Colletotrichum clavatum sp. nov. identified as the causal agent of olive anthracnose in Italy

Colletotrichum clavatum sp. nov. identified as the causal agent of olive anthracnose in Italy

Roberto Faedda, Giovanni Enrico Agosteo, Leonardo Schena, Saveria Mosca, Salvatore Frisullo. Gaetano Magnano Di San Lio and Santa Olga Cacciola | View Article Molecular analyses of a large population of isolates, previously identified as group B or genetic group A4 of the Colletotrichum acutatum species complex, mainly of Italian origin from olive, but also from other hosts collected since 1992, confi rmed a well-resolved phylogenetic lineage with distinctive phenotypic characters which can be recognized as a separate species. Based on RAPD genomic fi ngerprinting, ITS and β-tubulin DNA sequences, this species was clearly distinct from C. acutatum sensu stricto, C. fi oriniae and C. simmondsii as well as from the genetic groups A1, A6, A7 and A8, all previously referred to as C. acutatum sensu lato. Group A4 is widespread in Europe, being responsible for olive anthracnose epidemics in some Mediterranean countries, including Greece, Italy, Montenegro, Portugal and Spain; moreover, it causes anthracnose diseases on a wide range of other hosts including about 20 different genera of woody and herbaceous plants, ornamentals and fruit trees. This new anamorphic taxon is described as Colletotrichum clavatum sp....
Colonization of Olive Inflorescences by Verticillium dahliae

Colonization of Olive Inflorescences by Verticillium dahliae

Carlos Trapero, Luis F. Roca, Esteban Alca´ntara and Francisco J. Lo´ pez-Escudero | View Article Verticillium wilt of olive, caused by Verticillium dahliae Kleb., is the most severe disease affecting this crop in most olive growing countries. In this study, the presence of viable structures of V. dahliae in dried inflorescences from wilted olive shoots was investigated. The pathogen was found inside peduncles and flowers, by assessing the number of typical star-shaped microsclerotial colonies formed onto the modified sodium polypectate agar medium. Microsclerotia of V. dahliae were observed inside the peduncles under the stereoscopic microscope. The presence of microsclerotia in these easily decomposable olive tissues shows that infected inflorescences can act as a source of inoculum for Verticillium wilt...
A stem canker disease of olive (Olea europaea) in New Zealand

A stem canker disease of olive (Olea europaea) in New Zealand

R. K. Taylor, C.N. Hale, W. F. T. Hartill | View Article A disease complex, with symptoms that include stem cankers and tip die-back, is reported in New Zealand olives (Olea europaea L.). Bacteria from stem cankers of olive were consistently isolated as pale lemon-yellow colonies on King’s medium B. On the basis of microbiological, molecular, and pathogenicity tests the bacterium isolated was identified as Xanthomonas sp. The bacterial isolates allowed verification of Koch’s postulates on young olive trees. As a result of our findings we suggest that the stem canker on olive is caused by Xanthomonas sp. In addition a fungus identified as Fusicoccum luteum was consistently isolated from stem cankers and tip die-back. In inoculated plants F. luteum occasionally formed cankerous symptoms though not as aggressively as Xanthomonas sp. At this stage it is not clear what role F. luteum has in primary...
Balanced plant nutrition may help reduce anthracnose

Balanced plant nutrition may help reduce anthracnose

Vera Sergeeva | View Article Some olive varieties are more susceptible to anthracnose than others. Warm and wet weather can further aggravate the problem, leading to infections of epidemic-like proportions. Wet weather makes the application of chemical treatments difficult, so it is important to consider the use of other cultural practices for controlling disease, such as selection of cultivar type, pruning, irrigation and fertilisation. Correct variety selection, planting density, irrigation scheduling and balancing the physical and biological properties of the soil are all crucial to producing a highyielding, quality crop. However, the proper nutritional management of olive trees is also very important. The essential nutrients extracted from the soil and required by the plant in relatively small amounts are called ‘minor...
First report of anthracnose and fruit mummification of olive fruit

First report of anthracnose and fruit mummification of olive fruit

H. S. S. Duartea, P. G. C. Cabrala, O. L. Pereiraa, L. Zambolima, E. D. Gonc¸alvesb, J. Vieira Netob, E. M. Zambolima and V. Sergeeva | View Article 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 were observed in olive tree fields in Maria da Fe´ , 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 as Colletotrichum 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.,...