Lichens are not harmful to fruit trees. They are a tiny plant form that use trees as support. They are not parasitic but are often mistaken for harmful fungi or diseases. Lichens thrive in moist environments. Some fruit trees also like moist environments, such as many apple varieties. There are thousands of kinds of lichens in colors from gray to green to a white fuzzy variety.
Lichens sometimes looks like moss or gray "stuff" growing on the tree. Other forms look like stringy white fuzz on the tree. There are more than a thousand varieties of lichens. Lichens are actually two life forms that cooperate together as one; fungi and green algae. Their many forms include powdery, crusty, scaly, leaf-like lobes, stems or hairy-branched filaments.
Many birds and animals use lichens as nesting material. Reindeer, lemmings and other cold-weather creatures eat lichens. Some insects use lichens as camouflage from predators. It is used to make litmus paper and some dyes. Iceland Moss, a lichen, is ground and made into bread. Lichens in soil make it a good environment for other plants to take hold.
Where Lichens Grow
Lichens grow on many surfaces; walls, rocks, buildings, tree trunks and limbs. They also grow on the ground and assist in soil production. They grow in places that other plants cannot grow due to limited space or nutrients. They do well in very harsh environments and love moisture. Lichens grow well on older fruit trees.
These tiny plants capture nutrients from the air, dust, water and some from the substrate on which they grow. They also feed on bird droppings and insect dung. Lichens grow on just about every surface and use whatever is around them for food. They are extremely adaptable. They grow very slowly when young but increase their rate of growth once they are established.
Lichens will not harm fruit trees, but gardeners might not like the way it looks. Lichens like shade, so pruning a fruit tree's canopy to let in more sunlight is an effective way to deter their growth. Improve the air circulation around the tree trunk by removing any surrounding vegetation. Keep the area clean of debris and plant material.