Evaluation of the grapevine nursery propagation process as a source of Phaeoacremonium spp. and Phaeomoniella chlamydospora and occurrence of trunk disease pathogens in rootstock mother vines in Spain

Abstract

Five commercial nurseries were sampled in 2007 to evaluate the grapevine nursery propagation process as a source of Petri disease pathogens (Phaeoacremonium spp. and Phaeomoniella chlamydospora). Samples were taken at four stages of the propagation process: pre-grafting hydration tanks, scissors used for cutting buds, grafting machines and peat used to promote root development. All samples were analysed using two different techniques: nested PCR using specific primers for Phaeoacremonium spp. (Pm1/Pm2) and Pa. chlamydospora (Pch1/Pch2); and fungal isolation by culturing on semi-selective medium. Either Phaeoacremonium spp. or Pa. chlamydospora were detected at any of these stages, and more importantly they were viable since they were detected by isolating on culturing medium. Additionally, the importance of grapevine rootstock mother fields as sources of inoculum in the nurseries was studied. Fourteen grapevine rootstock mother fields were surveyed in 2006 and 2007 for the occurrence of fungal trunk pathogens. A total of 16.4% and 30% of the plants sampled in 2006 and 2007, respectively were infected. Petri disease pathogens (Pa. chlamydospora, Phaeoacremonium aleophilum, Pm. parasiticum) and several Botryosphaeriaceae species (Neofusicoccum parvum, Botryosphaeria dothidea, Lasiodiplodia theobromae, N. australe, N. mediterraneum and N. vitifusiforme) and Phomopsis viticola were isolated. This is the first time N. mediterraneum has been isolated from grapevines and the first report of N. australe, N. mediterraneum and N. vitifusiforme in Spain. This work shows that grapevine rootstock mother plants and the propagation process of grapevine plants should be considered as important sources of inoculum for fungal trunk pathogens, and especially of Petri disease pathogens.

What if esca disease of grapevine were not a fungal disease?

“…The assumption of a wood decomposer community that is specific to damaged plant tissues may also explain why we did not find any of the early esca-associated fungi in nursery plants that were grafted with identical rootstock as the adult plants and with healthy scions sampled from the same adult plants studied here. Indeed, the major risk for potential transmission of fungi associated with esca and young vine decline is generally assumed to be during the grafting process of the grapevine cultivar on a new rootstock Giménez-Jaime et al 2006;Aroca et al 2010). However, if pioneer esca species were indeed fungal saprobes specialized in wood decay, grapevine healthy shoots of the rootstock mother plant and of the selected cultivar used for grafting are unlikely to host any of these fungi.…”

“…It is unclear whether esca and young vine decline are due to these different fungi acting jointly or in succession (Graniti et al 2000). These disease-associated fungi have also been isolated with variable incidence from nursery plants (Casieri et al 2009), rootstock mother vines Aroca et al 2010) as well as from apparently healthy young and adult grapevines (Gonzáles and Tello 2010), leading to the view that these fungi are latent pathogens (Verhoeff 1974). Climatic and edaphic factors as well as host genotype (i.e.…”

Fungal Trunk Pathogens in the Grapevine Propagation Process: Potential Inoculum Sources, Detection, Identification, and Management Strategies

“…Detection of fungi involved in young vine decline and their spread through propagation material has been of particular concern for researchers. The subsequent increase in studies on this aspect has led to the conclusion that planting material is already infected in young vineyards, either systemically from infected mother vines (13,40,53,58,59,80,146,152,161,164,166,186,227) or by contamination during the propagation process (12,13,20,22,66,73,106,154,164,210,212,225,230,232).…”

Prediction model for phenology of grapevine cultivars with hot water treatment

“…The dissemination of contaminated propagation material (rooted cuttings and/or grafted seedlings) has been reported as the main form of dispersal of grapevine trunk diseases (Aroca et al, 2010).…”