Botryosphaeria Tree Fungal Pathogens and Their Diversity

Abstract

The genus Botryosphaeria identified in 1863 as saprophytes of dead tissue of woody plants have been described as pathogens of economically important plantation trees in agriculture and native forests. The genus is a species-rich, worldwide distributed occurring on diverse host ranges. Species of the Botryosphaeria are reported as the pathogens of many plantation trees, including species of Acacia, Eucalyptus, and Pinus causing canker and rapid dieback diseases which often end up in death. Botryosphaeria fungal pathogens have cross pathogenicity on different host tree species which enables them important and focus area of research. The taxonomy of Botryosphaeria spp. have been under research, identification of these fungi has generally been based on morphological features of the anamorph that usually seen under the microscope. Characters that are used to classify genera in the Botryosphaeria have mostly relied on the macroscopic features of the ascospores and the conidial features. Currently, molecular techniques such as DNA sequencing involving amplification of ITS region are important for exact identification of the genera to species level. Recent molecular, phylogenetic and morphological findings showed that order Botryosphaeriales is diverse consisting nine families and 33 genera with 23 genera only in the family Botryosphaeriaceae. Botryosphaeria spp. are naturally endophytes associated with tree plants known to cause monocyclic or polycyclic diseases resulting in polyetic epidemics. The factor that makes plants more prone to Botryosphaeria fungal species is assumed to be stress or wounding associated with the host plants. Global climate change driven drought is an important factor that initiate stress resulting in nutrient deficiencies. Botryosphaeria fungal tree diseases can be best managed by ensuring plants are in optimal health through appropriate integration of cultural, silvicultural and fungicidal applications to effectively prevent and control the diseases.