Tottenham, Gilgandra and Coonamble will be trial sites to generate an early warning system for stripe rust in crops as reports of the infections are expected to increase across the region. 

Ongoing rain and the survival of significant green bridge over summer have created conditions for stripe rust to thrive across local crops, but farmers and agronomists are still at a loss to identifying the disease ‘pathotype’ without lengthy lab investigations. 

This season, Grain Orana Alliance (GOA) are conducting trials to determined if they can serve as an early warning system for growers to help indicate dominant stripe rust pathotypes in different cropping areas. 

GOA CEO Maurie Street said rusts are highly mobile wind-borne pathogens and move readily across the landscape. 

“The trials will be monitored regularly and if stripe rust occurs, we’ll be able to make an informed opinion on what pathotype is likely present, but we will also send samples away to the University of Sydney to confirm the pathotype,” Mr Street said. 

“This information will help growers understand which other varieties may be at immediate risk of infection in an area, giving them a head start to implement a management strategy,” he said.  

The several pathotypes of rust stripe can impact varieties differently, so while a wheat variety may be resistant to one pathotype, it may be highly susceptible to another. 

The diversity of rust type makes preventing infections a challenge for growers. 

Mr Street said these trials were developed in response to feedback from growers who were concerned about the turnaround between sending crop samples away to finding out what pathotypes were impacting their crops.  

“We thought about how we could address the problem and generate an early warning system to help growers respond to the threat of stripe rust in conducive conditions,” he said.  

NSW Department of Primary Industries Senior Plant Pathologist Steven Simpfendor said that growers have noticed high occurrences across emerging crops, even in moderately resistant varieties such as Lancer. 

“We’re seeing an early epidemic this season - growers wouldn’t usually be reporting infections this early on but the significant green bridge they experienced over summer has supported earlier inoculum development.  

“This has meant there’s significantly more seedling infections this year, including in RMR varieties, but growers who selected more resistant varieties to help manage the disease shouldn’t be too alarmed. 

Dr Simpfendorfer said growers should be out in their paddocks assessing crops closely and making informed fungicide decisions to help manage the disease while crops are most vulnerable at early growth stages.  

“Growers should be proactive and consider applying an early fungicide to manage seedling infections in later sown wheat crops as all varieties are susceptible at this stage. But once resistant varieties establish more and their adult plant resistance genetics kick in, they’ll start to look after themselves.” 

Globally, it is estimated that over five million tonnes of wheat are lost each year to stripe rust alone.