Peruvian Hass avocado growers are trying to promote avocados as a healthy alternative to butter with a competition aimed at sandwich shops and delis.

The ‘add an avocado’ campaign offers shops the chance to win £1,000 in cash if they sell a sandwich made with avocado for at least one month. To qualify, shops have to submit a photo of their sandwich and of their menu via by 31 August.

Meanwhile, rival South African avocado growers have announced they are on target to ship 12.5 million cartons this year, up from just 6.7 million in 2011. At present, eight million cartons have already been shipped, with the last major shipment to Europe set to arrive in October.