Cross-Pathogenicity of Ceratocystis fimbriata on Ochroma pyramidale (balsa) in Ecuador

Abstract

The potential pathogenicity of the ascomycete fungus Ceratocystis fimbriata on Ochroma pyramidale (balsa), a forest species with no prior records of infection by this pathogen in the Ecuadorian Humid Tropics (EHT), was assessed. A strain of C. fimbriata isolated from Tectona grandis (teak) was used to evaluate its ability to induce disease symptoms in two-month-old balsa seedlings. The experiment was conducted in a nursery under a completely randomized design (CRD), comprising three treatments: T1 (inoculation at the stem base), T2 (inoculation at the upper third of the stem), and T3 (control with agar-agar), each with five replicates. Inoculation involved inserting mycelial discs of the pathogen into stem incisions. After 45 days, symptoms such as leaf chlorosis, apical wilting, and vascular tissue necrosis were observed in T1 and T2, with significantly greater necrotic volume and length compared to the control (T1 = 0.32 cm³ and 6.00 cm; T2 = 0.17 cm³ and 4.57 cm; Control = 0.01 cm³ and 0.61 cm). The findings confirm the ability of C. fimbriata to induce pathogenesis in O. pyramidale, representing the first scientific and technical report of this host-pathogen interaction. These results underscore the importance of monitoring and managing this emerging threat to balsa plantations in the region.