"Dramatic turnaround" from soil amendments to landmark London tree

Soil amendment supplier Carbon Gold said its partnership with Apex Tree Surgeons to decompact and inject mycorrhizae-enriched biochar around the roots of an iconic south London oak is already showing positive results less than one year on.

Image: Barry Marsh (Public Domain 1.0)
Image: Barry Marsh (Public Domain 1.0)

The Bexley Charter Oak, which stands in the London borough's Danson Park. had been showing diminishing vitality and a reduced leaf area index, its leaves were turning pale, its huge canopy clearance was reducing, and the destructive beefsteak fungus (Fistulina hepatica) was starting to produce fruiting bodies.

Last November, Apex used a Geo-Injector to drill to a depth of 1.2m around the tree, then blasted 100psi of air around the root collar to the dripline, with the resulting pockets then filled with Carbon Gold’s enriched biochar.

Compared to this time last year, the Charter Oak’s crown is denser, its leaves are a darker shade of green, the branches are no longer drooping and all signs of retrenchment have been halted, despite the unprecedented heatwave and drought since spring," Carbon Gold said.

The borough's tree and woodland officer, Philip Louis added: "We weren’t expecting such a dramatic turnaround so quickly, especially with an organic product.

"We know from experience that chemical treatments and over-fertilisation can have a good short-term effect but actually worsen a trees health in the long run, so we were intrigued by the science behind enriched biochar and the geo-injector application process."

Thought to be over 200 years old, it takes its name from Bexley's Charter to become a Municipal Borough, which was presented underneath the Oak in 1937.

The tree now features on the borough’s coat of arms, and is one of Trees for Cities' 61 "Great Trees of London". It was featured in a report on tree health on BBC 1's Breakfast last Wednesday (29 August).

The companies are also asking the public to nominate five more ancient or veteran trees in decline that could benefit from the treatment, which they will provide for free. Nominations are to be made on the treerescue.org.uk site by 1 November.

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