The phosphorus content of a field-grown strawberry crop was monitored over one growing season and the allocation of P to different plant parts determined. In the early part of the season, leaves were the major sink for P and this was partly supplied by redistribution from rhizomes. Once flowers were initiated, these became the major sink and their P requirement was satisfied by new uptake. The calculated rates of P inflow to the roots in this phase of growth were so large that it was necessary to postulate not only that P uptake was assisted by mycorrhizas, but that the whole root system, including the old, brown roots, was active. The implications of this conclusion for concepts of vesicular-arbuscular mycorrhizal function under field conditions are discussed.