The time has come for more growers to try varietal mixtures commercially, according to SAC technical director Keith Dawson.
Both SAC and SCRI have been testing varietal blends in the past few years, but uptake has been quite slow commercially.
“There’s probably less than 5% of the area in blends, more in barley than wheat,” Dr Dawson said.
The main potential markets for blends were feed barley and in wheat for distilling.
Currently no maltsters were willing to take malting barley blends, despite some trials suggesting quality could be improved over single varieties.
Blends gave better yield stability, according to SCRI’s Adrian Newton.
“Site-to-site, year-to-year they’ve performed more consistently.
A mixture is always going to give more options to cover whatever conditions are thrown at it.”
He also said blends were less susceptible to disease.
“Complex mixtures gave 50% less disease than you would expect in monocultures in trials last season.
It gives options for reducing doses or missing timings.”
But complexity was important.
“A lot of growers have used two component mixtures, but really you need three, four, five varieties to get the resilience in the crop.”
Research was ongoing to provide tools to design effective mixtures, he said.
“Everyone assumes you need homogenous mixtures, which to produce can be an extra cost, but it doesn’t appear to be necessary.”
Trials last season suggested four-way blends crudely mixed in the drill were more effective.
“They did better in controlling disease and yield.”
Disease appeared to be isolated to patches of susceptible varieties and found it more difficult to spread through the plot than in more homogeneous mixtures.
That was in plots not treated with fungicide, he admitted.
“This year we’ve got some fungicide treated plots as well.”
The role of blends in low input farming was being investigated this season.
It was a system that had different requirements to high input farming, he said.
“Modern varieties have been chosen because they performed under high input conditions, but there is much less information about which ones perform best under low inputs.”
Sixteen varieties plus four blends were being investigated in wheat, while in barley the trials had six individual varieties and four blends.
A low input system could be important if bioethanol took off, as well as where growers were under pressure to cut inputs through regulations, such as NVZs, he said.
“Carbon-accounting the whole crop will be crucial for marketing bioethanol, so inputs are going to be crucial,” he concluded.