What is one suitable method for pruning a healthy medium-aged tree?

Removing the least vigorous branches from the outside of the crown is a suitable method for pruning a healthy medium-aged tree because this approach promotes the overall health and vigor of the tree. By selectively removing weaker branches, you allow more light and resources to reach the more robust branches, encouraging growth and structural integrity. This method helps to shape the tree and maintain a balanced crown, which is essential for long-term health.

Pruning in this manner can also help reduce the risk of disease by providing better air circulation within the crown, decreasing the likelihood of fungal infections that thrive in crowded environments. Additionally, maintaining a healthy balance among the branches helps support the tree's natural form and improves its aesthetic value.

The other methods, such as removing the largest branches or pruning the entire crown, could cause undue stress to the tree and may lead to poor healing, increased susceptibility to pests and diseases, and an overall decline in health. Discarding only dead wood, while beneficial, does not address issues related to crown density and might overlook necessary maintenance for encouraging vigorous growth.