Further evidence on the relationship between sodium content in the soil and incidence of wood decay in kiwifruit

The wood decay is a recent chronic wood disease caused by different fungi with a complex aetiology not cleared yet. This harmful and spread disease is characterized by a correlation between yield losses and foliar symptoms appearance, which in turn have an erratic nature as esca of grapevine. A survey is being carried out on 10-year-old vineyards cv. Hayward, in which the wood decay appeared for the first time in 2003. Each year and in each vineyard, the incidence of the disease was assessed by recording the percentage of vines with foliar symptoms. Moreover, in each vineyard the content of exchangeable sodium in the soil was evaluated. Finally symptomatic or asymptomatic leaves collected at different times during the growing season were analyzed for the content of sodium. The incidence of the disease as percentage of symptomatic vines increased with the content of exchangeable sodium in the soil, but did not seemed correlated with the content of sodium in the leaf.