Syngenta is recommending a new tank mix to control yellow rust, which is already appearing in some crops this spring, despite the cold weather.
Reports of the disease have already re-emerged in Kent, East Anglia, and up into Lincolnshire and Yorkshire, according to the firm’s Chris Rowsell.
“Two or three years ago we thought three or four frosts would be enough to kill yellow rust infections. But, as a rule of thumb, for the yellow rust to die, the infected leaves themselves must be killed off.
“The snow we’ve had can act an insulating blanket. As soon as temperatures rise to 8C, yellow rust will start producing spores again.”
The mix of Cherokee (cyproconazole + propiconazole + chlorothalonil) and epoxiconazole is aimed primarily for growers at T1 looking to target the heightened risk with extra fungicide activity, says his colleague Rod Burke.
It is in addition to the Cherokee + prothioconazole tank mix Syngenta recommended last season.
“It’s aimed at situations where growers are thinking of using epoxiconazole, but want to something to fortify it with,” explains Mr Burke. “As well as adding three ingredients to epoxiconazole, it also brings complementary activity.”
According to Mr Burke, testing has shown cyproconazole moves at a faster rate in the leaf, so will reach yellow rust infections in unsprayed parts of the leaf quickly.
The chlorothalonil component also provides a different mode of action against septoria tritici. “Many growers would be adding chlorothalonil to epoxiconazole anyway, so there is no extra tank mixing involved.”