First characterisation of the restricted spring growth syndrome in grapevines in Chile

Restricted spring growth (RSG) is a poorly documented grapevine syndrome that compromises vegetative development, fruit production, and vineyard longevity. Here, we provide the first formal report and characterisation of RSG in commercial vineyards of Vitis vinifera cv. Sweet Globe in Central Chile. Across three affected sites and one control vineyard, we compared vegetative traits, nutritional reserves, and vascular anatomy of symptomatic (Sy) and asymptomatic (As) vines. Field observations revealed that Sy plants developed significantly shorter and thinner basal internodes than As plants, leading to reduced cane vigour. Although leaf nutrient concentrations did not differ between groups, analyses of root reserves indicated that Sy vines tended to accumulate fewer reserves during dormancy, suggesting impaired reserve dynamics. Histological analyses provided critical evidence of vascular impairment, showing that Sy plants developed smaller vessel elements, irregular xylem rays, and disorganised, underdeveloped phloem, frequently associated with callus formation. Screening for potential biotic causes found no association with mites, Pseudomonas, or grapevine trunk diseases. All vineyards tested positive for common viruses (GVA, GRSPaV, GFLV). Hence, pathogens and buds are unlikely to be the cause of the syndrome. Our findings point to an abiotic origin of RSG, shaped by the combined effects of reserve dynamics, cold stress, and vascular tissue damage. Collectively, these results indicate that RSG is a multifactorial disorder that disrupts vascular functionality and reserve accumulation, with consequent impacts on both shoot and fruit development.