In 2025, a specific action was launched to understand why many oak-dominated forests are in distress. This activity was carried out in collaboration with the Institute for Sustainable Plant Protection of the National Research Council (CNR-IPSP) and the Council for Agricultural Research and Economics – Research Centre for Plant Protection and Certification (CREA-DC).

The initiative involved on-site inspections and surveys in areas where phenomena of plant decline or the deterioration of entire forest sections were reported. The investigations took place in forests located in various areas of Tuscany, often sharing a common factor: the species most affected by this decline are the Turkey oak (Quercus cerris), the cork oak (Quercus suber), and the holm oak (Quercus ilex).

Initial findings have not identified a single common harmful factor or organism responsible for the decline, but rather a combination of different situations. According to the data collected, most of the sites subjected to phytosanitary investigation showed signs of recovery. These include forests growing in unfavorable conditions—with poor and shallow soils—as well as forests in more favorable environments that were, however, affected by persistent outbreaks of phytophagous insects (primarily Lymantria dispar and Tortrix viridana), whose health conditions worsened following episodes of prolonged drought and temperatures above seasonal averages.

However, in some forested areas experiencing severe decline, fungi and bacteria known for their harmfulness to species of the genus Quercus were identified. The pathogenicity of the organisms found is currently under evaluation.

Due to these findings and the widespread nature of the decline—which has also been observed in other Italian regions and European countries—surveillance and research into the causes of this deterioration will continue in the coming years.

SOURCE: Phytosanitary Service of the Tuscany Region