Lemon trees, like many citrus varieties, often develop sharp protrusions along their branches. These natural defenses are common, particularly on younger trees, and can pose a hazard during routine care or harvesting. The decision to remove them balances horticultural risk against personal safety and convenience. Understanding the purpose of these structures allows a gardener to make an informed decision.
The Biology and Purpose of Lemon Tree Thorns
Lemon tree thorns are specialized plant structures that serve a protective function in the tree’s natural environment. Classified as modified stem tissue, they develop at the nodes along the twigs and branches. They act as a physical deterrent, guarding against browsing animals that might graze on the foliage and growing tips.
The presence and size of thorns vary significantly with the tree’s age and type. Thorns are most pronounced on juvenile trees, especially those grown from seed, where the plant’s survival is vulnerable. Once a lemon tree reaches maturity, the number of new thorns produced tends to decrease naturally. Grafted trees often have fewer thorns than seedling counterparts, though the thorny rootstock below the graft union may still produce vigorous suckers.
Horticultural Impact of Removing Thorns
Removing thorns is primarily a choice based on safety and ease of access, as the tree’s overall health is not dependent on these structures. The mechanical act of cutting thorns does not harm the tree, and the impact on growth is negligible. The primary consideration when pruning any part of a citrus tree is the risk of creating an entry point for environmental pathogens.
Each cut breaks the tree’s natural protective bark layer, exposing inner tissues. This wound can become a site for fungal or bacterial infection, such as Pseudomonas syringae, which causes citrus blast. The potential for disease introduction is low but increases in environments with high humidity and cool, wet weather, or if pruning tools are not clean.
Removal is practical when thorns interfere with human activity, such as harvesting or walking along a path. Thorns on low-hanging branches can be safely clipped for convenience and to prevent accidental injury. It is also advisable to remove thorns positioned to puncture nearby fruit, which can lead to spoilage.
Thorns growing on suckers arising from the rootstock below the graft union should be removed immediately, along with the entire shoot. These suckers divert energy from the desired lemon variety above the graft. If the thorny sprout is coming from the scion (the fruit-producing part), the decision to remove the thorn is purely cosmetic or for safety.
Practical Guide to Thorn Removal
If thorns are removed for safety or convenience, the procedure requires adherence to specific horticultural practices to minimize risk. Use sharp, clean hand pruners or shears. Sterilize the cutting blades with a solution like rubbing alcohol or a bleach mixture before starting and between trees to prevent the accidental transfer of disease.
Safety precautions are necessary, including wearing thick gloves, long sleeves, and eye protection. The technique is straightforward: the thorn should be snipped off cleanly at its base where it emerges from the branch. Avoid tearing or ripping the thorn away, as this creates a larger wound that takes longer to heal and presents a greater opening for pathogens.
While some gardeners cut the thorn flush with the stem, leaving a tiny nub can be preferable. This avoids cutting into the main branch tissue and confines the wound to the non-vascularized thorn material, promoting faster callousing. Monitor the cut sites after pruning, as healthy trees will quickly form a protective layer of callus tissue over the wound.