More than 900 tonnes of grapes will go to waste after a pest controller sprayed the vines with the wrong fertiliser which will make the product unfit for export. 

The expensive mistake will cost seven vineyards in the Marlborough wine region of New Zealand more than $1.6 million in sales.

Consultant viticulturist Murray Peterson explained a phosphorus and potassium-based fertilizer known as Perk Supa was sprayed on the plants in March, Fairfax reports.

The fertilizer isn’t recommended for use by winegrowers in New Zealand because it leaves a residue which prevents the wine being exported to large markets such as Canada.

The grapes sprayed with the fertiliser will only be able to be used in making wine for the local market.

The fruit will also see a lower price which will set growers back.

According to Mr Peterson the blunder will cost the winegrowers their income for the next two years.

‘It’s not just the loss of the crops but how much they’ve spent, it costs around $8000 per hectare to bring grapes to harvest,’ Mr Peterson said.