With the objective to study the critical period of weed control, free weed growth was permitted in three phenological stages of native peach, cultivated under irrigated conditions in Jerez, Zacatecas, México. In this research, three fertilizer doses were also tested. The experiment was conducted from 1983 to 1985. Weed treatments, as well as fertilizer doses, were used to maximize the agronomical and economical yield. The results showed that the maximum agronomical yield (36 tm/ha) was obtained when the orchard was weed free during the whole year, in combination with a fertilizer dose of 65‑65‑65 kg/ha of nitrogen, phosphorous and potassium, respectively. In contrast, the maximum economical marginal return rate was also found with same weed treatment in combination with the fertilization dose of 34‑34‑34. Furthermore, the effect of weeds at different phenological stages of peach trees is also presented and discussed.