Fusarium spp. associated with bud rot of oil palm (Elaeis guineensis Jacq.) in Ecuador

Abstract

Bud rot is considered the most important disease of oil palm (Elaeis guineensis Jacq.) in Panamá, Colombia, Ecuador and Brazil. This disease is characterized by yellowing of young leaves and rot of the flag leaf progressing to the meristematic tissues causing palm death. With the objective of studying bud rot etiology, a survey was conducted during June 2011 in seven different oil palm plantations of the province of Esmeraldas, Ecuador. Sampling was carried out in seven palm plantations and Fusarium spp. were isolated from buds, leaves, meristem tips and roots. Fungal identification was achieved by examination of morphological characteristics and DNA analysis by polymerase chain reaction (PCR). Pathogenicity tests were performed and Koch Postulates were completed with each isolate at the Research Center for Oil Palm in Ecuador. Two-month-old oil palm plants were used for the experiment: CIRAD code 2505 and the hybrids O x G (E. oleifera x E. guineensis), considered susceptible and tolerant cultivars, respectively. The palms were inoculated with 1 ml of 1 x 107 macroconidia per milliliter of Fusarium sp., F. oxysporum and F. solani. Control palms were inoculated with 1 ml of sterile distilled water. After four days of inoculation with F. oxysporum and F. solani, necrotic lesions appeared on the youngest leaves; after twenty-seven days bud rot progressed on the CIRAD code 2504 palms. Fusarium oxysporum and F. solani were re-isolated and identified through cultural characterization and PCR. Fusarium oxysporum and F. solani were found associated with bud rot disease in Ecuador and can be important in the development of the disease.