With many susceptible winter wheat varieties sown and potentially more mildew-prone spring barleys due to be drilled, Dupont’s Laurence Power says appropriate spray timing and application rates will be critical this season.

A long-term protectant mildewicide will be essential to keep inoculum in crops at bay and to minimise the chance of new spores colonising fresh green leaf – and treatment can bring significant returns, he says.

To get maximum benefit, sprays must be applied early, ideally before the disease is visible, adds Mr Power, who believes growers haven’t always been prompt about getting onto crops when mildew has been identified.

“We recommend going in at T0/T1 as the best option with Talius (proquinazid), which has great timing and rate flexibility, and is an ideal tank mix partner with triazoles at the T1 timing. Talius can also be applied right up until GS65 on wheat, and in barley and oats to GS49.

“Backward crops are likely to receive early nitrogen, which will lead to lush spring growth. Spray early to avoid having to chase mildew for the rest of the season.”

Older leaves will die off even if mildew is present, but the key must be to keep the disease off new growth, he says. A preventative treatment, especially on mildew-susceptible varieties, is the key to achieving cost-effective yield response.

“Applying proquinazid at a rate of 0.15-0.25litres/ha should provide the most cost-effective treatment for mildew this spring and will protect foliage that has yet to emerge.”

In the firm’s trials, proquinazid gave longer mildew control than quinoxyfen, fenpropidin and metrafenone, he adds.

“Talius gives at least two weeks extra persistency, which is significant. We’ve seen a yield improvement over standard fungicide programmes leading to an average 4:1 return on investment.”