Ceratocystis albifundus

The disease known as wattle wilt is caused by the fungus Ceratocystis albifundus. This ascomycete pathogen is responsible for severe vascular wilt and bark necrosis in several tree species. It is a highly aggressive fungus capable of killing healthy trees within a relatively short period under favorable conditions.

The primary hosts of this pathogen are various species of the genus Acacia, particularly Acacia mearnsii. The disease has had significant economic consequences in regions where these trees are grown for timber and bark extract. It impacts both natural forests and managed industrial plantations, threatening the sustainability of the industry.

Symptoms of the infection manifest primarily as trunk and branch lesions. The bark typically shows sunken, necrotic patches that eventually crack open. Gummosis, or the weeping of sap from the infected tissues, is a common defensive response observed on the bark surface. As the infection progresses, the foliage wilts and turns brown, leading to the eventual death of the entire tree.

The dissemination of Ceratocystis albifundus occurs primarily through spores that enter the plant via mechanical wounds. These wounds can result from pruning, hail damage, or insect activity. Environmental factors such as high humidity and temperature ranges suitable for fungal growth accelerate the spread of spores, often mediated by insects attracted to the sap exudates.

The impact of this disease is substantial, as it can cause rapid decline in stand density and timber quality. Management strategies are focused on sanitation and prevention. Key measures include the prompt removal of infected trees to reduce inoculum levels, strictly disinfecting logging and pruning tools, and prioritizing the breeding and selection of Acacia genotypes that demonstrate natural resistance to the pathogen.