Disease control strategies in the West hampered by backward crops

At Bayer’s Callow site in Herefordshire, technical manager Gareth Bubb is reflecting on the impact of yet another difficult autumn in the region, which saw drilling delayed until 13 November. 

“It is looking better here than it did a month ago, but it's backward. 

“I know nationally we've had a better autumn than last season, but here in the West, it was wetter from September to February than it was the year before, which put us all on the back foot,” he says. 

Despite the late drilling date there is disease to be found in the plots, although it may not all be visible. A Bayer CropCheck qPCR test done on winter wheat leaf samples on 28 March revealed the presence of latent Septoria and yellow rust at surprisingly high levels in some varieties.  

“There is disease bubbling away here, which I’m quite surprised about considering it's so late drilled.  

“Which tells me is that we should still look after later-sown crops,” says Gareth. 

Pictured: Septoria identified at Bayer's demonstration site in Callow, Herefordshire

A broad-spectrum fungicide approach, provided by Ascra® Xpro®, Plaxium® or Vimoy® + partner product, will be essential at T1, he adds. 

“Broad spectrum activity is key for the T1 spray because we want to have activity on Septoria, yellow rust, brown rust, mildew, and eyespot.”  

ADAS senior research scientist Chloe Francis is the Crop Doctor for Callow this season and she is quick to note the thinner plant stands on the site. 

“It's later sown, and I think it's pretty typical of fields around the region. There are good bits and bad bits, and everything is a bit thin because of the cold temperatures we've had through February and March - things haven't tillered quite as much as normal,” says Chloe. 

Her plot inspection on 1 April revealed the presence of Septoria and mildew, with Septoria easy to find on the lower leaf layers in almost all varieties. Levels of mildew were variable between varieties. 

“We can find mildew in Extase but it is in other varieties as well, and there is really quite a bit, considering it's been so sunny and dry recently,” says Chloe.  

While Septoria is the key disease concern in the West, it is worth keeping an eye out for yellow rust and eyespot ahead of T1, she adds.  

And after last season’s epidemic, brown rust cannot be overlooked. 

“We are likely to have carryover of brown rust, and while it was mild in the autumn, the cooler temperatures in January and February should have checked it, especially as the frost will have helped reduce inoculum by killing the lower leaf layers that are carrying it. 

“I don’t think brown rust pressure will be as high as last year, but it could still be an issue if it is warm later in the season.  

“Septoria is a tricky one, because it's dry at the moment, which suggests it's lower risk, but the key period for Septoria is end of April through May and into June. Any rainfall we get during that period is after T1, so you've always got to have a level of insurance with your T1, and a broader spectrum approach is useful here.” 

There are echoes this season of 2012, when the weather was initially dry before turning wet after T1, adds Chloe. 

“At the moment it feels like a similar season. We’ve got to think about thin crops and how you deal with them. 

“Think about the disease risk as a whole on these crops and don’t get too bogged down by the fact that they're thinner – you’ve still got to protect them, so you don't lose what potential there is.” 

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