Don’t overlook mildew threat

Be prepared to treat crops for powdery mildew over the next few weeks, cereal growers have been advised.

While recent cold weather may have held off any immediate threat, higher than normal soil nitrogen following the dry winter and forward crops in some areas provide ideal conditions for the disease, said Procam’s David Ellerton.

“If you are certain of a problem, then go in with a protectant now. Alternatively, wait and see what happens and go in with a curative if necessary – but don’t forget about it, mildew can come back and bite.

“By flag leaf it can be too late with sprays only reaching the upper leaves,” he said.

Growers of more mildew-prone wheat varieties such as Claire, Option, Solstice and Brompton may need to consider a mildewicide at T0 to T1, he said.

“Triazoles and strobilurins are good for septoria and rusts, but they do not deliver sufficient mildew control any more. A separate mildewicide is the only means of targeting the disease.”

Dr Ellerton is also concerned that the inherent resistance of Robigus appears to be declining. “The variety now accounts for approximately 20% of the wheat area and where a mildewicide has not been required in the past, this year could be different.”

Susceptible barley varieties include Saffron, Cannock and Colossus, he added.

For the latest reports on what’s going on in the field, see FWi’s Crop Watch – a weekly roundup of views from a team of agronomists around the country.