Walnut trees strongly depend on arbuscular mycorrhizae for their mineral nutrition. In return, these fungi obtain from the trees, sugars and lipids to sustain their growth and reproduction. Scientists Mortier et al. surveyed 40 years of scientific literature on the relationships between arbuscular mycorrhizae and walnut tree roots. The root colonization process leads to enhanced seedling survival and quality. The knowledge of positive and negative feedbacks between walnut planting and the fungi allows developing sustainable walnut agroforestry systems.