Colletotrichum infections during flower development and fruit ripening in four olive cultivars
From Firenze University Press Journal: Phytopathologia Mediterranea
Victoria MOREIRA, Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República
María Julia CARBONE, Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República
Pedro MONDINO, Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República
Sandra ALANIZ, Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República
Anthracnose is an important olive disease in olive-growing regions (Cac-ciola et al., 2012; Moral et al., 2014; Talhinhas et al., 2018; Azevedo-Noguei-ra et al., 2020), especially in those with humid climates such as South Africa (Gorter, 1956), Australia (Sergeeva et al., 2008), Brazil (Filoda et al., 2021) and Uruguay (Moreira et al., 2021). Eighteen Colletotrichum species of the species complexes C. acutatum, C. gloeosporioides and C. boninense have been report-ed to be associated with this disease (Talhinhas et al., 2011; Schena et al.,2014; Chattaoui et al., 2016; Moral et al., 2017; Talhinhas et al., 2018; Moreira et al., 2021). In Uruguay, C. acutatum s.s. was found as the prevalent species, followed by C. nymphaeae and C. fioriniae belonging to the C. acutatum species complex, and C. theobromicola and C. alienum belonging to the C. gloeosporioides species complex (Moreira et al., 2 0 21).The most common host symptom caused by anthrac-nose is fruit rot at the ripening stage. Fruit rot causes yield losses and deterioration in oil quality (Moral et al.,2014; Leoni et al., 2018). Infections can also occur from flowering to fruit ripening. During bloom, species of Colletotrichum can infect host plant calices, petals, sta-mens, and pistils causing flower collapse known as blos-som blight (Moral et al., 2009; Talhinhas et al., 2018; Filoda et al., 2021; Moreira et al., 2021). Each infected flower is usually covered with an orange gelatinous mass of Colletotrichum conidia (Sergeeva et al., 2008; Moreira et al., 2021).
If the flower is not destroyed, Colletotrichuminfects the fruit set, remaining as latent until fruits ripen, when the typical soapy fruit is expressed (Moral et al.,2009; Talhinhas et al., 2018), although the importance of these infections for yield losses is unknown.Infected fruits show depressed brown lesions that are rapidly covered with abundant orange gelatinous masses of Colletotrichum conidia. Fruits can be infected from green stages, and these infections remain latent infections until fruit maturation. The infected fruit can fall or remain mummified on trees, serving as a primary inoculum sources for subsequent infections in the next year (Moral et al., 2008; 2014; Mosca et al., 2014; Talhinhas et al., 2018).The Uruguayan climate is characterized by persis-tent high humidity, frequent rainfall (approx. 1,100 mm per year) and moderate temperatures (Leoni et al., 2018; Conde-Innamorato et al., 2019). These conditions favour olive anthracnose development. In addition, 50% of the plantations (currently 2788 ha) are of the Arbequina culti-var (MGAP-DIEA, 2021), which is moderately susceptible to this disease (Moral, et al., 2014; 2017; Leoni et al., 2018). The remaining 50% of olive groves is planted mostly with cultivars such as Coratina, Picual and Frantoio, which have shown no resistance under these climatic conditions (Leoni et al., 2018). These cultivars are mainly used for oil production for export (MGAP-DIEA, 2020).Studies have shown that susceptibility of olive cultivars to anthracnose can be variable (Moral and Trap-ero, 2009; Cacciola et al., 2012; Moral et al., 2014; 2017), and depends on the Colletotrichum species (Talhinhas et al., 2015). Fruit susceptibility varies according to developmental stage (Moral et al., 2008; Moral and Trapero, 2009; Talhinhas et al., 2015; Moral et al., 2017).
Nevertheless, information is limited on the susceptibility of different fruit maturity stages and different cultivars to Colletotrichum. Although flowers can be infected by Colletotrichum (Moral et al., 2014; Kolainis et al.,2020; Moreira et al., 2021), there have been no studies that indicate when in flower differentiation the flow-ers become susceptible. Knowing when the first infec-tions occur at flowering and their potential incidence is important so anthracnose management strategies can be developed, including those based on fungicides.The present study focused on evaluating the suscep-tibility to five Colletotrichum species of the Arbequina, Coratina, Picual and Frantoio olive cultivars, the major cultivars produced in Uruguay. The study concentrated on flower development and fruit ripening host stages.
DOI: https://doi.org/10.36253/phyto-14087
Read Full Text: https://oajournals.fupress.net/index.php/pm/article/view/14087
