Arable farmers in the South West should choose appropriate wheat varieties to help cope with the region’s high disease pressure and lack of suitable spray days.
Farmers attending a recent open day in Somerset found that just a slight delay in fungicide timings could have a major impact on yields, emphasising the importance of selecting varieties with strong resistance to Septoria tritici in particular. “The wind and rain have been really challenging this year – it’s been hard work to find any spraying windows,” said host farmer Mark Doble.
Growing 162ha of wheat, barley, oilseed rape, beans and potatoes at Hurcott Farm, Seavington, Ilminster, Mr Doble said the timing of operations was absolutely key.
“This year will also show that a T3 fungicide is completely necessary – I wouldn’t ever go without one.”
Ron Granger, technical arable manager at Limagrain, said that choosing a variety with a high resistance to septoria is essential in the South West, providing security as a buffer for delayed fungicide applications. In the field-scale trials, sponsored by BASF and Agrovista, 12 different wheat varieties were grown with differing fungicide programmes, including a control with no treatment at all.
“We can control disease as long as we know a variety’s susceptibility, but you can spend more money chasing it than by using a preventative,” said Mr Granger. According to Paul Haynes, BASF agronomy manager, varieties with good septoria resistance included Skyfall and Crusoe, LG Sundance, KWS Siskin, Costello and Revelation.
“But this year yellow rust has become a big issue in the South West – a lot of varieties with supposedly good yellow rust resistance have been infected by a new strain of the disease.”
Reflection and Britannia had succumbed particularly badly, warned Mike Rastall, regional agronomist at Agrovista.
“Yellow rust is relatively easy to manage with a full fungicide programme, as our trials have shown.” At T0 (31 March) Mr Rastall recommended chlorothalonil and Ceando, with T1 on 24 April, T2 on 22 May and T3 on 8 June, at a total cost of £148/ha. Although the fungicide programmes varied, BASF’s new Priaxor EC treatment had worked particularly well against septoria, the key disease in the south west, said Mr Haynes.
“It’s triazole-free so you have the flexibility to partner it with other products. The strobilurin pyraclostrobin and the SDHI Xemium have good synergies, and you get the physiological benefits of greening, better water use efficiency and nitrogen uptake,” he added. “With epoxiconazole and fenpropimorph it’s a brilliant combination.”
Last year a 10-day delay in T1 and T2 applications resulted in a 0.3t/ha average yield drop, said Mr Rastall. “This year I think we’ll see big differences as harvest nears.”
The level of septoria and yellow rust in the untreated crops was particularly easy to see. “Last year the untreated yields averaged 9.9t/ha, while treated yields were 13.5t/ha – in 2014 that difference was even more marked,” he added.
“A lot of people are looking to cut back on costs but you just don’t know what the weather’s going to do – having the insurance of a full fungicide programme really is worthwhile.”
Farmers can significantly reduce damaging soil compaction by ensuring their tractor tyres are at the correct pressure. According to Kirk Walker of Mitas Tyres, drivers should set tyre pressures at the minimum possible for the weight of the tractor and trailed implement.
“Typically that would be about 8psi in the field. If the tyre is soft you get more traction and it spreads the weight of the machine,” he said.
However, safe road pressures could be as high as 29psi. “At a soil depth of 6” (15cm), the pressure from road tyre inflation on the ground is 18psi, compared to 8psi on field inflated tyres.”
Not setting the correct off-road tyre pressure squashes the larger soil pore space, reducing oxidation, preventing water penetration and restricting root growth, said Dr Lynda Deeks from Cranfield University.
In dry times that would result in drought stress, and in wet periods would cause surface run-off with potential erosion and loss of nutrients.
New monitor farms for South West
AHDB Cereals and Oilseeds’ regional monitor farms continue to go from strength to strength, with two new farms now hosting meetings near Truro and Blandford.
“We’ve had excellent feedback: 95% of group members said the meetings were a good use of time, 82% had improved their technical knowledge and 72% had identified ways to improve their business,” said cereals and oilseeds manager Philip Dolbear.
“There’s no immediate improvement in commodity prices in sight so farmers need to stop, look at their costs, and put in that management time.”