EVEN THOUGH disease might not be prevalent this early in the year, early fungicide applications are still going to be essential, Hutchinsons' technical development director, David Ellerton, has insisted.

Septoria is still present on lower leaves in many crops and given the challenges of controlling established disease with existing triazole and SDHI chemistry, it is vital growers adopt a strong protectant approach from the outset, he pointed out.

The identification of new brown and yellow rust races that resulted in the downgrading of resistance ratings for several important varieties has further heightened the need to keep crops protected, he added.

His northern regional technical manager, Cam Murray, added: “Disease pressure isn’t huge at present, but we’ve seen before how quickly the situation can change. Fungicides don’t offer the same curative ability as in the past, which is why it’s so important to remain in a protectant situation,” he argued.

“Yellow rust, in particular, can destroy your crop within two weeks if you get control wrong. By the time you see rust sporulating in the crop, disease levels are probably 10-times worse within the leaf. But if you tackle rust early, it is relatively easy to control.”

In contrast to much of England, he said conditions have been relatively mild north of the Border, causing mildew to be prevalent on older leaves of wheat and barley.

“Some susceptible crops will need mildew control once they reach stem extension, however it really needs controlling at T0, so is something to watch. If you think it needs control at T0, a morpholine component will be justified – in high-risk crops follow-up with a specific mildewicide at T1 to prevent disease spreading to new leaves.”

In winter wheat, both Dr Ellerton and Mr Murray said multi-site active ingredients such as chlorothalonil or folpet, plus a triazole should form the foundation of T0 treatments at mid to late tillering to protect newly developing leaves.

Although chlorothalonil is generally more consistent against septoria, folpet also delivers good results and offers additional benefits from its compatibility with tank mix partners. It has been shown to slow resistance development in some trials too, Dr Ellerton noted.

Where yellow rust is a risk, particularly in susceptible varieties, he recommended adding a rust-active triazole such as cyproconazole, tebuconazole or epoxiconazole to rapidly control any disease present.

He added that there may be a case for applying a pre-T0 fungicide based on straight tebuconazole or cyproconazole to the most susceptible varieties or high-risk crops. “If rust breaks out, it is usually fairly straightforward to control providing you knock it down quickly. Don’t be tempted to wait and let disease establish, or go in too early with the main T0 as this will stretch the window to T1 too far and allow disease in," he said.

“The T1 is usually applied in mid to late April, so work back three to four weeks from there for your T0 and then consider if an earlier spray is also needed.”

Early disease control is also particularly important in winter barley to protect the viability of tillers and maintain yield potential, as unlike wheat the crop cannot compensate for losing tillers, said Mr Murray.

An early T0 fungicide applied just prior to GS 30, typically around mid to late March, is crucial and has been shown to consistently deliver a 0.2-0.3t/ha yield response, he says.

Products based on cyprodinil and chlorothalonil are generally the most effective option and allow triazole chemistry to be saved for later in the programme. Fenpropimorph is worth including if mildew risk is high, he pointed out.