Acute oak decline in Apulia Region: symptomatology of ultra-rapid tree’s desiccation

Abstract: Acute oak decline is a disease of oak trees, which was first observed in the UK late in the 20 th Century. It can kill oak trees within 4-6 years. The disease is found mostly on mature oak trees, but younger trees can also be affected. Clear symptoms of infected trees are the progressive deterioration and desiccation of the canopy. Looking into the causes of Acute oak decline, it clearly involves a number of agents, particularly beetles and bacteria, but other factors like drought stress, ploughing, herbicide spray drift, fungi and of course old age can also be involved in the decline of oak. There are some key symptoms in the filed: 1. dark weaping patches on the stem (stem bleeds), in early stages only a single or a few bleeds but in advanced cases many bleeding points; 2. Distinctive ‘0’ or ‘O’ shaped exit holes of xylophagous Buprestid and Ceramycid beetles; which lay eggs underneath the bark during the Summer and then those eggs hatch and larvae feed underneath the cambium for up to 2-3 years before they emerge. There appears to be an interaction between microorganism and insects that needs to be investigated. Whatever the cause of the oak decline, it’s clear that although some trees die, others recover, and our aim is to understand why. What we observed in the last years in oak woods of Apulia: the desiccation time reduced dramatically to 1-2 years. Climate change and global warming have certainly had an effect on this accelerated desiccation process. The causes of the Apulian oak decline are currently being investigated and here we report the latest updates of our work.