Association between soil properties and Grapevine Leaf Stripe Disease (Esca Complex) symptom expression. Part I: soil physical, hydrological and chemical characteristics
This study is the first of two companion papers (Part II addresses rhizosphere microbial communities) and aims to investigate the influence of soil properties on GLSD foliar symptom expression by comparing high recurrence of symptomatic vines areas (HRSVAs) and low recurrence of symptomatic vines areas (LRSVAs). The research was conducted in an approximately 1.75-hectare Cabernet Sauvignon vineyard in Tuscany, Italy. Electromagnetic induction (EMI) proximal sensing was combined with kriging-based maps of grapevine leaf stripe disease (GLSD) symptom recurrence over a five-year period, allowing the identification of four vineyard sectors representing contrasting levels of symptom recurrence (high vs. low) and soil apparent electrical conductivity (ECa; medium vs. high). One soil profile was excavated in each sector and characterised through pedological description and physicochemical analysis. GLSD symptoms showed a heterogeneous yet spatially structured distribution, with distinct zones exhibiting contrasting recurrence. Soil properties differed markedly between HRSVAs and LRSVAs. LRSVAs were characterised by clay loam to silty clay loam textures, high lime content, alkaline pH, higher available water capacity (AWC), and lower available manganese concentrations (4.5-4.8 mg/kg). In contrast, HRSVAs had sandy loam to sandy clay loam textures, subalkaline pH, greater soil fertility (higher nitrogen and organic matter contents), deeper root distribution, and higher available manganese concentrations (14.7-14.8 mg/kg). These findings highlight the importance of investigating soil physicochemical properties in relation to GLSD symptom expression, as both macro- and micronutrient availability may be associated with disease dynamics. The higher manganese availability observed in HRSVAs, together with recent evidence that manganese can stimulate the wood-degrading activity of Fomitiporia mediterranea, warrants further investigation into the potential association between soil manganese bioavailability and disease expression. The spatial correspondence between soil heterogeneity and GLSD symptom recurrence highlights the value of high-resolution investigations of soil-plant interactions for improving our understanding of this complex disease.