Australia
March 25, 2011
A study into a little-known fungus is expected to lead to improved future management strategies for blackspot – the most common disease of field peas.
Researchers from the University of Adelaide and the South Australian Research and Development Institute are investigating the Phoma koolunga fungus which is a new component of the blackspot (ascochyta blight) complex.
First reported and described in South Australia in 2009, little is known about the biology or role of this fungus in blackspot, however, it is widespread across SA’s cropping regions and has also been detected in Victoria’s Wimmera region and near Esperance in Western Australia. These are the only known sites for the pathogen in the world.
University of Adelaide research student Amanda Benger, who is involved in a Grains Research and Development Corporation-funded project investigating some of the core biological characteristics of Phoma koolunga, says the fungus can cause severe disease in field peas in controlled conditions.
Speaking at a recent GRDC grains research Update in Adelaide, Ms Benger said the study was looking at the effect of temperature on spore germination and fungal growth, and a series of experiments had been designed to assess the interaction of the fungus with pea plants at a range of temperatures and moisture periods.
“Laboratory studies conducted so far have indicated that temperature has an effect on the germination of spores and the mycelial growth of P. koolunga on agar medium,” Ms Benger said.
“The results suggest that the optimum temperature for spore germination was between 15-25C, and observations so far also suggest that the optimum temperature for mycelial growth was between 15-25C, whereas slower growth was observed at 10C and 30C.
“These results have implications for understanding how environmental conditions influence the germination and growth of P. koolunga.”
Ms Benger said preliminary observations from a temperature by leaf wetness experiment suggested that disease severity increased with longer periods of leaf wetness.
“This indicates that the longer an infected pea canopy stays wet, the more severe the disease is likely to be.
“Ongoing experiments will continue to investigate the effect of a range of temperatures and leaf wetness durations and how these influence severity of disease caused by P. koolunga.”
Ms Benger said outcomes of this project would improve understanding of the fungus and the role it plays in the blackspot complex on field peas.
“The environmental conditions that favour the growth of the pathogen and conditions that lead to disease expression will be identified.
“Ultimately this information will be used to improve disease management strategies in the future.”
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