Backward winter crops should get the boost they need to get them moving after some warmer weather, much to the relief of Scotland's growers.

But it isn’t without its problems. With spring weed control, fertiliser, spring sowing and T0 sprays only really getting going last week, there is a huge backlog of tasks on the ‘to do’ list.

To see how things are panning out, we went with agronomists John Murrie, of Agrovista; Greig Baird, of Agrii and Bayer’s Grant Reid, for the first of our CropDoctor tours of 2018.

At Coldstream, in the Borders, crops are a little further forward than central and northern areas. Although disease pressure isn’t high, the concern is that some T0 sprays haven’t or will not be applied, possibly stoking up pressure at T1.

Mr Baird felt it was inevitable some winter barley T0 sprays will have been be sacrificed to workload and weather. That probably isn’t too alarming as although mildew can be found it isn’t active and rhynchosporium and net blotch are at low levels, he reckoned

His concern is more to do with how quickly GS32 could hit us. Most winter barley is around GS30, but with warmer weather the time to T1 could be short. “Many malting barleys have had most of their nitrogen and these in particular could race on," he argued.

"Although current disease levels are not as high as in some seasons, rhyncho and net blotch in the lower canopy could spread to new growth. Temperatures might not be ideal for mildew, but we cannot discount it.

“The speed at which crops move to GS32 could be extremely quick and T1 is the ideal time to protect leaf three and eradicate disease on the lower leaves. But miss GS32 and control will be compromised. Winter barley yield is set now, so we must promote tiller retention and ear numbers.”

Where T0 sprays have been missed, he said growers will have little dose flexibility. “With barley the chemistry arsenal is more comprehensive than winter wheat and T1 options include strobilurin, SDHI, morpholine and chlorothalonil fungicides. But whichever combination is chosen, it will need to be supported by a three-quarter dose of prothioconazole.”

Ramularia could also threaten as warm weather could be a trigger for the disease and adding chlorothalonil will be useful, he said.

He also advised using T1 as an opportunity to apply robust growth regulators. “I think a trinexapac-ethyl with chlormequat (3C) mix would be advisable for more susceptible varieties.”

Leaf tissue testing is also important and inevitably some elements will have leached away or become locked up and any deficiencies identified and acted on.

But, Mr Reid warned to be careful with complex T1 mixes. “If you’re looking at a three-way fungicide mix including a mildewicide, plus PGR, sulfonylurea herbicide and some trace elements, too, then it might be a bit hot, especially if we get some late frosts.

"There is also the time to create such mixes. You don’t want to spend too much time with a stationary sprayer.”

Mr Baird said he could not find a winter wheat crop that didn’t have septoria, but yellow rust and mildew found earlier in the season had dried up.

He expected that late-drilled winter wheat will allow T0 sprays to be done in good time, though, but still advocated using SDHIs at T1. “The last thing you want is to be chasing septoria through the season and SDHIs are our most potent protectants."

Winter barley crops in the central region probably have more chance of getting a T0 spray. They are behind those further south, extending spray windows, but otherwise it is a similar picture.

The cold, wet weather impaired root mass and it is important to maintain tillering. Mr Murrie pointed out that winter barley yield potential is still good and it isn’t too late to rectify the effects of the weather. That is something he sees as being worthwhile given feed and straw prices.

“It’s not too late to encourage root mass and help maintain tillers, which is so important for winter barley yield.”

He, too, has concerns with nutrient availability and has seen signs of manganese deficiency, but this can be corrected at T0, or with a separate application.

A PGR at T0 is essential: “From mid-April the temperatures have picked up, despite it still being a little wet. When these crops take up soil nutrients they could really fly and the problem could be keeping some of these crops standing, especially in more fertile soils. I think a second PGR at T1 will be advisable too.”

As is the case further south, winter barley disease is currently lower than in previous seasons. He is finding low levels of rhyncho, but not a great deal else. Mildew was checked by frosts.

For winter wheat it is again lodging risk that concerns him most, an issue magnified with varieties such as Myriad, Leeds and Zulu. Again, a two spray PGR strategy will be employed.

He is finding septoria in the base of winter wheat crops, but little else. However, T0 sprays will include a fast moving azole to protect against rusts as well as septoria and many varieties which are prone to lodging are also weak against yellow rust, he added.

T1 will be equally robust. He feels the septoria threat is too high for anything else but an azole + SDHI + CTL mix.

He warned of the need to protect SDHIs. “Their use increases selection pressure, so we must back them up with a robust dose of an effective azole and CTL.”

Mr Reid added: “When these crops get going, they could race through the growth stages. Having to come back in so soon after a T0 might sound like overkill, but it is important to fully protect leaf three.

"Basing your T1 on the time since T0 could mean leaf three is infected, if the gap is too long.”

Even where T0 and T1 sprays are well timed he also favours an SDHI approach. “In our trials Proline275 (prothioconazole) + CTL is still an effective protectant, but Aviator (prothioconazole + bixafen) is that bit better. If things go awry the extra persistence of azole and SDHI together is an extra safeguard,” he concluded.