Plant decline etiology in poplar short-rotation coppice plantations

Poplar short rotation coppice represents a very good opportunity for the production of bioenergy as a strategy against global changes. In recent years, numerous plantations in Central Italy showed worrying stump mortality of uncertain cause. Investigations have therefore been conducted to determine the etiology and symptomatology of this phenomenon. The external symptoms begin with leaf yellowing and sometimes necrosis, microphyllia, and reduced shoots growth, followed by withering and death of the stump. Upon sectioning of the stump, we detected browning of internal tissues of roots and crown, gradually deepening in. In severe cases, we observed wood decay in the central part of the stump, eventually deepening into the root system. Cultures from the edge of necrotic tissue on PDA yielded isolates of the same fungus. Sequence analysis of the Internal Transcribed Spacer (ITS1-5.8S-ITS2) and of the beta-tubulin gene showed that the isolates belong to the genus Cryptosphaeria. Species identification is still ongoing. Eventually, wood decay organisms belonging to the genera Pholiota and Collibia colonized the tissues as secondary invaders. Future goals will be to identify the species of the pathogen, define the disease predisposing factors and identify possible control measures.