When Steve Mbugua uprooted more than 500 coffee trees on his half-acre farm in Nyeri county eight years ago, his neighbours thought he was making a mistake. The farmer replaced them with 500 seedlings of Hass avocados - for which there is now huge export demand - and today makes 400,000 Kenyan shillings (nearly $4,000) a year from his harvest. That is nearly ten times what he earned from coffee.

"I knew I would make money," he said, particularly as warmer conditions and worsening drought make it harder to grow coffee in some parts of Kenya where it earlier thrived. Unlike coffee trees, Mbugua said, avocado trees require little maintenance, and their fruit is a good earner. Coffee prices, on the other hand, have gone the wrong way: the price on global markets dropped from about $2.80 a pound in 2011 to about $1.12 today. And with coffee harvests also varying in the face of harsher and less predictable weather, thousands of coffee farmers are switching to avocados, said Joseph Ntere Njau, former chief of nearby Meru county, one of Kenya's main avocado-growing areas. Avocados' popularity has soared around the world in recent years, driven by increased awareness of their health benefits, experts say. In the United States, for instance, per capita consumption of avocado doubled in the decade to 2006, reaching 3.5 pounds (1.6 kg), and doubled again to 7.1 pounds (3.2 kg) in 2016, according to data from the U.S. Department of Agriculture. Kenyan exports of the fruit have climbed from nearly 39,000 tons in 2015 to about 47,000 tons in 2016, worth around 5.2 billion Kenyan shillings ($52 million), said James Weru, marketing manager at Fair Trade Enterprises Limited, a fresh produce exporter.

Kenya is now Africa's second-largest producer of avocados - behind South Africa, Weru said - with 7,500 hectares under cultivation. Seventy percent of growers are small-scale farmers. About one-fifth of the annual harvest is exported, he said, and goes mainly to markets in Europe and the Middle East.

"(That is) due to the high demand ... as avocado is considered to be a very nutritive fruit and has a lot of health benefits," he told the Thomson Reuters Foundation. It also requires little labour, is resistant to pests and disease, and has a long growing season.