Abstract

RENTERIA-MARTINEZ, María Eugenia et al. Description and comparison among morphotypes of Fusarium brachygibbosum, F. falciforme and F. oxysporum pathogenic to watermelon in Sonora, México. Rev. mex. fitopatol [online]. 2019, vol.37, n.1, pp.16-34.  Epub Aug 21, 2020. ISSN 2007-8080.  https://doi.org/10.18781/r.mex.fit.1808-1.

Abstract Fusarium brachygibbosum, F. falciforme and F. oxysporum have been recently identified as the cause of wilt and death in watermelon plants in Sonora, Mexico. Because of the scarce morphological information about F. brachygibbosum and in order to establish the distinctive macroscopic and microscopic characteristics among the species, the present study described four morphotypes of F. brachygibbosum and their comparison with three of F. falciforme and two of F. oxysporum. The categorization of morphotypes was based on the form of growth, mycelial tonalities and color developed in potato dextrose agar from 32 pathogenic Fusarium isolates in watermelon. The four morphotypes of F. brachygibbosum presented thick walled single and double chlamydospores, intercalary and terminal. Short monophialides and scarce polyphialides; macroconidia with apical slightly hook shaped cells and basal cells with a typical or slight foot shape. The greater thickness of the walls was distinctive in chlamydospores of F. brachygibbosum. The morphology of the macroconidia was different in the three species. A distinctive characteristic of F. falciforme morphotypes was the long and thin monophialides while in those of F. oxysporum was the absence of septa in the microconidia. The size of macroconidia and microconidia was significantly different among the morphotypes but not within the species.

Keywords : wilting; macroconidia; microconidia; chlamydospores; polyphialides..

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