Scottish arable farmers may not have been able to produce the bumper yields of previous years in 2018, but what they missed out on quantity was more than made for in reduced inputs and a much improved end price. This year however, appears to be a completely different ball came, with all to play for in the coming months, according to those in the know.

Speaking at a jointly organised agronomy conference in Perth, SRUC cereal gurus Fiona Burnett and Neil Havis, warned that in contrast to last year's extreme weather which not only saw one of the wettest conditions for winter sowings, but also a summer heatwave with reduced disease pressure, this year's crop has hit the ground running following a decent autumn and relatively mild winter – to date.

Hence, disease is an issue and producers need to be aware of new and emerging pathogens.

"Last year's record breaking summer heat resulted in reduced disease pressure but this is a very different season and we are already seeing an enhanced risk of septoria and yellow rust in winter wheat and rhynchosporium in winter barley as a result of the mild winter," said Prof Burnett, head of knowledge exchange at SRUC.

"Unless we get some hard frosts in the coming weeks, there is probably more justification for a TO spray compared to previous years, but it's not a blanket approach – look at the level of disease present first," she added.

"Extreme weather, disease and the loss of various chemicals to treat them, remain a threat to all growers, and cereal producers should look more to a targeted solution and an integrated pest management (IPM) to control them."

With septoria resistance becoming more of an issue, Prof Burnett highlighted the need to manage the disease as best possible by using multisites to protect other actives and the crop at a cheap price, until new chemistry is launched later next year.

"SDHIs are more effective than azoles on septoria with Imtrex ahead of Vertisan and Proline ahead of Bassoon, with an SDHI + azole mixture achieving the highest level of control," she said adding that Bravo continues to demonstrate good protectant activity.

Commenting on the best chemicals for yellow rust she said azoles and Comet retain good activity against the disease with Elatus Era producing the highest yields. Elatus Era can also be used to control brown rust with Librax which provides increased control compared to relying solely on azoles.

This year is also seeing new challenges with new threats emerging from loose smut, which was seen more commonly in winter and spring crops in 2018, along with light leaf spot which has shown yield losses of up to 20% in wheat with symptoms seen in barley crops both last year and in 2017.

Dr Neil Havis, crop protection leader at SRUC also highlighted the growing challenge in controlling tan spot and head blights which are showing partial resistance to some chemicals.

Of more concern however, is ramularia which is proving especially problematic, with varietal ratings for the disease having been withdrawn from AHDB recommended lists due to the huge variation in disease levels in sites and between sites.

The disease, which is connected with wet weather and stress, has shown various degrees of resistance to the SDHIs, strobilurins, MBCs and azoles, in recent years, with chlorothalonil being the only effective fungicide.

"Climate and environment are key to ramularia, so walk crops regularly to accurately diagnose disease levels and if there is a problem, use cholorothanlonil to manage it at T2," said Dr Havis.

Light leaf spot also has the potential to be an issue, Dr Havis said, with the disease which was first reported in Scotland in the 1970s with yield losses of up to 20% reported in wheat, having been seen in barley crops in 2017 and 2018.

"We have not seen a lot of light leaf spot in Scotland in the past but it does like warm soils and is linked to hot humid weather and trash and weeds," he said adding that it overwinters in the seed and affects the stem base.

Light leaf spot could also be an issue in oilseed rape, although with no disease found in 2018 trials, the risk is lower than average.

Clubroot remains the biggest threat to oilseed rape growers with reports of poor control with resistant varieties continuing. Furthermore, with so many brassicas on the market and hence potential mutations, producers were warned that relying on a resistant variety should not be the first and only recourse of eroding the problem.

Instead, Prof Burnett said alternative non-susceptible crops are the most sustainable long term method of control, when virtually half of all arable fields carry some sort of clubroot.

"Liming can help to reduce the intensity of clubroot but you should also keep accurate crop records of disease occurrence, location and intensity and note where varietal resistance has been deployed in fields to aid long-term planning and help prevent spread," said Pro Burnett.

"Where resistant varieties are used, monitor the crop carefully to assess levels of clubroot present and if infection starts change policy. Buying certified seed does ensure susceptible plant numbers are minimised in a resistant variety seed batch, but it is not advisable to use home saved resistant variety seed.

"Producers should also look to manage volunteers and susceptible weeds within and between oilseed rape crops and wash machinery to include contractors machinery each time it has been in a field," she said.