Invasive Species Compendium

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Abstract Full Text

First report of Colletotrichum acutatum on citrus in Tunisia.

Abstract

Colletotrichum acutatum, is the main fungal species responsible for the Post-Bloom Fruit Drop of citrus (PFD). In Tunisia, the appearance of the PFD has been recorded in recent years on the newly introduced Navel varieties. Symptoms are characterized by the appearance of brown lesions on the petals followed by a massive drop of young fruits. Isolates from various citrus tissues on PDA medium consistently show the presence of colonies of Colletotrichum spp. colored white to gray with formation of spore clusters, orange to pinkish. Conidia were hyaline, fusiform or rarely cylindrical. The results of the morphological study were consistent with studies reported in the literature on this pathogen. To confirm these results, molecular analyzes using species-specific primer pair, CaINT-2/ITS4 and CaInt2/ITS4 were performed. PCR analysis of genomic DNA from citrus isolates resulted in an amplification product of 490 bp, specific for C. acutatum, further confirming the identity of the pathogen. Based on morphological and molecular characteristics, the isolates from citrus tissues were determined as C. acutatum. This result constitutes a first report of this pathogen in citrus and indicates the importance to be attached to this emerging disease in Tunisia.