Correlations between soil sodicity and foliar symptom of wood decay of kiwifruit

Wood decay of kiwifruit (Actinidia deliciosa) is a relatively new disease of complex etiology. This disease has gained much attention in recent years because it has become widespread in kiwifruit-growing areas. Foliar symptoms of the disease are associated with toxins produced by pathogens and develop presumably in response to certain environmental and physiological factors. Vineyard surveys were conducted over nine years in a main Italian kiwifruit growing area, to investigate a potential correlation between soil sodicity and the occurrence of leaf symptoms. Greenhouse trials were also carried out to evaluate physiological parameters potentially associated with the symptoms, as transpiration rate, stomatal conductance, net photosynthesis, and water potential of potted vines grown with different levels of soil sodicity. In the vineyard trials, an increase in soil sodicity significantly augmented the incidence of wood decay of kiwifruit. Higher levels of soil sodicity correlated to increased transpiration and decreased water potential in plant tissues, which in turn can increase toxin translocation and accumulation in the leaves.