Elite strawberry plants can only be multiplied by a vegetative method. This explains the great dissemination of parasites, such as viruses, mycoplasmas, nematodes, soil fungi, and tarsonems, which are transmitted directly or indirectly to the descendants. The impossibility of efficiently fighting against such parasites, the introduction of nonresistant cultivars, and international trade have rendered the problem more and more acute. However, most strawberry-producing countries have drawn up a program of certification that takes these various parasites into account.