This was a summer scholarship aimed at providing some experience/expertise to University of Southern Queensland student, Johanna Nielson in pathology starting with a well known pathogen.

Black root rot, a widespread disease throughout New South Wales, is a seedling disease caused by Thielaviopsis basicola. Infection of cotton seedlings by this fungal pathogen symptomized by black, discoloured roots, damages cortical tissue, resulting in slow, stunted growth. Incidence of black root rot is increasing in the Namoi valley. The growth rate and colour of isolates in culture from six major NSW cotton production regions were assessed to determine morphological or behavioural differences between regions. Seedling disease severity, and the biomass weights of infected plants were indicators of isolate pathogenicity. No significant difference was found between or within isolates from varying regions in radial growth rates, colony colour, plant biomass production, or disease severity. It is therefore unlikely that pathogenic or morphological variance is the cause of high incidences of black root rot in the Namoi valley.

The aims of this project are to:

1. Single spore the 24 Thielaviopsis basicola isolates in the long term storage culture collection

2. Assess morphology of the selected isolates

3. Test pathogenicity of selected isolates

The objective of this project is to determine whether there are morphological or pathological differences contributing to the increased severity and incidence of black root rot of cotton in the Namoi valley. Objectives are related to Farmers: 1.1 Successful crop protection, and will also expand knowledge of Thielaviopsis basicola amongst researchers and student.