Over two consecutive seasons, 16 olive orchards with trees exhibiting dieback symptoms on branches were surveyed in southern Spain. The six dominant fungal species recovered were characterized by means of phenotypic observations, DNA analysis (by sequencing of the internal transcribed spacer, β-tubulin, and large subunit nuclear ribosomal DNA regions), and pathogenicity tests. Additionally, three isolates collected from Tunisian olive trees showing similar dieback symptoms, one isolate of Colletotrichum godetiae, and a reference isolates of Neofusicoccum mediterraneum were included. The resistance of the 11 most important table cultivars to N. mediterraneum and Botryosphaeria dothidea, the causal agent of “escudete” (small shield) of fruit, was studied by the inoculation of branches and immature fruit, respectively. The species Cytospora pruinosa, N. mediterraneum, Nothophoma quercina, Comoclathris incompta, and Diaporthe sp. were identified. Only N. mediterraneum and C. incompta were able to induce the typical dieback symptoms and cankers that affected the development of the plants. The species N. mediterraneum was the most virulent among the evaluated species, although differences in virulence among its isolates were observed. The remaining fungal species were weakly pathogenic to nonpathogenic on plants. According to resistance tests, ‘Gordal Sevillana’ and ‘Manzanilla Cacereña’ were the most susceptible to branch dieback caused by N. mediterraneum. Furthermore, the fruit of ‘Aloreña de Atarfe’ and ‘Manzanilla de Sevilla’ were the most susceptible to B. dothidea. Knowledge of the etiology and cultivar resistance of these diseases will help to establish better control measures.

Olive anthracnose caused by Colletotrichum species causes dramatic losses of fruit yield and oil quality worldwide. A total of 185 Colletotrichum isolates obtained from olives and other hosts showing anthracnose symptoms in Spain and other olive-growing countries over the world were characterized. Colony and conidial morphology, benomyl-sensitive, and casein-hydrolysis activity were recorded. Multilocus alignments of ITS, TUB2, ACT, CHS-1, HIS3, and/or GAPDH were conducted for their molecular identification. The pathogenicity of the most representative Colletotrichum species was tested to olive fruits and to other hosts, such as almonds, apples, oleander, sweet oranges, and strawberries. In general, the phenotypic characters recorded were not useful to identify all species, although they allowed the separation of some species or species complexes. ITS and TUB2 were enough to infer Colletotrichum species within C. acutatum and C. boninense complexes, whereas ITS, TUB2, ACT, CHS-1, HIS-3, and GADPH regions were necessary to discriminate within the C. gloesporioides complex. Twelve Colletotrichum species belonging to C. acutatum, C. boninense, and C. gloeosporioides complexes were identified, with C. godetiae being dominant in Spain, Italy, Greece, and Tunisia, C. nymphaeae in Portugal, and C. fioriniae in California. The highest diversity with eight Colletotrichum spp. was found in Australia. Significant differences in virulence to olives were observed between isolates depending on the Colletotrichum species and host origin. When other hosts were inoculated, most of the Colletotrichum isolates tested were pathogenic in all the hosts evaluated, except for C. siamense to apple and sweet orange fruits, and C. godetiae to oleander leaves.

This is the first study of olive anthracnose in Tunisia, which combines both phenotypic and molecular approaches. Colletotrichum acutatum s.s group was recorded for the first time in the country as the causal agent of olive anthracnose.

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Olive leprosy, caused by the fungus Phlyctema vagabunda, is a classic fruit rot disease widespread in the Mediterranean basin. From 2009 to 2013, new disease symptoms consisting of small circular necrotic leaf lesions, coin branch canker and shoot dieback were observed in Spanish and Portuguese olive orchards showing intense defoliation. Phlyctema‐like anamorphs were consistently isolated from leaves and shoots with symptoms. Representative isolates from affected leaves, shoots and fruits were characterized based on morphology of colonies and conidia, optimum growth temperature and comparison of DNA sequence data from four regions: ITS, tub2, MIT and rpb2. In addition, pathogenicity tests were performed on apple and olive fruits, and on branches and leaves of olive trees. Maximum mycelial growth rate ranged between 0.54 and 0.73 mm per day. Conidia produced on inoculated apple fruits showed slight differences in morphology among the representative fungal isolates evaluated. Phylogenetic analysis clustered all of the Phlyctema‐like isolates in the same clade, identifying them as Phlyctema vagabunda. On fruits, influence of wounding, ripening and cultivar resistance was studied, with cv. Blanqueta being the most susceptible cultivar. On branches, a mycelial‐plug inoculation method reproduced olive leprosy symptoms and caused shoot dieback. On leaves, Koch's postulates were fulfilled and the pathogen caused characteristic necrotic spots and plant defoliation. This is the first time that the pathogenicity of P. vagabunda in olive leaves has been demonstrated.