Fungicides must be targeted to specific disease threats, varieties and individual field conditions if growers are to maximise yields this harvest, says farm management company Velcourt. While some may argue this is difficult on large acreages, the firm’s technical director Keith Norman believes it is vital if you want to get the best from products.
“You have to retain flexibility in whatever you do. For example if T0 is missed due to wet weather, it will have a knock-on effect throughout the season.”
He believes product choice and timing will be even more important this spring, given the amount of septoria, brown rust and mildew seen so far. “The worrying thing is the amount of inoculum that’s built up in dead leaves at the base of the crop, which is just waiting to move through the canopy.”
This risk will still be there at the T1 timing, plus growers will also have to consider the added threat from fusarium and stem-based diseases, especially eyespot, he warns. “Product choice is essentially a two horse race between Proline and Tracker. Both are about equal on eyespot, but Proline has got fusarium in its sights and there’s less evidence that Tracker offers this.”
Eyespot control will have added significance at T1 given the relatively large area of susceptible Robigus and Solstice (both rated four), adds Bayer CropScience’s, Gary Jobling. “Einstein and Alchemy also account for a large area and are only rated six, so there’s still potential for the disease to hit these as well.”
Strobs still have a place
Mr Norman believes that strobilurins could play an important role this spring/summer, due to the large amount of brown rust that has already been seen. “Strobs still offer no benefit for septoria control, but they all give long protection against brown rust. If we have a hot and dry May/June – which seems to be increasingly common – they may prove their worth.”
But, strobs are protectant products, not curatives, so a triazole will still be needed to get on top of any disease already in the crop, he advises.
Andrew Lensen, who manages 2400ha of cereals, sugar beet and vegetables near Kings Lynn on behalf of Velcourt, also thinks strobs will have a part to play. “You have got to look at what disease needs treating in the field and the strengths of individual products and varieties. You can’t rely on a blanket approach to get the best out of products.”
Application of Bravo plus triazole at T0 started almost a month earlier than normal this year, highlighting the need for flexibility, he notes. He plans to use a triazole at flag leaf to target whatever specific diseases are present and will also use an ear wash at T3. “We can’t afford not to use an ear wash – it certainly paid for itself last year when we had 6.5in of rain during August.”
The T3 will also help top up brown rust defence in Alchemy, which could be hit badly if the conditions favour the disease, he says.
A T3 will be vital for fellow Velcourt manager, Nick Shorter, who manages 1000ha at Ixworth in Suffolk. Gladiator, Einstein and Alchemy are the main varieties, and with the bulk being grown for seed, maintaining top quality is paramount, he says.
Around 10% of the total area has maize in the rotation, so an ear wash has extra importance to protect against fusarium, he adds. Mr Shorter says fungicide inputs should also be tailored to expected harvest date.
“We know what order we’ll harvest the varieties, so we increase the rates slightly for those that will be done last to maintain protection – typically by 10-20%.”