Which fungal pathogen causes frosty pod rot in cacao?

Moniliophthora roreri causes frosty pod rot in cacao. This basidiomycete pathogen attacks pods of Theobroma cacao, the tree whose seeds are processed into chocolate.

The infection often begins internally, so a pod may look healthy for 40 to 80 days after infection. Dark lesions eventually appear, followed by the disease’s characteristic white, powdery coating. That coating consists of millions of asexual spores, which can spread by rain, wind, water movement, people, and infected pods.

Frosty pod rot is easily confused with two other major cacao diseases. Moniliophthora perniciosa causes witches’ broom, while Phytophthora species cause black pod rot. Together, these diseases are sometimes called cacao’s disease trilogy.

The pathogen was formally placed in the genus Moniliophthora in 1978 after scientists reclassified it from Monilia roreri. A major outbreak in Ecuador in 1918 severely reduced cacao exports, and the disease later spread across much of Latin America.