Resumo. The erva-mate (Ilex paraguariensis A. St.-Hil.) is a species broadly cultivated in southern Brazil and neighboring countries, whose leaves and fine branches, prepared according to the appropriate method, make the mate or "chimarrão", the most popular tea consumed in Brazil and exported around the world. With an increasing planted area, mainly in the last decade, phytosanitary problems caused by pests and disease have increased in this crop and root-rot is becoming one of the main problems. The disease is caused by Fusarium spp. and it causes serious damage to the roots, in the most serious cases, leading to the death of the plant. The erva-mate is a species that inhabits the forest underwood, and cultivation in a homogeneous way to full sun can be a stressful factor for the species causing less growth and development and, also, more susceptibility to root-rot. Therefore, experiments were conducted in the Forest Nursery area belonging to Forest Sciences Department of the Federal University Santa Maria with the objective of confirming these assumptions. The experiment was conducted in a factorial design (2 x 5), composed by Fusarium spp. inoculation and by shading levels. It was verified that plants submitted to lower shading levels or full sun had less development and were more susceptible to the disease. The plants inoculated with Fusarium spp. had less development in comparison with non-inoculated plants, mainly at the lower shading levels.