Tree paste after Maria Thun: bark care for fruit trees

Tree paste — also called tree wash — plays a similar role for a fruit tree as compost does for the soil: it cares for and enlivens the bark, stimulates the growth layer and seals cracks in which pests overwinter. In biodynamic fruit growing, as it goes back to Maria Thun among others, it is a common, home-made care measure on the farm. This article shows what it consists of and how to apply it. The basics are also in the glossary entry Tree paste.

Composition

The core is a spreadable mixture of roughly equal parts clay, fine sand or rock dust (basalt dust also works) and fresh cow manure, mixed with rainwater. Each ingredient brings something: the clay provides adhesion and minerals, the sand or rock dust structure, the cow manure the enlivening effect. The paste is often supplemented with a portion of horn manure and a horsetail extract, which supports protection against fungi through its silica. Depending on the farm's recipe, other ingredients are added.

The exact recipe is not strictly fixed — it varies from farm to farm. What matters is the consistency: rather thick, like quark, for brushing on, thinner for spraying. Too thick and the paste cracks as it dries; too thin and it runs off.

The right time

Tree paste is applied in the winter half of the year, ideally after leaf fall and before the sap rises in spring, and following major pruning. The bark should be dry and not frozen; loose bark is brushed off beforehand. The paste adheres poorly to wet, frozen or sun-heated trunks.

Applying

Using a paintbrush or brush, the paste is applied to the trunk and main branches — over a large area, so that cracks and rough patches are reached too. It acts on the cambium, the living growth layer directly beneath the bark: the care is meant to stimulate the tree's life forces from the outside, make it more resilient and promote smooth, healthy bark. By sealing cracks, it takes away shelter from overwintering pests.

Frequently asked questions

What is tree paste made of?

Clay, fine sand or rock dust and fresh cow manure, mixed with rainwater — often supplemented with horn manure and a horsetail extract. The exact mixture is not strictly prescribed.

When is tree paste applied?

In the winter half of the year after leaf fall and before the sap rises, and after major pruning, on dry, unfrozen bark.

What does tree paste do?

It cares for the bark, stimulates the cambium, promotes healthy bark and seals cracks in which pests overwinter.