Would horse manure kill a redwood?

It's highly unlikely that horse manure alone would kill a redwood tree. Here's why:

* Redwoods are tough: Redwood trees are incredibly resilient and have evolved to withstand harsh conditions, including wildfires and droughts. They're not easily killed by a single application of manure.

* Manure is a nutrient source: Horse manure, when composted properly, is a valuable source of nutrients for plants. It provides nitrogen, phosphorus, and potassium, all essential for healthy growth.

* Over-fertilization is a concern: While manure can be beneficial, too much of it can lead to over-fertilization, which can stress the tree and make it more susceptible to pests and diseases. However, a single application is unlikely to cause this issue.

Potential issues:

* Fresh manure: Fresh manure can be too strong for sensitive plants and may contain pathogens. It's best to compost it for at least six months before using it around trees.

* Improper application: If you pile manure directly against the trunk of the redwood, it can create a hot spot and damage the bark. Always apply manure in a ring around the base of the tree, several feet away from the trunk.

Conclusion:

It's highly unlikely that horse manure, especially in a single application, would kill a redwood. However, it's always best to practice good gardening practices and ensure the manure is composted and applied correctly to prevent any potential harm.