  We present optical monitoring of the black hole candidate XTE J1752-223
during its 2009 - 2010 outburst and decay to quiescence. The optical light
curve can be described by an exponential decay followed by a plateau, then a
more rapid fade towards quiescence. The plateau appears to be due to an extra
component of optical emission that brightens and then fades over ~ 40 days. We
show evidence for the origin of this optical 'flare' to be the synchrotron jet
during the decaying hard state, and we identify and isolate both disc and jet
components in the spectral energy distributions. The optical flare has the same
morphology and amplitude as a contemporaneous X-ray rebrightening. This
suggests a common origin, but no firm conclusions can be made favouring or
disfavouring the jet producing the X-ray flare. The quiescent optical
magnitudes are B >= 20.6, V >= 21.1, R >= 19.5, i' >= 19.2. From the optical
outburst amplitude we estimate a likely orbital period of < 22 h. We also
present near-infrared (NIR) photometry and polarimetry and rare mid-infrared
imaging (8 - 12 microns) when the source is nearing quiescence. The fading jet
component, and possibly the companion star may contribute to the NIR flux. We
derive deep mid-IR flux upper limits and NIR linear polarization upper limits.
With the inclusion of radio data, we measure an almost flat jet spectral index
between radio and optical; F_nu ~ nu^(~ +0.05). The data favour the jet break
to optically thin emission to reside in the infrared, but may shift to
frequencies as high as the optical or UV during the peak of the flare.
