Managing Sclerotinia disease in oilseed rape crops will be more critical than ever this season as the rapeseed area in the UK is significantly reduced, experts highlight.

Sclerotinia stem rot stands as a notable threat to oilseed rape in the UK, limiting the movement of water and nutrients through the plant’s vascular system.

Under certain conditions, the disease can slash yields by up to 50% or lead to total loss due to plant mortality.

Sclerotinia sclerotiorum targets crops in the spring, particularly during warm, humid weather when the crop is in bloom. During this time, the disease utilises petals and pollen as a food source to develop.

Efficient disease control heavily depends on protectant fungicides, ideally applied during mid-flowering before significant petal drop occurs.

Ascospores released during sclerotinia germination, rely on petal nutrients for sustenance, highlighting the importance of timely fungicide application to prevent yield losses.

Ruth Stanley, the UK and Ireland country manager at Life Scientific, stresses the critical role of the upcoming weeks in disease control as many crops enter the flowering stage.

“Flowering is relatively on track in rapeseed crops this season and will begin in mid-April. Some forward crops are already starting to flower,” she notes.

“By spraying during mid-flowering, the peak number of flowers receive the fungicide active, which limits disease spread.

“Another challenge with Sclerotinia decisions is that the fungicides only have a protectant role and have to be applied ahead of infection taking place.”

She adds: “In some years, a prolonged flowering period can also mean that a second spray is required to maintain protection – adding to the crop’s growing costs at a time when all expenditure is being scrutinised and has to be justified.

“Sclerotinia is the reason given for almost 30% of total fungicide use in the crop. Against this background, the weather has become less predictable.”

Ruth further highlights the significance of understanding fungicide persistence post-application.

She notes: “As Sclerotinia control relies on protectant treatments, it is important to recognise the persistence of control and how this is linked to dose rate, in order to cover the periods, the crop is at most risk from the disease.”

To deepen comprehension of fungicide persistence and its potential ability, Life Scientific initiated trials in collaboration with ADAS Boxworth.

These trials explored the impact of dosage rates of fungicides Boscler and Aurelia against Sclerotinia over time.