Fluxes of interstellar pickup helium have recently been observed to be strongly anti-correlated with solar wind speed in a manner not explained by the standard picture of local pickup and isotropization. We investigate the possibility that spatial diffusion of these ions between solar wind streams could lead to the observed substantial flux changes. However, we find that such spatial transport produces higher fluxes in fast solar wind, and would yield a dependence which is opposite to that observed. ©1999 American Institute of Physics.