Cereal Disease Management with Nick Poole

Flag leaf spray best economic benefit in HRZ

The flag leaf fungicide spray remains the most economically beneficial control measure for cereal disease management in Australia’s high rainfall zone (HRZ).

Research supported by the Grains Research and Development Corporation (GRDC) shows timing is critical when it comes to effectively managing rust and limiting yield loss.

Nick Poole, Foundation for Arable Research research coordinator has been working on disease control research in Australia for eight years and says stem, stripe and leaf rust all prospered in 2010.

He says early control measures for diseases set to hit Australia’s high rainfall zone this spring will depend on measures taken to date.

“We can expect higher pressure this coming spring than we may have noted for some seasons,” he said.

“Our research last year showed again that the flag leaf spray in the longer season HRZ is still the principal spray to win growers economic benefit.”

Mr Poole says whether growers spray or adopt other control measures before the flag leaf spray will depend on what was done at planting.

“If you were to use a long lasting seed treatment or in-furrow fungicide we would expect that in the longer season areas like southern Victoria that would last through until at least growth stage (GS) 31 or 32, the first or second node.

“In other parts of the country we might expect that to go right through until flag leaf stage but we have noticed it may not get us to flag leaf stage in southern Victoria.”

Mr Poole urged growers to examine crops for evidence of rust, particularly at the start of stem elongation (at GS 30, 31 and 32) which is the critical time for early measures before the flag leaf spray is applied.

For the first time in many years, southern Australian HRZ growers were dealing with stem rust which emerged late during the exceptionally wet season.

Mr Poole says valuable management lessons were learnt about the control of stem rust in 2010.

“We did a number of experiments looking at fungicide activity against stem rust and we found it can be controlled in the field but timing is absolutely critical,” he said.

“If you don’t get the fungicide on before the disease gets established, really there is little point putting that fungicide on.

“This is a very aggressive rust and it can attack the crop much later than leaf or stripe rust.

“However growers should be aware that infection may surface earlier this season due to the amount of inoculum built up at the end of last season.”

Mr Poole said stem rust could “strangle” the plant during grain fill right up until maturity because it could infect the true stem of the plant just beneath the ear or penduncle.

He said research showed an economic benefit of fungicide application right up until early grain fill.

“Don’t put the sprayer away early if you are growing the more susceptible varieties,” he said.

“We also found some clear differences with products last year and recommend any stem rust outbreaks be controlled with full label rates.”

Mr Poole also urged growers to make use of genetic resistance by choosing less susceptible varieties.

Where fungicides are poorly timed this is the only protection remaining, he says.

In the three, two minute videos (links to podcats are below), Mr Poole discusses what was learnt from last season, early control measure for 2011 and the importance of genetic resistance.

For more information on GRDC’s investment in HRZ research, visit www.grdc.com.au/hrz.

Nick Poole, FAR research coordinator has recorded three vodcasts for the GRDC high rainfall zone project.

Vodcast 1: What early control measures do you recommend for disease management this season
Vodcast 2: What lessons from the wet 2010 season can growers learn from?
Vodcast 3: The value of genetic resistance in disease management.