PHENOTYPIC REACTION TO COLLETOTRICHUM ACUTATUM IN FOUR OLEA EUROPAEA CULTIVARS

The olive tree disease, named in Portugal as “gafa”, is caused by fungi of Colletotrichum genus. Two species of this genus (C. gloesporioides and C. acutatum) were identified as causal agents of the disease. However, our research has pointed out that C. acutatum is the prevalent pathogen on the southern region of the country. A comparative study among four olive tree cultivars, two from Portugal (‘Galega’ and ‘Cobrançosa’) and the other two from Spain (‘Picual’ and ‘Arbequina’) was conducted to evaluate the variability of reaction types to C. acutatum infections. The analysis of phenotypic reactions revealed significant differences between ‘Galega’ and ‘Picual’, with the most susceptibility for ‘Galega’ versus characteristics of resistance shown by ‘Picual’. The cultivar ‘Cobrançosa’ and the cultivar ‘Arbequina’ had performances classified as intermediates, which could be connected with differences on the timing of maturation. Several factors involved in the response of the four olive tree cultivars face to the attack of C. acutatum are discussed in this work, as a contribution to the knowledge of the resistance to “gafa” and, consequently, to the disease management.