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Rain splash risk for chocolate spot spread

Agronomy Issues
Chocolate spot on winter bean leaves in early spring

With spring conditions triggering new growth, winter bean crops are under pressure from chocolate spot spread from the recent rain events. The mild weather has seen disease development of large lesions on lower leaves.

Growers are reminded that the final application date for the widely used Alto Elite, to prevent chocolate spot infection on clean new leaves, is 20 May this year - along with other fungicides containing chlorothalonil.

Chocolate spot on winter bean leaves in early spring

For disease strategies in 2021 and beyond, however, Syngenta Technical Manager, Michael Tait, reported new fungicide chemistry for pulse crops has been submitted for registration. Trials have shown the Solatenol active is an ideal option for a T1 application, targeting the early development of chocolate spot and ascochyta.

Preparing for the new strategy, he highlighted Syngenta trials last season had also shown that a follow up treatment with Amistar gave its best results from the systemic activity, to protect against rust.

Climatic trends in recent seasons, with periods of prolonged hot, dry weather over the summer, has seen an increased threat of rust developing in bean crops, he pointed out.

Where Amistar had also been used alone as an early T0 treatment, which has been shown to be highly effective in boosting green leaf area and yield, any further application would need to be with a mix partner for resistance management, added Mr Tait.