Tree paste

What is tree paste?

Tree paste — also called trunk coating — is a brushable mixture for tending the bark of fruit trees and woody plants. In biodynamic fruit growing it plays a part for the tree much like compost does for the soil: it tends and enlivens the bark, supports the living growth layer (the cambium) and closes the cracks in which pests could overwinter. Farms usually make it themselves, and it is in wide use.

Composition and recipe

A typical mixture is made of roughly equal parts clay, fine sand (or silica, also basalt powder) and fresh cow manure, stirred with rainwater to a brushable consistency. A portion of horn manure 500 is often added, and optionally horsetail tea, a little barrel compost or wood ash. Each ingredient brings something: the clay adhesion and minerals, the sand or silica the structure, the cow manure and horn manure the enlivening effect, the horsetail the protection against fungi.

Effect and application

The paste is applied with a brush to the trunk and main branches, usually in winter or after pruning. It acts on the cambium, the growth layer directly beneath the bark that is responsible for growth in girth and in the roots: the paste is meant to stimulate the tree’s life forces from outside, make it more resilient and encourage smooth, healthy bark. By closing cracks and rough patches it takes shelter away from overwintering pests. In fruit growing, coating the trunk is a traditional measure of care, which biodynamic practice supplements with the preparations.