Resistograph

This instrument uses a very fine micro-drill to penetrate a tree’s tissue, measuring resistance to the probe.  Sound wood provides greater resistance than decayed wood, so we can interpret the graph trace produced by the Resistograph to establish the tree’s internal condition.  The Resistograph is particularly useful for testing buttress roots or for aerial examination of limbs within a tree’s crown.  It is also sufficiently sensitive that it can measure individual annual growth rings.

We use the latest IML Resi-PD microdrill from Sorbus International Limited.