Trials target new barley disease management options
Fungicides with new modes of action such as the Succinate Dehydrogenase Inhibitors (SDHI’s - FRAC Group 7) are now being commercialised in the Australian market following years of collaborative research supported by the Grains Research and Development Corporation (GRDC).
Research projects such as the GRDC New Fungicide Actives project led by Curtin University have begun paving the way for new product registrations targeting key diseases such as powdery mildew, yellow leaf spot, net blotch and Septoria Tritici Blotch (STB).
Diseases such as powdery mildew and net form of net blotch are common in barley crops across Queensland and New South Wales with yield losses of between 13% and 47% recorded in susceptible varieties.
While varietal resistance remains the best means of control, fungicide options can be an important part of an integrated disease management strategy.
Foundation for Arable Research (FAR) Australia managing director Nick Poole said initial results with the SDHI’s modes of action were proving promising against a range of barley diseases such as net blotches and scald as well as wheat diseases such as yellow leaf spot and STB.
However, he cautioned that the SDHI fungicides were at a moderate to high risk of pathogen resistance development and said it was imperative that industry adhered to anti resistance guidelines and didn’t overuse the products.
“New products with new modes of action are not immune from resistance development, therefore to prolong their activity and that of our existing triazole products we need to use them judiciously and in combination with other control options,” Mr Poole said.
“As more evidence of fungicide resistance (or insensitivity) in triazoles emerges it emphasises the need to use fungicides as part of an integrated disease management approach that capitalises on cultivar resistance and other cultural control measures.”
In the barley field research, the introduction of the SDHI fluxapyroxad as the seed treatment Systiva® from BASF looks set to be a major step forward.
“Previous seed treatments have given partial control of NFNB through controlling infection on the seed, but have lacked systemic activity to give foliar disease control,” Mr Poole said.
“Systiva® potentially changes the management strategies for controlling net form net blotch (NFNB), spot form net blotch (SFNB) and scald in susceptible cultivars and situations, since this new SDHI has good persistence on foliar diseases.
“Results from the FAR Australia led field research shows fungicide activity is evident up to the point that the second fungicide is traditionally applied to barley at awn emergence (GS49) and on occasions through to ear emergence.
“As such the product has the ability to replace the first fungicide timing which has traditionally been applied at early stem elongation (GS30-31).
“Where disease pressure dissipates in the second half of the season, due to lack of rainfall and lower crop canopy humidity there may be no need for a follow up with a foliar fungicide.”
Whilst this maybe an advantage for growers and advisers Mr Poole advises against the continual use of Systiva® year after year since the seed treatment is based on a single mode of action.
“Therefore where barley disease threatens in the following year “ring the changes” and use fungicides with different modes of action so that any mutant strains that might be resistant to SDHI can be controlled,” he said
In addition to Systiva® (based on a single SDHI active ingredient) Mr Poole said there would soon be new foliar applied SDHI’s which come formulated with other fungicide modes of action. In trials these too had shown good activity on the same stubble borne diseases in barley.
For more information on the research into new fungicide active ingredients, read Mr Poole’s presentation to this year’s GRDC Update in Goondiwindi, available in the research and development section of the GRDC website or follow this link.
Nick Poole, FAR Australia
03 5265 1290
Sarah Jeffrey, Senior Consultant Cox Inall Communications
0418 152 859
GRDC Project Code CUR 00019, CCDM/GRDC Program 9 & FAR 00002