A plethora of diseases could threaten oilseed rape crops entering the flowering period and growers are urged to use a fungicide with wide-ranging activity to keep plants clean.

Once oilseed rape hits the yellow bud stage, sclerotinia is the disease at the forefront of peoples’ minds and typically a fungicide is applied at early flowering to protect against the disease.

However, Kent-based Zantra agronomist Kevin Knight reports light leaf spot being very active, dependent on variety, which makes product choice at the early flowering spray vital.

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He is opting for a product that gives activity on light leaf spot, protection against sclerotinia, but also a range of other diseases including alternaria, botrytis and powdery mildew.

“A co-formulation of prothioconazole and fluopyram [for example, Propulse] fits this remit well,” says Mr Knight.

Timing of application is the most important factor in sclerotinia protection Ryan Hudson, Farmacy agronomist

He adds there is also the option of a strobilurin fungicide, such as azoxystrobin, mixed with a triazole or thiophanate-methyl, which will cover sclerotinia, aid green leaf and pod retention and also add some activity on verticillium wilt.

Variability

In Hertfordshire and Bedfordshire, Farmacy agronomist Ryan Hudson has some variable rapeseed crops, with some in full flower and others hit by pigeons or flea beetle that are further behind.

He says the cool weather and early flowering of forward crops has helped reduce the risk of sclerotina, but he will keep an eye on forecasting tools and the weather to judge his first fungicide applications around yellow bud to petal fall.

“Many crops are quite variable and in these cases a split fungicide programme may be more suitable to cover the longer flowering period. Timing of application is the most important factor in sclerotinia protection,” explains Mr Hudson.

See also: Read our Cropwatch agronomists’ advice in full