Premature Fruit Drop in Saw Palmettos Caused by Colletotrichum gloeosporioides

Saw palmetto (Serenoa repens) is a palm species that grows naturally in the southeastern coastal plain of the United States and is most abundant in Florida. Extracts from saw palmetto fruit are sold worldwide in pharmaceutical and dietary supplements in a market valued at $2 billion per year. Lesions on blossoms and fruit and premature fruit drop were first observed in 1996. In 1997, premature fruit drop resulted in 100% loss of fruit in saw palmetto in central and south Florida. In 1998, fruit loss was 8 to 59%. A fungus was consistently isolated from diseased saw palmetto spadices and fruit and identified as Colletotrichum gloeosporioides based on morphological, immunological, and genetic characteristics. Inoculation of spadices of container-produced saw palmettos with C. gloeosporioides resulted in similar disease symptoms and subsequent reisolation of the causal agent. The cross-infection potential of isolates was demonstrated by infection of other hosts. This is the first report of C. gloeosporioides causing disease on saw palmetto.