Characterization of Fusarium species that affect orange trees (Citrus × sinensis L.) and in vitro biocontrol essays with Trichoderma spp.

Among the most important diseases in citrus are those caused by Fusarium species, which decrease yield and generate significant economic losses. One of the control alternatives that has received much attention in recent years is the use of biological control agents, such as species of the Trichoderma genus. These microorganisms can produce enzymes, secondary metabolites and antibiotics that reduce and restrict the development of pathogens. In Chile, there are few studies on the etiology of Fusarium species affecting citrus and their biocontrol with microorganisms. For that reason, this study attempts to identify the species of Fusarium genus affecting orange trees in the central region of Chile and evaluate in vitro conditions the biocontrol potential of four fungicides based on Trichoderma spp. Therefore, from three orange commercial orchards of cultivars, ‘Lane late’ and ‘Fukumoto’, nine Fusarium isolates were characterized by the presence of beige, yellow, pink, purple and velvety to cottony textures. These isolates produced micro- and macroconidia with one to five septa organized in false heads. The in vitro antagonism tests showed an inhibition percentage between 36 and 54% of mycelial growth in Fusarium isolated when confronted with the four Trichoderma-based fungicides. The previous results are promising for their use in an integrated management strategy for Fusarium spp.