Should you worry about lichens, moss, algae on trees?

Now that deciduous trees are bare, trunks and branches have taken center stage, and you might be noticing nuances and irregularities that evaded your attention over the summer. For instance, what are those green masses growing on your trees?

Those growths could be either lichens, moss or algae, and the good news is that none are cause for alarm.

Because they usually grow on stressed or declining trees, many people assume these organisms are responsible for making their trees sick. But they aren’t parasitic; they’re opportunistic, which is to say they like to grow on trees that are already ailing or growing in poor conditions.