Search Results (5)

Fusarium species are agriculturally important fungi with a broad host range and can be found as endophytic, pathogenic, or opportunistic parasites in many crop plants. This study aimed to identify Fusarium species in bare-rooted, dormant plants in Turkish grapevine nurseries using molecular identification methods and assess their pathogenicity. Asymptomatic dormant plants were sampled from grapevine nurseries (43) in different regions of the country, and fungi were isolated from plant roots and internal basal tissues. The Fusarium strains were identified by performing gene sequencing (TEF1-α, RPB2) and phylogenetic analyses. Pathogenicity tests were carried out by inoculating mycelial agar pieces of strains onto the stem or conidial suspensions into the rhizosphere of vines (1103 Paulsen rootstock). Laboratory tests revealed that Fusarium species were highly prevalent in Turkish grapevine nurseries (41 out of 43). Gene sequencing and phylogenetic analyses unraveled that 12 Fusarium species (F. annulatum, F. brachygibbosum, F. clavum, F. curvatum, F. falciforme, F. fredkrugeri, F. glycines, F. nanum, F. nematophilum, F. nirenbergiae, F. solani, and Fusarium spp.) existed in the ready-to-sale plants. Some of these species (F. annulatum, F. curvatum and F. nirenbergiae) consistently caused wood necrosis of seedling stems, rotting of the basal zone and roots, and reduced root biomass. Although the other nine species also caused some root rot and root reduction, their virulence was not as severe as the pathogenic ones, and they were considered opportunistic parasites or endophytic species. This study suggests that Fusarium species might play an important role in root-basal rot, wood canker symptoms, and young vine decline in Turkish grapevine nurseries and that these species need to be considered for healthy seedling production. Full article

With natural rainfall and surface water availability becoming scarce, prolonged droughts are expected to become more frequent, thereby creating issues for agriculture. In viticulture, a lack of rainfall is often supplemented with irrigation during the growing season and/or dormancy. However, with surface and groundwater resources declining in addition to current changes in rainfall patterns, it is unlikely that supplemental irrigation will continue to be an available tool for most growers. As such, this study aims to evaluate the effect of dry farming and supplemental irrigation during the growing season on vine performance and fruit composition as a function of vine age in Zinfandel grapevines. A historically dry-farmed vineyard block with interplanted vines of varying ages was evaluated during the 2021 growing season. Treatments included young vines (5–12 years old), control vines (2:1 ratio of old to young vines representative of the block), and old vines (40–60 years old); each age designation included irrigated and dry-farmed vines. Based on age-specific ET_c and to replenish 95% of crop evapotranspiration (ET_c), irrigation was manually applied to the irrigated treatment vines at véraison and véraison + 4 weeks. Results indicated no significant changes in phenological progression, leaf senescence, or physical berry analysis when irrigation was added to dry-farmed vines, as most differences were driven by vine age in most parameters measured. Irrigated vines were slightly more advanced in phenological growth and senescence progression compared to dry-farmed vines. Results suggest that the practice of applying supplemental irrigation during the growing season, provided winter rainfall or additional winter irrigation is sufficient, does not have significant impacts on vine performance. Thus, dry farming during the growing season is a reasonable alternative practice in Zinfandel, even in periods of drought. Full article

Young vine decline (YVD) is a grapevine trunk disease (GTD) which results in stunted and delayed growth, reduced yield, root necrosis and eventually death of young vines. Given losses associated with root trunk disease, and increasing limits on chemical fungicides, there is a need for sustainable approaches to combat disease; (1) Cover cropping is a commonly used practice in agricultural systems and has potential to reduce disease in vineyards but there is a risk that cover crop species may act as a host for grapevine pathogens, increasing the risk of infection; (2) We tested 25 plant species commonly used in cover crops to assess their potential to act as a host for a Ilyonectria liriodendri, which is a causal agent of young vine decline. We inoculated greenhouse pots with a pathogeninc strain of Ilyonectria and assayed the roots for the presence of the pathogen; (3) Of the 25 cover crops tested, many of the species showed increased root abundance of Ilyonectria, compared to background levels. In particular phacelia (Phacelia tanacetifolia) and buckwheat (Fagopyrum esculentum) showed very high levels of root colonization. (4) This is the first study to our knowledge that highlights the potential of cover crops to soil borne fungal pathogens. Full article

Wine grape production is an important economic asset in many nations; however, a significant proportion of vines succumb to grapevine trunk pathogens, reducing yields and causing economic losses. Cover crops, plants that are grown in addition to main crops in order to maintain and enhance soil composition, may also serve as a line of defense against these fungal pathogens by producing volatile root exudates and/or harboring suppressive microbes. We tested whether cover crop diversity reduced disease symptoms and pathogen abundance. In two greenhouse experiments, we inoculated soil with a 10⁶ conidia suspension of Ilyonectria liriodendri, a pathogenic fungus, then conditioned soil with cover crops for several months to investigate changes in pathogen abundance and fungal communities. After removal of cover crops, Chardonnay cuttings were grown in the same soil to assess disease symptoms. When grown alone, white mustard was the only cover crop associated with reductions in necrotic root damage and abundance of Ilyonectria. The suppressive effects of white mustard largely disappeared when paired with other cover crops. In this study, plant identity was more important than diversity when controlling for fungal pathogens in vineyards. This research aligns with other literature describing the suppressive potential of white mustard in vineyards. Full article

Up to 60 species of fungi in the Botryosphaeriaceae family, genera Cadophora, Cryptovalsa, Cylindrocarpon, Diatrype, Diatrypella, Eutypa, Eutypella, Fomitiporella, Fomitiporia, Inocutis, Phaeoacremonium and Phaeomoniella have been isolated from decline-affected grapevines all around the World. The main grapevine trunk diseases of mature vines are Eutypa dieback, the esca complex and cankers caused by the Botryospheriaceae, while in young vines the main diseases are Petri and black foot diseases. To understand the mechanism of these decline-associated diseases and the symptoms associated with them, the toxins produced by the pathogens involved in these diseases were isolated and characterised chemically and biologically. So far the toxins of only a small number of these decline fungi have been studied. This paper presents an overview of the toxins produced by the most serious of these vine wood pathogens: Eutypa lata, Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and some taxa in the Botryosphaeriaceae family, and examines how these toxins produce decline symptoms. The chemical structure of these metabolites and in some cases their vivotoxin nature are also discussed. Full article