[en] This paper reports the effect of twenty-five commonly used fungicides in agriculture on two arbuscular mycorrhizal fungi (AMF) present in commercial products of ATENS, S.L.: Glomus intraradices (Schenck &amp; Smith) and Glomus mosseae [(Nicol. &amp; Gerd.) Gerdemann &amp; Trappe], forming the symbiosis with leek plants. Systemic fungicides (Aliette, Beltanol, Caddy 10, Forum, Moncut, Ortiva, Previcur, Ridomil Gold MZ, Ridomil Gold SL, Rubigan, Sinthane, Stroby, Swich, Tachigarem, Teldor, Topas 10 EC, Frupica) and non systemic fungicides (Daconil 75%, Ditiver, Euparem, INACOP, Octag&oacute;n, Parmex, Terrazole and Metaram), started to be applied to soil and leaves at recommended concentrations and frequencies 4 weeks after transplant and AMF inoculation. The effect of the fungicides was assessed by comparing treated and untreated plants that were inoculated with the AMF through quantification of root mycorrhizal colonization. Among the fungicides applied to the soil, Octagon, Ditiver, Parmex and Metaram virtually eliminated the mycorrhizal symbiosis in treated plants, while the mycorrhizal colonization was not affected by the soil treatment with Beltanol, INACOP and Previcur. Three fungicides of foliar recommended application: Rubigan, Frupica, and Sinthane, strongly inhibited mycorrhizal colonization, but Aliette, Forum, Teldor, Swich and Ortiva, did not seem to reduce it substantially. In addition, the work describes the individual effect of each fungicide applied on both, foliage and soil.&nbsp;

[es] Se han evaluado 25 fungicidas comerciales usados com&uacute;nmente en agricultura, sobre dos especies de hongos formadores de micorriza arbuscular (HMA) presentes en productos comerciales de ATENS, S.L (Glomus intraradices (Schenck &amp; Smith), y Glomus mosseae [(Nicol. &amp; Gerd.) Gerdemann &amp; Trappe], en simbiosis con las ra&iacute;ces de pl&aacute;ntulas de puerro. Tanto los fungicidas sist&eacute;micos (Aliette, Beltanol, Caddy 10, Forum, Moncut, Ortiva, Previcur, Ridomil Gold MZ, Ridomil Gold SL, Rubigan, Sinthane, Stroby, Swich, Tachigarem, Teldor, Topas 10 EC y Frupica) como los no sist&eacute;micos (Daconil 75%, Ditiver, Euparem, INACOP, Octag&oacute;n, Parmex, Terrazole y Metaram), comenzaron a aplicarse al suelo y a las hojas de las plantas, 4 semanas despu&eacute;s del trasplante e inoculaci&oacute;n con HMA, usando las dosis y frecuencias recomendadas por el fabricante. Se compararon los efectos de los compuestos fungicidas por medio del an&aacute;lisis de la colonizaci&oacute;n micorr&iacute;cica de las ra&iacute;ces en plantas tratadas y no tratadas. Los fungicidas ensayados con aplicaci&oacute;n recomendada al suelo: Octag&oacute;n, Ditiver, Parmex y Metaram, eliminaron pr&aacute;cticamente la simbiosis micorriza en las plantas tratadas. Sin embargo, la micorriza no sufri&oacute; ning&uacute;n tipo de afectaci&oacute;n con los tratamientos dirigidos a suelo de Beltanol, INACOP y Previcur. Tres de los fungicidas de aplicaci&oacute;n recomendadas por v&iacute;a foliar: Rubigan, Frupica y Sinthane, inhibieron fuertemente la colonizaci&oacute;n micorr&iacute;cica, a diferencia de Aliette, Forum, Teldor, Swich y Ortiva, que no parecen inhibirla de manera substancial. Se describe adem&aacute;s en el trabajo el efecto individual de cada fungicida, aplicado tanto a nivel foliar como de suelo.