How many squashed bugs on your windscreen does it take before you to find a squeegee?
How many midges in your wine glass does it take for you to pour yourself a fresh glass of wine?
How many fungicide resistant pathogens in your paddock does it take before you avoid the fungicide they’re resistant to?
11 (although dependent on bug size), 4 (unless the wine is too fancy to waste) and hmmmm…
This last question stumped us too. But now, thanks to CCDM research, we’re a step closer.
For years, we’ve become pretty good at knowing whether fungicide resistance is present (or absent) in the paddock.
But how much is there, and what strategy should be used to get on top of it?
CCDM researcher Noel Knight and our Fungicide Resistance Team have been studying 20 barley paddocks in the WA wheatbelt, and can tell those farmers an exact percentage of fungicide resistant net blotch pathogens in the paddock, helping to enable better decision-making for next season.
“In the 20 paddocks, we found fungicide resistance in spot form net blotch to Group 3 (DMI) fungicides to be widespread, while fungicide resistance to Group 7 (SDHI) fungicides appeared to be more regionally isolated,” Noel said.
Noel thinks this research takes us one step closer towards knowing the impact of frequency, and answering questions such as, so I’ve got X% fungicide resistance – what’s the best fungicide strategy?
So what did Noel and the team do?
The team undertook a targeted approach to sampling net blotch in 20 barley paddocks across the low-medium rainfall zone of the WA wheatbelt, each managed with various fungicide strategies.
They used a new method of combining genotype testing (sifting through genetic material of mashed up barley leaves in search of fungicide resistant mutations) and phenotype testing (observing how fungal pathogens grow on different concentrations of fungicides) to get a true understanding of the frequency of fungicide resistant pathogens in the paddock.
Here’s what they found:
Here is a graph showing the percentage frequency of resistant net blotch in each paddock, to both DMI and SDHI fungicides:
Here is a map showing the location of the 20 paddocks, and how they have at least 10% resistance to either DMI fungicides, SDHI fungicides or both:
Now that the growers know what they’ve got, how do they manage it?
“This is our next step, to work out what amount of resistant net blotch is okay to have in your paddock, and what amount needs a rethink of your fungicide strategy,” Noel said.
“For example, would 5% DMI resistance in the paddock be okay to continue with a DMI fungicide program? And what fungicide rotations should be considered?
“We’re now carrying out modelling to find this out, to give growers the answers they need to manage fungicide resistance.”
Check out Noel’s paper or presentation included in the GRDC Grains Research Updates:
Or listen to the podcast: