For millennia farmers have been improving crops by using their natural genetic variation, selecting the best varieties. Today we face an unprecedented challenge to feed the growing global human population that can only be achieved with major changes in how we combine science and technology with agronomy. Cassava is globally important, annually feeding almost a billion people in 105 countries. It is an important crop for subsistence farming throughout tropical and subtropical regions for smallholder farmers, but especially in sub-Saharan Africa. Cassava is highly dependant on arbuscular mycorrhizal fungi to survive. Mycorrhizal fungi form symbioses with all our major crops. They help plants obtain phosphate from the soil; an essential nutrient that limits cassava production in the tropics. Our Colombian-swiss group have shown a significant effect of Rhizophagus irregularis inoculation on yield of cassava in field conditions in two locations in Colombia. Further, huge differences in the productivity of cassava can be achieved by inoculating it with genetically different lines of R. irregularis. The variation in cassava growth we observed is so large that it would be very unlikely in one generation of plant breeding to see similar variation in cassava growth. By combining agronomy with biology and genetics, we propose a shift in the paradigm of plant breeding that could help to solve the problem of hunger in the world.