First report of anthracnose and fruit mummification of olive fruit (Olea europaea) caused by Colletotrichum acutatum in Brazil

The olive tree is an arboreal species belonging to the family Oleaceae with recognized importance in the production of olive oils and olives. In December 2008, typical lesions of anthracnose, with mature fruit mummification (Figs. 1, 2) were observed in olive tree fields in Maria da Fé, in the state of Minas Gerais, Brazil . A fungus was isolated directly on potato dextrose agar (PDA) from conidia collected from pink to orange masses on infected fruit. A typical fruit sample was deposited in the local herbarium (VIC 31209). The isolate showed a pink colony on PDA, producing sporodochia with a mass of hyaline amerospores with pointed ends. Based on these morphological characteristics the fungus was identified asColletotrichum acutatum, which has been reported to cause anthracnose on olives trees in other countries and most recently in Australia (Sergeeva et al., 2008). In Brazil , C. acutatum is reported to cause disease on fruit of apple, citrus, strawberry, peach, plum, nectarine, medlar, and on yerba-mate (Kimati et al., 2005).

Identity was confirmed by extracting the DNA of a monoconidial isolate, OLP 570, and amplifying the ITS region of the rRNA by polymerase chain reaction with primer ITS4 and specific primers for C.acutatum(CaInt2; Sreenivasaprasad et al., 1996) and C.gloeosporioides (CgInt; Mills et al., 1992). Isolates of C.acutatum(DAR78874 and DAR78876) and C.gloeosporioides(DAR78875) obtained from Australian olives trees were used as positive controls. TheprimersITS4 and CaInt2 amplified a single DNA product of 490 bp, as expected for C. acutatum(Fig. 3). Pathogenicity was confirmed by placing a 40-mm disk of PDA colonized with OLP 570 on 40 olive fruits that were either intact or slightly wounded. Non-colonized PDA disks were used as negative controls. The inoculated fruits were transferred to Gerbox-type boxes with high humidity and kept in a growth chamber at 25º C. Typical anthracnose symptoms were observed only on the slightly wounded inoculated fruit (Fig. 4) four days post-inoculation with subsequent fruit mummification after a further three days.This is the first report of C. acutatumcausing anthracnose and mummification of olive fruit in Brazil .