A field experiment was conducted to determine the effect of four doses (0, 10, 20 and 40 kg/ha) of hydrosoluble Larrea tridentata ethanolic extract applied to solarized and nonsolarized plots, on incidence and disease severity of soilborne phytopathogens on roots of pepper cv. Anaheim. Soil solarization during 50 days in spring resulted in maximal soil temperatures of 55.8°C at 1.3 cm depth and 34.3°C at 10 cm depth on the hottest day of the solarization period. An inhibitory effect on disease severity was observed by solarization alone since the control treatment presented a 120% increase in root damage compared with solarized plots. Solarization treatments amended with 20 kg/ha of Larrea showed slight root damage (2.22%) by soilborne pathogens, however, solarization without L. tridentata extract reported (5.2%) a 134% increase in root damage severity. On the other hand, bare soil plus 20 kg/ha extract presented 5.96% root damage, while, the nonsolarized plots without Larrea extract showed 12.59% root damage, an increase of 567% of root damage by soil phytopathogens in comparison to solarized plots amended with 20 kg/ha of gobernadora extract. Inglés