Lichens are organisms that often go unnoticed, yet they play a significant role in the ecosystem, including fruit orchards. These symbiotic unions between fungi and algae, or cyanobacteria, form crust-like structures on tree bark, providing important ecological services. While lichens are generally harmless, their presence on fruit trees can raise concerns among tree growers. This blog explores the world of lichens, their impact on fruit trees, and effective control and management strategies.

What are Lichens?

Lichens are unique organisms resulting from a mutually beneficial relationship between a fungus and a photosynthetic partner, usually algae or cyanobacteria. They are found on various surfaces, including rocks, soil, and the bark of trees. Lichens come in a variety of forms, from powdery crusts to leafy structures, and they vary in color, including shades of green, gray, and brown.

Lichens and Fruit Trees:

In orchards, lichens are commonly found on the bark of fruit trees. While they are not parasites and do not directly harm the trees, their presence can indicate specific environmental conditions. Lichens thrive in areas with clean air and low pollution, suggesting a healthy ecosystem. However, excessive lichen growth can hinder sunlight penetration to the tree bark, potentially affecting photosynthesis and overall tree health.

Control and Management Strategies:

Improve Air Circulation:

Adequate air circulation is crucial for preventing excessive lichen growth. Pruning branches and thinning the canopy can enhance air movement, creating an environment less favorable for lichen development.

Maintain Proper Nutrition:

Ensure that fruit trees receive appropriate nutrients. Healthy, well-nourished trees are less susceptible to stress, making it more challenging for lichens to establish themselves.

Monitor Soil Moisture:

Lichens prefer damp environments. Regularly monitor soil moisture levels and avoid overwatering, as excessive moisture can promote lichen growth. Implement proper irrigation practices to maintain optimal soil conditions.

Chemical Treatments:

In extreme cases, chemical treatments can be considered. However, it’s crucial to exercise caution, as some chemicals may harm both the lichens and the fruit trees. Consult with a professional arborist or agricultural extension service before using any chemical control methods.

Physical Removal:

If lichen growth becomes problematic, consider physically removing it. Gently scrubbing the affected areas with a soft brush or cloth can help reduce lichen populations. Be careful not to damage the tree bark during this process.

Encourage Natural Predators:

Some insects and birds feed on lichens. Encouraging natural predators in the orchard, such as birds like chickadees or insects like ladybugs, can contribute to controlling lichen populations.


While lichens on fruit trees are generally harmless, their presence can serve as an indicator of environmental health. Implementing proper orchard management practices, including improving air circulation, maintaining proper nutrition, and monitoring soil moisture, can help control lichen growth. Chemical treatments should only be considered as a last resort, and it is crucial to seek professional advice before using them. By understanding the symbiotic relationship between lichens and fruit trees, orchardists can strike a balance that promotes a healthy and thriving ecosystem.

by Amir Rezazadeh

Source: UF/IFAS Pest Alert

Note: All images and contents are the property of UF/IFAS.

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