Poster Presentation Science Protecting Plant Health 2017

Insights into Botryosphaeria detections - unravelling its identity and its impact on biosecurity (#203)

Ramez R Aldaoud 1 , Srikanthi S DeAlwis 1 , Quang Q Dinh 1 , Soheir S Salib 1 , Robert R Holmes 1 , Jacky J Edwards 1
  1. Agriculture Victoria, Bundoora, VICTORIA, Australia

Over the past 25 years Agriculture Victoria’s Crop Health Services has recorded more than 350 instances of plant diseases associated with Botryosphaeria-like fungi, mostly from Victoria, and some from the other Australian states. The main hosts have been woody species grown by horticultural and forestry industries. Botryosphaeria fungi usually cause canker lesions, wood staining and tree die-back. Leaves and fruits can also be affected. In most of the cases, Botryosphaeria isolates look similar on PDA media, having a distinctly dark and fluffy growth, which does not discriminate species. Before the advent of molecular diagnostics, Botryosphaeria isolates were rarely identified beyond genus. Molecular identification was first applied to Australian isolates in 2007  (Cunnington et al. 2007) when 30 isolates of this fungus from Victoria and NSW were identified to species, using rDNA-ITS and TEF-1α sequences. Since then, applying these molecular tools combined with morphological traits has proven powerful in unravelling new detections.

In 2017, a Botryosphaeria-like fungus from an apple tree (Vic.)  was identified Dothiorella sarmentorum, and this is a new record of this fungus for Australia. In 2016, Diaporthe novem was isolated from a diseased walnut tree (NSW) and Botryosphaeria stevensii was isolated from a horse-chestnut tree (Vic.), and these are first host records for NSW and Victoria respectively. In 2015, a Botryosphaeria fungus from Callistemon was identified as Neofusicoccum australe, and  Botryosphaeria-like fungi from a walnut tree (Vic.) and a Magnolia tree (Vic.) were identified as Neofusicoccum parvum, and these two are new host records for Australia. The impact of these new detections on biosecurity have been assessed and reported to Biosecurity Victoria. In turn, Biosecurity Victoria reports to the other states where relevant and makes decisions on undertaking follow-up surveys, and containment or eradication, as appropriate.