## 1 Introduction  
In commercial grapevine (_Vitis vinifera_) growing, vascular diseases (e.g., Eutypa dieback, Botryosphaeria dieback, and esca) are the major factors that can limit crop productivity, fruit quality and vineyard longevity [1, 2, 3, 4, 5, 6, 7]. The causal agents are a set of taxonomically unrelated fungi, which include _Eutrypa latta_, _Phaeocarcinoma minimum_ (syn. _P. aleophilium_), _Phaeomoniella chlamdospora_, _Diplodia seriata_ and _Norfusicoccum parvum_, as some of the most virulent and widespread [8, 9, 10, 11, 12, 13]. Grapevines become infected primarily through pruning wounds [14], either in nurseries during the propagation phase [3] or in vineyards after planting in infested soils. These types of infection have been confirmed through _P. chlamdospora_, providing evidence that this pathogen is also soilborne [15]. Field observations indicate that to date there are no known grapevine cultivars that are resistant to these vascular diseases [5]. Therefore, the degrees of susceptibility range from highly susceptible to low susceptibility [16, 17, 18, 19, 20, 21, 22, 23, 24]. Usually, in plant genotypes that are more tolerant to vascular diseases, despite pathogen colonisation, the disease symptoms are less severe than in sensitive genotypes. This suggests that tolerant plants can neutralise the effects of virulence factors produced by these pathogens [25]. This affects the colonisation of the host by spores transported in the xylem by the sap flow and hyphal growth. These hosts that are more tolerant to pathogens rapidly compensate for the loss of xylem vessels due to pathogen compartmentalisation, by differentiating new functional vessels to maintain sufficient stem water conductivity, which might also explain the tolerance to wilt diseases [26; 27]. In esca, which involves the woody tissues, the plant host can contain the spread of the pathogen through reduction of the spatial lumen of the plant xylem vessels, or by production of gels and development of tyloses that occlude the vessels and entrap the pathogen [27; 28]. A spatiotemporal model of compartmentalisation of vascular wilt fungi in vessels has been hypothesised for annual plants, including tomato (_Solanum lycopersicum_) and cotton (_Gossypium_ spp.) [25]. Among perennial crops, it was observed that in _Ullmus_ genotypes affected by Dutch elm disease, which is a wilt disease caused by _Ophiostoma novo-ulmi_ ([PERSON]) [29], the diameter of the xylem vessels has an important role in resistance to this wilt disease, whereby susceptible hosts have higher proportions of vessels of wide diameters, compared to resistant genotypes [30; 31]. More recent studies have been carried out on xylem characteristics of avocado cultivars from Guatem, Mexican and West Indian botanical breeds susceptible to laurel wilt. These studies evidenced that avocado West Indian race wilt with a larger vessel diameter, and consequently a greater potential hydraulic conductivity, are more susceptible to laurel wilt [32]. Preliminary investigation of [PERSON]'s disease of grape evidenced that two red-berried cultivars, 'Merlot' and 'Cabernet Sauvignon', from the occidentalis profile group, exhibited less disease symptoms and minor xylem vessel dimensions versus white-berried Thompson Seedless cultivar from the orientalis probe group [33]. In grapevine cultivars, the amounts of inoculated _P. chlamydospora_ and the necrotic lesion lengths correlated with vessel size [34]. Then, using the grapevine as a model system, it was demonstrated that vessel diameter is a key determinant of the timing of their occlusion. [35; 36]. Thus, it was suggested that xylem vessel diameter affects disease susceptibility in grapevine, to potentially explain the differences between the highly susceptible and tolerant hosts to esca disease [34; 37]. However, the xylem anatomical properties linked to grapevine genotypes need to be investigated further to confirm such a xylem vessel size-esca relationship.