  In this article, we prove a joint large deviation principle in $n$ for the
\emph{empirical pair measure} and \emph{ empirical offspring measure} of
critical multitype Galton-Watson trees conditioned to have exactly $n$ vertices
in the weak topology. From this result we extend the large deviation principle
for the empirical pair measures of Markov chains on simply generated trees to
cover offspring laws which are not treated by \cite[Theorem~2.1]{DMS03}.
  For the case where the offspring law of the tree is a geometric distribution
with parameter \sfrac{1}{2}, we get an exact rate function. All our rate
functions are expressed in terms of relative entropies.
