**2.4. Susceptibility to** *Camarosporium dalmaticum*

Iannotta et al. (2006d) found a different level of susceptibility among cultivars for fruit rot disease. In particular, a low susceptibility was observed for cvs. Frantoio, Tonda di Strongoli and Dolce di Rossano. On the contrary, cvs. Ascolana tenera and Nostrana di Brisighella showed a high susceptibility (Table 8). Since the cultivars displaying the lowest susceptibility to the fungus are the same which show the lowest susceptibility to olive fly attacks, a direct correlation between could be hypotised. Also data concerning non-Italian cultivars show a different behaviour. In fact, cvs. Arbequina, Hojiblanca and Picual are the


less infected and cv. Gordal sevillana the most affected by mycosis (Table 9). The study proves the utility of further investigations in order to characterize the different cultivars behaviour in relation to their parasites, so as to define their specific susceptibility.

92 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

**Table 7.** Percentage of infected leaves (FI%) and percentage of surface occupied by symptoms on leave's surface (SI%) of 35 cultivars (from Iannotta and Monardo, 2004). Letters indicate significant

Iannotta et al. (2006d) found a different level of susceptibility among cultivars for fruit rot disease. In particular, a low susceptibility was observed for cvs. Frantoio, Tonda di Strongoli and Dolce di Rossano. On the contrary, cvs. Ascolana tenera and Nostrana di Brisighella showed a high susceptibility (Table 8). Since the cultivars displaying the lowest susceptibility to the fungus are the same which show the lowest susceptibility to olive fly attacks, a direct correlation between could be hypotised. Also data concerning non-Italian cultivars show a different behaviour. In fact, cvs. Arbequina, Hojiblanca and Picual are the

statistical differences (P<0.01; ANOVA test).

**2.4. Susceptibility to** *Camarosporium dalmaticum*

**Table 8.** Mean values concerning *C. dalmaticum* infection referred to each Italian cultivars. Letters indicate significant statistical differences (P<0.01; ANOVA test). (from Iannotta et al., 2006d, modified).


**Table 9.** Mean values concerning *C. dalmaticum* infection referred to each non-Italian cultivars. Letters indicate significant statistical differences (P<0.01; ANOVA test). (from Iannotta et al., 2006d, modified).

Trials performed by Iannotta et al. (2007a) in the collection field of the CRA OLI compared susceptibility to *Camarosporium dalmaticum* of cultivars planted in the same environmental

and agronomic conditions (Fig. 2). The investigation has been performed in 2005 by analyzing 10 cultivars, in the experimental olive plantation made up by a cultivar collection consisting in 20-years old plants. Observations were carried out detecting on 200 drupes per cultivar the infection level (%) of *C. dalmaticum* by direct observation of drupes. Samples were collected in three different period during fruit ripening (03rd October, 04th November and 5th December).

Susceptibility of Cultivars to Biotic Stresses 95

Results display a different susceptibility of investigated genotypes in relation to the fungal infection, as indicated by significativity letters concerning analysis of variance (Table 10). The lowest susceptibility in relation to fungal infection has been observed for cv. Tonda nera dolce. Also cvs. Bardhi Tirana, Carboncella di Pianacce and Nociara showed a low susceptibility in relation to the pathogenic fungus infection. The cv. Giarraffa turn out to be the most susceptible cultivar while cvs. Carolea, Cassanese, Gentile di Chieti, Nocellara del Belice and Picholine display an intermediate susceptibility value. Comparison among investigated ripening times for pathogenic fungus emphasise an increase of infection

Verticillium wilt, caused by the fungus *Verticillium dahliae* Kleb., is a vascular wilt with a very large host range. Verticillium wilt is increasing in several Mediterranean countries, and it is very difficult to reduce its incidence because is not easy to apply in the field chemical compounds such as fosetyl-Al, directly inoculated within vascular system. Very little is known about biochemical and molecular mechanisms of olive resistance to the Verticillium wilt. Among investigated aspects, it seems to be very important the role of phenolic methabolism (Baidez et al., 2007; Markakis et al., 2010). Vizzarri et al. (2011) investigated the susceptibility of cvs. Arbequina, Arbosana, Frantoio, Ottobratica, Sant'Agostino and Urano by inoculating them with different isolates of *Verticillium dahliae*. Plantlets of 18 months and 160 cm high, has been inoculated by applying a small square of agar with sporulating fungal hyphae on wounded wood. After inoculation plantlets were observed for one year in a greenhouse. The severity of the disese was evaluated by utilising 5 classes of the percentage of damaged plant and the intensity of symptoms: 0%, healthy plant; 20%, plant with large clorosis and moderate foliar symptoms; 50%, severe foliar symptoms and desiccation of vegetative apex; 75%, desiccation of more than half of the plant; 100% dead plant, without defoliation (Colella et al., 2008). Furthermore, Vizzarri et al. (2011) defined a molecular protocol for studying the expression of gene involved in defense mechanisms of the olive. They utilised plants of 14 months of the cv. Leccino, some artificially inoculated as described above and some non inoculated as negative control. Results showed that genetic resistance of tested cultivars, inoculated with different Verticillium isolates, is subordinated to the

**Table 11.** Results of the genotypic susceptibility assay. Number of plants showing a given range of symptoms. Cultivars and isolates used (10 replicates for each cultivar). (from Vizzarri et al., 2011).

percentages through the season.

**2.5. Resistance to** *Verticillium dahliae*

virulence of the inoculated isolate (Table 11).

**Figure 2.** Location of CRA-OLI experimental field, where several cultivars are planted under the same agronomical and climatic conditions, on the ionian coast of Calabria (Mirto-Crosia, Cosenza, Italy).


**Table 10.** Mean infected drupes concerning *Camarosporium dalmaticum* infection. Letters indicate significant statistical differences (P<0.01; ANOVA test). (From Iannotta et al., 2007a, modified).

Results display a different susceptibility of investigated genotypes in relation to the fungal infection, as indicated by significativity letters concerning analysis of variance (Table 10). The lowest susceptibility in relation to fungal infection has been observed for cv. Tonda nera dolce. Also cvs. Bardhi Tirana, Carboncella di Pianacce and Nociara showed a low susceptibility in relation to the pathogenic fungus infection. The cv. Giarraffa turn out to be the most susceptible cultivar while cvs. Carolea, Cassanese, Gentile di Chieti, Nocellara del Belice and Picholine display an intermediate susceptibility value. Comparison among investigated ripening times for pathogenic fungus emphasise an increase of infection percentages through the season.
