Fungal Diseases of Citrus in Panama

Abstract

The citrus-growing area in Panama has increased considerably in recent years. Disease problems are frequently observed in orchards, but in most cases their etiology is unknown, complicating the design of effective control strategies. A survey was initiated in 2010, visiting 50 orchards in different regions of the country. In each orchard, symptoms were characterized and samples were collected from the affected organs. Isolations from symptomatic tissues were made on general and selective media and then the fungal isolates were transferred to PDA and V8-juice agar for morphological identification. Molecular identification was carried out on representative isolates by amplifying and sequencing the internal transcribed spacer (ITS) region. Mycosphaerella citri, the causal agent of citrus greasy spot, was isolated from necrotic pustules on the leaves of trees showing chlorosis, and premature defoliation, which were observed in 75% of the surveyed orchards. This disease was found to be the prevalent fungal disease of citrus in Panama. Colletotrichum acutatum was consistently isolated from petals and from fruits that dropped prematurely from lime and sweet orange orchards and pathogenicity tests identified the isolates as the causal agent of Key lime anthracnose disease. Furthermore, melanose on sweet orange leaves and fruits was associated with Phomopsis sp.