Donald Paterson, agronomist at Scottish Agronomy Blog - 12 December 2019

Mixed weather and the loss of important Plant Protection Products (PPPs) have meant for an unpredictable year for Scotland’s arable farmers, writes Donald Paterson, agronomist at Scottish Agronomy

The weather in 2019 has thrown up many challenges for Scotland’s arable growers. Spring crops were sown into good conditions and received adequate rain and warmth for excellent emergence and tillering. Unfortunately, as harvest approached weather patterns changed with an increase in dull and wet days, leading to lodging in some crops, making harvest a slow and drawn-out process for many.

Despite the testing harvest, yields have generally been above average, particularly for Spring Barley which had an excellent year. Autumn establishment and potato harvest have been especially challenging across the country. A consequence of this is a reduction in the sown area of winter crops, with many hoping for a drier Spring!

The loss of Plant Protection Products (PPPs) is a continuing challenge facing growers of cereals, oilseeds and potatoes. Of major importance to cereal growers is the upcoming loss of the active ingredient Chlorothalonil. This fungicide has been available for use on cereal crops since 1964 and is still providing an important role in reducing Ramularia pressure in Barley and Septoria pressure in Wheat. As a multi-site fungicide, Chlorothalonil has played a crucial role in protecting both new and existing systemic products as part of an anti-resistance strategy. The introduction of wheat varieties with improved disease resistance can help to minimize disease pressure in Wheat. In Spring Barley there are currently no Ramularia resistant varieties or PPPs that provide the same level of control as Chlorothalonil, potentially leading to a reduction in yield in high pressure seasons.

In recent years Neonicotinoid seed treatments have been withdrawn from use on Oilseed Rape (OSR) and more recently on cereals. As a result, the incidence of cabbage stem flea beetle damage in UK OSR crops has steadily increased. Although the Scottish crop has been less affected the total area of OSR grown in the UK has declined to 514,000 ha in 2019, from a high of 749,000 ha in 2012, the year before the Neonicotinoid seed treatment ban 1.  With alternative break crops being less suitable to many arable systems, growing OSR is going to become ever more risky.

More recently, in December 2018, the Neonicotinoid seed treatment, Deter, for the control of Barley Yellow Dwarf Virus (BYDV) in cereals was also withdrawn. BYDV is becoming an increasing problem in early sown winter cereals, as the aphids which transmit the virus are able to survive milder winters. To combat the problem pest monitoring and the use of management tools such as the AHDB BYDV Management Tool, which aims to predict the ideal timing for any insecticide applications, become increasingly important. Ironically, the banning of Deter is likely to lead to even more use of insecticide to suppress aphid activity.  

The loss of the herbicide and desiccant Diquat is going to mark a significant change for Scotland’s potato industry. For many years diquat has played an important role as a herbicide in potato crops, and more importantly, has been the primary desiccant at the end of the season. A consequence of the revocation is that there is likely to be an increase in the use of haulm toppers, which may lead to an extra investment for some, and this practice is not always possible in a wet season.  Growers of seed crops in particular may have to adapt their desiccation systems and timings in order to meet the size specification required by the market.

As a result of the revocation of a range of PPPs over the last few years Scotland’s arable growers have had to adapt their farming practices. The role of IPM will become increasingly important with growers using more disease resistant varieties, increasing crop monitoring and adopting new technologies to produce the safe and affordable products that the public require in an environmentally sustainable way.


1  AHDB Grain Market Daily (05/07/2019), available from, accessed 09/12/2019

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