SRA Media Release- New discovery on Chlorotic streak

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New discovery on chlorotic streak disease to lead to better management

Scientists at Sugar Research Australia (SRA) have named the organism responsible for chlorotic streak disease (CSD) in sugarcane, as part of a breakthrough that had been a scientific mystery for almost 90 years.

Most importantly, the discovery is being applied to research that will lead to productivity, profitability, and sustainability outcomes for sugarcane growers and millers.

Dr Kathy Braithwaite, SRA Senior Researcher, is leading a new project aimed at developing a variety resistance screening method for CSD and working to incorporate this into the SRA plant breeding program, so that the industry is provided with more useful data on CSD susceptibility as new varieties are considered for approval.

The project is also working on further developing a diagnostic test and service, which could be integrated with SRA’s current diagnostic service for ratoon stunting disease (RSD). The CSD test already exists as a research tool and is hoped to be extended beyond the research phase and used to assist productivity services organisations in delivering clean plant source material.

“Now that techniques are available to visualise, isolate and quantify the CSD organism experimentally, we can begin to address questions such as how the organism infects naturally through the roots, how it lives within the plant and causes disease, how cells are released back into the soil, and how the organism survives for extended periods outside the plant,” SRA Researcher, Dr Chuong Ngo, said.

Tully grower, Mr Tom Harney, welcomed the news.

“Now that SRA has identified the cause of CSD, there should be better management practices for it: how to prevent it, and how not to get it in the first place,” Mr Harney said.

“There is also an information gap with varieties, and I hope that this discovery improves that.”

As part of the new discovery, SRA researchers have just published two papers on CSD and its cause in the journal Phytopathology, which is considered one of the premier international journals for plant diseases.

In these papers, the researchers including Dr Braithwaite and Dr Ngo, identified the single-celled organism as a type of Cercozoa.

The Cerozoa responsible for CSD is new to science and was given the name Phytocercomonas venanatans. The name means “swims in the veins” and refers to its method of movement and its specific home in sugarcane xylem vessels. It is about 10 micrometres in length, which is about 0.01 millimetres.

The search for the culprit behind CSD dates back to 1929 when the disease was first identified, almost simultaneously in Australia, Indonesia, and Hawaii.

Previous research in the Australian industry has shown yield losses from CSD as high as 40 percent of sugar yield in susceptible varieties, with an estimated cost to industry of $8-$10 million annually, making it one of the most costly diseases facing the industry.