Mrs Ashmita Rijal Lamichhane1
1Curtin University, Perth, Australia
Biography:
Ashmita is originally from Nepal and moved to Australia to pursue a Master’s degree in Dryland Agricultural Systems from Curtin University. She joined the Centre for Crop and Disease Management as a research assistant in 2018, and has been involved in projects which uses field, glasshouse, and laboratory-based research to investigate the ecology of Sclerotinia sclerotiorum and the management of sclerotinia stem rot in canola and pulse legumes.
Abstract:
Sclerotinia stem rot (SSR), caused by the necrotrophic fungal pathogen Sclerotinia sclerotiorum, is a major disease of canola and lupins in Australia. Under favourable conditions, sclerotia of S. sclerotiorum can germinate either myceliogenically or carpogenically. The environmental triggers for myceliogenic germination in the field, particularly under Australian conditions, are not well understood.
The study objective was to determine the effect of soil water content (SWC), soil type and isolate conditioning temperature on myceliogenic germination and subsequent growth of two S. sclerotiorum isolates. Two isolates, CU8.20 and CU11.7, were dry conditioned at either 50°C for 60 days or room temperature for 30 days. Isolates were then placed on the surface of both soils at either 115, 100 or 85% SWC. Myceliogenic germination was monitored for 3 weeks, with diameter length measured at day 10.
All sclerotia germinated within 3 weeks with a significant difference in isolate, conditioning temperature, and their interaction recorded. No effect of SWC or soil type was recorded. The experiment was repeated to determine the critical moisture level for myceliogenic germination, using drier SWCs (100, 85, 70, 55 and 40%) in a clay-loam, and sand-loam with one isolate CU8.20 conditioned at 50°C. Sclerotia germination was similar to experiment 1, however, mycelial growth was recorded higher at 40% SWC compared to other SWC (except for 70%SWC). Inconsistent mycelial growth was observed under different SWCs compared to experiment 1. Conducting similar experiments with plants in the pot would determine what percentage SWC is required for basal infection from S. sclerotiorum.