Studies on the fungal diseases of mango with particular reference to diseases caused by Botryosphaeria species

Abstract

Mango (Mangifera indica) is a promising tropical fruit crop in Italy. In the near future, it is expected that commercial and backyard plantings of mango trees will increase being a gainful crop. Cultivation of mango is concentrated in four provinces (Catania, Palermo, Messina and Ragusa) located in the southern Italy (Sicily). Since the introduction of mango cultivation into Italy in 1990, little information is available regarding its problematical diseases. Thus, the present work represents the first attempt to assess the presence and the diversity of fungal species associated with different symptoms patterns observed on mango trees during a survey conducted in 2009-2010. Several fungi have been isolated and tentatively identified up to genus level. The most encountered isolated fungal taxa were Alternaria spp., Botryosphaeria spp., Colletotrichum spp. and Pestalotiopsis spp. All these fungi except Botryosphaeria spp. were identified based on conidia and culture characters and tested for pathogenicity on mango detached leaves cv. Kensington Pride. The isolated fungi showed to be pathogenic with different degrees in virulence. Other fungi were occasionally isolated with low frequency such as Botrytis sp., Macrophoma spp., Phoma spp., and Stemphylium spp. The present work focused mostly on the Botryosphaeriaceae associated with dieback disease in Italy and in Egypt. In the present thesis, incorporation of morphology and DNA sequence data of ITS and TEF-1a revealed diverse array of Botryosphaeria spp. associated with mango dieback: Neofusicoccum parvum, N. australe, were the dominant species while, N. vitifusiforme and other two novel species Neofusicoccum sp. 3 and Neofusicoccum sp. 18 were less frequently isolated and associated with dieback disease in Italy. The two novel species of Neofusicoccum were phylogenetically and morphologically distinct from the other species. On the other hand, Lasiodiplodia theobromae and L. pseudotheobromae were the most prevalent species associated with mango dieback in Egypt. The two new described species Lasiodiplodia sp. 8 and Lasiodiplodia sp. 10 were less frequently isolated from mango in Egypt. All tested isolates of Neofusicoccum spp. and Lasiodiplodia spp. except the new species were pathogenic to apple fruits as well as mango cv. Kensington Pride seedlings. Additional studies, including, extensive survey and sampling in different geographical are required to understand the ecology of the new species and to determine their role to cause diseases to mango. Furthermore, critical intervention by developing control strategies such as chemical, biological and agricultural methods must be taken in concern.