  Let $\mathcal{D}$ be a weighted oriented graph and $I(\mathcal{D})$ be its
edge ideal.
  In this paper, we show that all the symbolic and ordinary powers of
  $I(\mathcal{D})$ coincide when $\mathcal{D}$ is a weighted oriented certain
class of tree.
  Finally, we give necessary and sufficient conditions for the equality of
ordinary and symbolic powers of naturally oriented lines.
