Q: If your neighbor has a tree in his yard and one of his branches is on your property is it your responsibility.

A: If a branch from your neighbor's tree extends onto your property, the responsibility for maintaining that branch is a bit of a legal gray area and can vary depending on local laws and regulations. In general, you have the right to trim the branch back to the property line, but you should not cause damage to the overall health of the tree.

Regarding your specific question about spraying bug spray on the branch that extends onto your property:

1. If the bug spray you used was appropriate for its intended purpose and applied correctly, you likely would not be held liable for the tree's death, as you were treating a branch on your property.

2. However, if you used an excessive amount of bug spray or a product not intended for use on plants, and this action led to the death of the tree, you could potentially be held liable for damages.

3. In some jurisdictions, if the tree is considered a "boundary tree" (i.e., the trunk is growing on both properties), you might be required to consult with your neighbor before taking any action that could harm the tree.

To avoid potential legal issues and maintain good relations with your neighbor, it's best to discuss the situation with them before taking any action. If you cannot resolve the matter amicably, consult with a local arborist or a lawyer specializing in tree law or property disputes to understand your rights and responsibilities according to your local laws.