Poster: Diseases of Plants: Disease Detection & Diagnosis
Fungal Species Associated with Olive Dieback of Branches and Evaluation of Cultivar Resistance to Botryosphaeriaceae species
J. Moral (1), C. Agustí-Brisach (2), M. Pérez-Rodríguez (2), C. Xavíer (2), A. Rhouma (3), A. Trapero (2) (1) University of California, Davis, Kearney Agricultural Research and Extension Center, U.S.A.; (2) Departamento de Agronomía, ETSIAM, Universidad d
Over two consecutive seasons, 16 olive orchards with trees exhibiting dieback symptoms of branches were surveyed in Southern Spain. The six most frequent fungal species recovered were morphologically, molecularly (by sequencing of the ITS, TUB, and LSU regions), and pathogenically characterized. The resistance of the 11 most important table cultivars to Neofusicoccum mediterraneum and Botryosphaeria dothidea, the causal agent of “escudete” (small shield) of fruit, was also studied by inoculation of branches and immature fruits, respectively. The species Cytospora pruinosa, N. mediterraneum, Nothophoma quercina, Phoma incompta, and Phomopsis sp. were identified. Only N. mediterraneum and P. incompta were able to induce the typical dieback symptoms and cankers that affected plants development. N. mediterraneum was the most virulent of the evaluated species although difference of virulence among their isolates were observed. The remaining fungal species were weakly pathogenic on potted plants. According to resistance tests, cv. Gordal Sevillana followed by the cvs. Manzanilla Cacereña and Manzanilla de Sevilla were the most susceptible to branch dieback caused by N. mediterraneum. Furthermore, the fruits of cv. Aloreña de Atarfe followed by those of cvs. Ocal 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.