Rock salt or Epsom salt can damage and kill tree roots over several weeks and can even assist in removing the tree's stump. However, you need to drill holes or cut into the stump and surface tree roots to inject them properly with the salt. Repeat the process every two weeks until the roots visibly rot away.

Aside from removing dead or diseased branches, you should prune your trees somewhere between every one and three years. Some people—particularly commercial farmers—prune their apple trees yearly to produce higher yields. This is the best way to promote tree health. That said, the average homeowner can get away with hard-pruning their mature apple tree every other year or every three years. 

Yes, it is highly recommended to remove tree stumps. Leaving them in the ground can lead to several problems, as they are not only unsightly but can also reduce your property's value. Stumps can obstruct landscaping plans, make mowing difficult, and hinder new growth. More importantly, they are prime breeding grounds for pests like termites, ants, and mice, which can spread to your home and cause costly damage to its wood and foundation. Stumps also attract fungi and diseases that can infect other healthy trees and plants in your yard. As a stump decays, it might sprout new, unwanted shoots. While removing a stump is an investment, it prevents these potential issues and enhances the safety, health, and appearance of your landscape.

In most cases, you should not use a pruning seal on trees after trimming. Applying a sealant can interfere with the tree's natural healing process, and it does not guarantee protection from pathogens. Instead of sealing the cut, the best practice is to support the tree's natural recovery by providing it with plenty of water and a dormant-style fertilizer. However, there are exceptions. Pruning seals may be recommended for very vulnerable species, like elm trees, in areas where dangerous diseases such as Dutch elm disease are prevalent. In these specific situations, the protection offered by a sealant can outweigh its downsides. For advice tailored to your situation, especially after cutting large branches, it is best to consult a local tree trimming professional.