testing in vitro the invasive ability of several fungal species and their effect on microbiological quality. Seven species most frequently associated with spoiled tomatoes were used: Alternaria alternata, Botrytis cinerea, Fusarium oxysporum, Geotrichum candidum, Phoma lycopersici, Rhizoctonia solani and Rhizopus nigricans. Fungal effect was checked at days 1, 2, 4 and 8 after inoculation using three methods: volume of spoiled tomato, Howard Mold Count and the anlytical determination of ergosterol. The results showed significant differences in the parameters measured in relation to the fungi considered, the time of incubation and their interaction. A significant correlation was found between the quality parameters measured with the three evaluation methods but, with a percentage of variation explained by the regression of about 50%. This implies that the relationship between qualitative parameters can be computed, but with a high level of uncertainty (a wide confidence interval). Therefore, it seems only theoretically possible to specify an "alert" value with this procedure
In vitro efficacy tests against Fusarium spp. causing garlic dry rot
No full textGarlic is cultivated worldwide and, according to FAOSTAT, in 2016 1.5 million hectares were destined to this culture. Starting from 2002, Fusarium proliferatum was signalled as the main causal agent of garlic dry rot during storage, but with infections starting during the growing season. Seed sanitation seems crucial to prevent pathogen spread. In the context of preparing guidelines for farmers to prevent/control dry rot in field and during storage, this study was designed. Fusarium proliferatum (MPVPG29) recovered from garlic during the 2017 growing season was used in in vitro trials. Six fungicides, all including triazoles, alone or in mixture, and 4 competitor/antagonist biocontrol agents (BCA; Trichoderma gamsii, Fusarium oxysporum IF23, Bacillus subtilis, Streptomyces griseoviridis K61) were considered. Spiked media for chemicals (4 concentrations (1-1000 ppm) and dual cultures for BCAs were used. Inoculated dishes were incubated at 3 temperatures (10-15-25° C) and the percentage of growth inhibition was recorded after 7-14-21 days. All chemical products were able to stop fungal growth at 100 ppm concentrations and Procloraz+Propiconazole showed a 94% reduction followed by Tebuconazole (57% reduction) even at 1 ppm. Regarding BCAs, T. gamsii was the most effective in reducing F. proliferatum growth (mean reduction=84%), followed by S. griseoviridis (mean reduction=60%). Results are very promising and a field trial is ongoing to verify the performances of BCAs in garlic crops
Advances in understanding stilbene (resveratrol, ε-viniferin) -grapevine relationships
No full textThe paper reviews previous and not yet published results on some aspects of stilbene phytoalexin (resveratrol, ɛ-viniferin and pterostilbene) physiology in grapevine, obtained by the Viticulture Institute of the Catholic University at Piacenza. The effect of mineral nutrition on induced resveratrol and ɛ-viniferin synthesis has been investigated emphasizing the role of nitrogen, wich decreases stilbene leaf levels, and potassium, which increases them. Time course of stilbene accumulation in leaves and berries of different genotypes artificially infected with Botrytis cinerea, is reported.
The paper describes also an attempt to get immunization against downy mildew, by spraying plants with an abiotic elicitor (mucic acid). Constitutive resveratrol contents of bunch stems and roots are described, as well as the possible role of cluster stems as resveratrol source in wine
Components of rate-reducing resistance to Cercospora leaf spot in sugar beet: conidiation length, spore yield
No full textComponents of rate-reducing resistance to Cercospora leaf spot in sugar beet: incubation length, infection efficiency, lesion size
No full textDiaporthe spp. Is Confirmed as the Main Fungus Associated with Defective Turkish Hazelnuts
No full textThe aim of this study was to identify the fungi associated with Turkish hazelnuts and verify and confirm the role of Diaporthe in causing kernel defects. Hazelnuts were sampled from ten hazelnut orchards in seven Turkish provinces (Samsun, Ordu, Girensun, Trabzon, Sakarya, Düzce, and Zonguldak) during the early and full ripening stages in 2018, 2019, and 2020. Fungal isolation and identification at the genus level were performed on healthy hazelnut kernels and those with visible or hidden defects. Several fungal genera were isolated; those with a mean incidence greater than 10% were Aspergillus, Botryosphaeria, Diaporthe, Fusarium, and Penicillium. The incidence of Diaporthe spp. was higher in the full ripening stage than in the early ripening stage; it was also higher in kernels with defects than in healthy kernels. A similar pattern was observed for Botryosphaeria, but the opposite pattern was observed for Aspergillus. Diaporthe positively correlated with both hidden (ρ=0.80) and visible defects (ρ=0.77) confirming its key role in causing hazelnut defects. The role of Botryosphaeria appears limited to hidden defects; however, additional work is needed to substantiate this last finding. There is also a need to clarify the eventual interaction of Diaporthe with Aspergillus. The low incidence of defective hazelnuts among the three years of sampling precluded the role of meteorological factors on the incidence of hazelnut defects from being elucidated
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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