Abstract

PARRA-COTA, Fannie Isela; GARCIA PEREYRA, Jesús; AVINA MARTINEZ, Gabriel Nicolás  and  SANTOS-VILLALOBOS, Sergio de los. First report of Fusarium wilt on Citrus sinensis var. Valencia in the Yaqui Valley, Mexico. Rev. mex. fitopatol [online]. 2019, vol.37, n.1, pp.193-201.  Epub Aug 21, 2020. ISSN 2007-8080.  https://doi.org/10.18781/r.mex.fit.1810-3.

Death of orange trees (Citrus sinensis L. Osberck) var. “Valencia” was observed in the Yaqui Valley, Mexico, in August 2017. In order to identify the causal agent, leaves, branches, and roots from symptomatic trees were collected. Seven fungal isolates were obtained from brown roots, encoded FS1 to FS7. Macro and microscopic characteristics typical of the genus Fusarium were observed in all obtained single-spored isolates, such as: abundant white cottony mycelium and a purple or yellow undersurface on PDA, curved macroconidia widest in the middle of their length, and oval, reniform, elongated oval to obovoid with a truncate base, and septated microconidia. The sequencing of the Internal Transcribed Spacer (ITS) region showed high coverage and similarity (>99%) to sequences of the Fusarium solani species complex (FSSC). The inoculation of 1-year-old orange trees with each obtained Fusarium isolate caused browning of the root vascular system and death of these trees, confirming that those isolates were the causal agents of Fusarium wilt observed in orange tress in commercial fields in the Yaqui Valley. This is the first report of Fusarium wilt on citrus in that region.

Keywords : Fungi; Koch’s postulates; ITS.