How does the presence of lichen on apple trees affect their overall health and productivity?

Lichen on Apple trees can indicate poor tree health, as they thrive in areas with low tree vigor. This can lead to reduced productivity and fruit quality, as the lichen competes with the tree for nutrients and sunlight. Additionally, lichen can create a barrier that blocks sunlight from reaching the leaves, which is essential for photosynthesis and fruit development. Overall, the presence of lichen on Apple trees can negatively impact their health and productivity.