The arbuscular mycorrhizal fungus (AM fungus),Glomus macrocarpus, and the nematodes, Meloidogyne incognita and Tylenchulus semipenetrans, have negative reciprocal effects on spore production, nematode development and reproduction when coinfecting grape roots. Glomus macrocarpus was antagonistic to Rotylenchulus reniformis development and reproduction whilst the nematode was synergistic to spore production. Glomus macrocarpus alone or in combination with M. incognita or T. semipenetrans increased root protein, total soluble sugars, total carbohydrates and decreased lipids and dry matter. Glomus macrocarpus together with R. reniformis decreased protein, total soluble sugars, total carbohydrates and dry matter and greatly increased lipids. Compared to the healthy control, G. macrocarpus alone or in combination with M. incognita or R. reniformis decreased the N, P and K content of leaves. Glomus macrocarpus together with T. semipenetrans improved N, P and K concentrations but the latter was still less than that of healthy plants.