Calonectria diseases on ornamental plants in Europe and the Mediterranean basin: an overview

Species of Calonectria and their cylindrocladium-like asexual morphs are important plant pathogens of agronomic and forestry crops, especially in the tropical and subtropical regions of the world. Calonectria species have been associated with a wide range of disease symptoms on a large number of plant hosts. On horticultural crops, most records of Calonectria species come from the Northern Hemisphere, where they occur mainly in gardens and ornamental nurseries. In Europe and the Mediterranean basin, several species are widespread in nurseries and cause extensive damage to ornamental plants. In the past, identification of species was based on phenotypic characters and sexual compatibility using standardised media. More recently, morphological characteristics, phylogenetic studies (DNA sequence data of the β-tubulin, histone H3 and translation elongation factor-1α gene regions) and mating studies have revealed the presence of several cryptic species complexes that were formerly treated as single Calonectria species. These studies resulted in the introduction of several new species. Other studies aimed at understanding environmental sustainability focused attention on soil solarisation and biological control as means for controlling these pathogens. The potential use of biological control agents (BCAs) and chemicals for controlling Calonectria-induced diseases has recently been addressed. In this review we discuss the Calonectria species detected in Europe and the Mediterranean basin, and the disease management strategies. In view of the mandatory implementation of integrated pest management (IPM) for all European countries by 2014, this paper provides basic information as a platform for the adaptation of more sustainable integrated measures to control Calonectria diseases in European nurseries.