OILSEED RAPE growers must look closely at the type of spray nozzle they use in order to optimise disease control and water use efficiency, Syngenta has advised.

Results from farm trials of the firm’s latest Hawk nozzle found that retaining spray in the upper canopy helped achieve better sclerotinia and alternaria control and kept pods green for longer, the firm said.

For effective disease control, 60% of the spray pattern should be held in the top third of the canopy, 30% in the mid-third and little penetrating deeper, the results showed.

“The target zone for application is to coat all the open flowers and unfurling petals with protective Amistar (azoxystrobin) ahead of sclerotinia spores landing on petals,” explained the firm’s Tom Robinson.

“We are also looking to protect the upper leaves where petals may fall and stick to in wet conditions. Some coverage of stems is useful, particularly branch axils where petals are liable to stick, even in dry conditions.”

Cambridgeshire grower Graham Searle was involved with the trials and reports that using the Hawk nozzles also cut water use to 50-80litres/ha, compared to 100litres/ha with Syngenta Amistar nozzles.