The particle flow distributions in the event plane of 3-jet (e+e−→qqˉg) and of radiative 2-jet (e+e−→qqˉγ) events are compared at a centre of mass energy of 35 GeV. The number of particles in the angular region opposite to the gluon in qqˉg events is found to be significantly reduced relative to the number of particles in the region opposite to the hard photon in qqˉγ events. This depletion is expected from the “string effect” observed in 3-jet events. It can be explained within the framework of QCD as arising from soft gluon interference.