By Roger Nicoll
High Plains Virus is expected to be more widespread than the isolated case confirmed so far in Queensland - but experts and growers see little cause for alarm.
The same new testing methods that confirmed High Plains Virus on a wheat plant at the Leslie Research Centre in Toowoomba, are expected to uncover the virus in other wheat growing areas of Australia, according to Dr Graeme Hamilton, Chief Plant Protection Officer with the Australian Government Department of Agriculture Fisheries and Forestry.
"It is likely that High Plains Virus (HPV) has been around in Australia for some time in association with Wheat Streak Mosaic Virus (WSMV) but until now we haven"t had a reliable test to confirm that," Dr Hamilton says.
A number of plants from South Australia returned a positive test for HPV in 1996 but the results could never be replicated or confirmed, explains Dr Hamilton. However, Queensland Department of Primary Industries and Fisheries scientists and Plant Health Australia recently developed a diagnostic protocol for HPV which is likely to be adopted nationally.
"Now that we have a robust protocol we are quickly testing a lot of material that was previously sampled for Wheat Streak Mosaic Virus. There is a very strong link between the two viruses, their symptoms are almost indistinguishable and they have been found to co-occur in parts of the United States."
The carrier for both HPV and WSMV is the wheat curl mite Aceria tosichella, which is widespread in Australia. Symptoms of HPV infection may include stunting, yellowing (chlorosis), mosaic patterns and dead streaks in the later stages.
"While HPV is an important disease in parts of the USA it doesn"t appear to be as great a threat here," says Dr Hamilton. "That is not to say it couldn"t cause losses to some crops from time to time. In places where HPV co-occurs with WSMV, it is a less serious disease of the two and even WSMV is usually not of great concern. So we are confident that it will not have a great impact here and certainly no more than WSMV."
Successful control of HPV can be achieved through methods that disrupt the life cycle of the wheat curl mite, such as removing all host plants for at least two weeks between crops.
For more information:
Dr Graeme Hamilton, 02 6271 6534