Only a handful of papaya farmers are left in South Africa and among them, one of the most seasoned says he foresees giving up papayas in five years' time to focus exclusively on avocados.
"It's a sad situation," says Rodney Cooper of Rodney Cooper Estate in Tzaneen, Limpopo Province, where he grows the fruit almost exclusively for retail. "I've had great enjoyment out of growing papayas."
In 2019 papaya growers across the country started noticing a new ailment in their orchards causing trees to topple over: it was confirmed as Phytophthora palmivora, a fungus elsewhere responsible for cacao black pod rot, resulting in an annual loss of 20 to 30% of the world's cacao crop.
The name 'phytophthora' means plant destroyer.
Phytophthora palmivora has been recorded in at least 138 species of tropical crops and first detected in South Africa in 2005 in ornamental nurseries at Witrivier and Malelane, noted the Agricultural Research Council's Plant Protection in 2020. "The result of our current study is the first record of P. palmivora from papaya in South Africa. Papaya is the most common host to be infected by this fungus in high intensity production areas worldwide."
Right: papaya crown rot caused by Phytophthora palmivora (source: ARC Plant Protection News 116, 2020)
Climate change might have facilitated the jump of the fungus to papayas.
The Agricultural Research Council noted the simultaneous occurrence of the fungus in papaya orchards in production regions over 400 km apart. "This suggests that the disease may be linked to extreme climatic conditions, such as high temperature and severe drought, prevalent in both regions during late 2019. Extreme temperatures and drought conditions prevailed during November and December 2019, ideal conditions for infections by Phytophthora palmivora."
The fungus is at least partly responsible for papaya hectares declining in South Africa (official figures for papaya production in South Africa are hard to come by) and it has spread to all papaya areas.
"There's very little we can do about Phytophthora," Cooper says. "The international knowledge that we've tapped into doesn't give us much light at the end of the tunnel. There's nothing really that's working for it at the moment. Our industry is so small, we don't get anyone really interested in doing research."
He posits that papayas will become increasingly scarce in the long term. "Unless researchers can come up with a solution, for sure we're going to see fewer papayas. It's very likely it could even become a luxury fruit."
He remarks that the only other major pest to papayas – unless there are other subtropical fruit ripening in the vicinity attracting fruit flies – is the unrelated black spot fungus which, he says, they easily manage with a spraying programme.
For more information:
Rodney Cooper
Rodney Cooper Estate
Email: [email protected]