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Are you confident your trees are structurally sound where it matters most?
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Get in touch with our Gristwood & Toms team
Request a quote from our certified arborists and ensure your site remains safe, compliant, and well cared for.
At Gristwood & Toms, we recognise that not all structural issues are visible from the outside. Decay and degradation may develop internally over time, affecting the structural integrity of a tree. Without accurate diagnostic insight, decisions to retain or remove may be made without the quantification – risking unnecessary intervention or unaddressed hazards.
Our Resistograph (Resi PD Arb) tree investigations provide the methodology to aid understanding of what’s happening beneath the surface.
Unlike PiCUS Tomography, which generates a cross-sectional ‘Tomogram’ at a fixed height, the Resistograph enables our consultants to test specific points – at height, into the structural roots, or anywhere throughout the stem – making it highly adaptable.
We recommend Resistograph testing when:
• A climbing inspection highlights decay or dysfunction at height• An air-lance investigation reveals potential root decay• Internal decay is suspected and cannot be confirmed visually• Cavities, historic pruning wounds or weak branch unions may require testing to assess residual wood strength• Clear evidence is required for risk management, planning, or legal compliance• There is a desire to retain a significant tree, but safety must be assured
At Gristwood & Toms, we support councils, developers, and commercial landowners with high-quality arboricultural reporting that enables safe, compliant, and well-informed site management. Every Resistograph tree assessment is carried out by qualified and experienced arboricultural consultants and aligned to latest industry standards – delivering clarity where it matters most.
Whether informing planning applications, development strategies, or risk management, our reporting is trusted for technical accuracy, consistency, and professional integrity, helping clients meet their obligations and manage tree stock responsibly.
Award winning and knowledgeable
Experienced in all aspects of tree and environmental health, our experienced consultants meet the highest recognised benchmarks in professional tree care and survey over 200,000 trees annually.
UK wide coverage, local expertise
With a commitment to minimal disruption, our nationwide team of tree surveyors offer expert, tailored services to maintain your site’s safety and compliance.
Rooted in sustainability
We utilise eco-friendly practices to ensure the long-term health and vitality of our green spaces. We prioritise environmentally responsible techniques that promote the sustainability of trees in urban and rural settings.
Certified for quality, safety and sustainability
With ISO 9001, ISO 14001, and ISO 45001 accreditations, we consistently deliver excellence in quality management, environmental responsibility, and occupational health and safety.
Leading tree management technology
We are recognised as the UK’s largest user of the Ezytreev tree data capture and management portal showcasing expertise in tree management technology.
ARB approved contractor status
As an Arboricultural Association ARB Approved Contractor we demonstrate industry-leading standards in arboriculture.
“I would like to commend Gristwood and Toms for their outstanding service in maintaining Enfield’s tree stock to the highest standards. Their professionalism, expertise, and reliability have been evident in all aspects of their work, from cyclical pruning and emergency callouts to tree planting and felling.”
Andy Robinson, Principal Arboricultural Officer, Enfield Borough Council
“Working with Gristwood and Toms has been a straightforward and efficient process. Their expert approach to arboricultural services ensures the safety of our highways. Clear communication and timely execution of projects, make them an asset to our operations. ”
Paul, Contract Manager, Ringway Infrastructure Services Ltd.
Delivering expert arboriculture and tree care services you can rely on.
Get in touch
Effortless
Your tree insights in 3 simple steps
Contact our expert team of arborists
Get in touch with our friendly team to discuss your needs, and we will guide you through the next steps.
Receive a site visit
Fill out the booking form and email it back to us, and we’ll schedule your survey and get started right away.
Receive a report
Once your survey is complete, we will compile your report and transfer the document to you in whichever format suits your needs.
Get the evidence you need to act with confidence
Gristwood & Toms has been a leader in UK arboriculture since 1974, delivering expert tree care with a strong focus on safety, compliance, and long-term landscape stewardship. As part of the Nurture Group, we support a broad client base, including local authorities, estates, infrastructure managers, and commercial landowners, with specialist consultancy and diagnostic services tailored to complex tree management challenges.
Whether you’re managing public spaces, development sites, or heritage landscapes, our testing gives you the evidence you need to protect both trees and people.
Delivered by our highly qualified consultants as part of a wider diagnostic programme, Resistograph testing helps our clients act with confidence – preserving what’s safe, addressing what’s not, and maintaining the integrity of trees across their sites.
From duty of care assessments to planning support, our team brings clarity to complex decisions, ensuring trees are preserved where possible and addressed responsibly where necessary.
