  In this paper, we first introduce the concept and representations of modified
$\lambda$-differential Lie-Yamaguti algebras. We then establish the cohomology
of a modified $\lambda$-differential Lie-Yamaguti algebra with coefficients in
a representation. As applications, we investigate the formal deformations and
abelian extensions of modified $\lambda$-differential Lie-Yamaguti algebras by
using the second cohomology group.
