Lichens commonly are found growing on the branches and trunks of pecan
trees, especially in humid areas and river bottom orchards having poor
air drainage.
Lichens are nonparasitic to the pecan tree, but merely attach themselves
to the bark surfaces. Lichens grow equally well on rocks, fence posts,
bricks and other objects. There are several types of lichens that occur
on pecan trees, none of which are damaging except perhaps in appearance
to the trees in cases of extremely heavy infestations, Figure 5.
[Illustration: Figure 5. Lichens commonly found on the bark of pecan
trees. Left, a fan-shaped type. Right, an erect-branched type.]
_Control._—The occurrence of lichens in trees regularly sprayed with
copper-containing fungicides is rare.