Looking after your trees: Signs of stress, what to do, and when to call the experts

Kenton Smith and Tony Kirkham, author of the Haynes guide Trees, give their tips on making sure the trees in your garden stay healthy.

Stress is an increasing challenge for people living in the modern world, especially for those in urban areas. There is also a growing body of research that highlights the importance of trees and nature in reducing our stress as well as the many other benefits trees provide.

However, trees themselves also get stressed, especially in our towns and cities, which is where they can often have the most impact on our health and wellbeing. Trees are often seen as strong resilient organisms, but they are also very vulnerable.

Often, the signs of stress in trees go undetected until it is too late, the tree becomes diseased and enters a spiral of ongoing decline.

How trees stay healthy

A healthy, stress free tree is much more likely to be able to resist attack from any pest and disease. This is because it will be performing at its optimum level and will be producing surplus energy, which it can store in reserve. These reserves can then be used to heal the tree by growing over and around lost or damaged areas or by strengthening its tissues to resist attack.

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As with humans, ill health in trees is often associated with some form of stress on the tree’s system. Tree health can be very difficult to determine because, in the early stages, there are often no visible signs that a tree is actually under stress. By the time visible signs appear, such as dying branches or the presence of fungal fruiting bodies, a significant amount of damage could have already occurred.

What trees need, and the early signs of trouble

Incidental and regular checks on your tree need not be exhaustive and may help you notice problems as they appear. An arboriculturist can then be consulted to provide a diagnosis and treatment if required.

Essentially, trees need access to light, a soil that is not compacted, key nutrients, water and finally the space to grow into (above and below ground). Anything that impedes these will of course put stress on the tree’s system.

By understanding how trees grow and what they need to grow, the potential for stress in trees can be reliably deduced from observing the immediate environment, as this will certainly be impacting on the tree’s health.

Furthermore, stressed trees will often come into leaf a little later than those that are healthy, and the leaves will often be paler in comparison, so surrounding trees can also be a good guide.

Credit: ‘Trees: Owners’ Workshop Manual’ by Kenton Rogers and Tony Kirkham

Young trees, old trees

In smaller, newly-planted trees health issues are sometimes easier to identify and treat by the homeowner. Newly planted trees will have been stressed to some degree by the planting process and are unlikely to have reserves as they will be putting all their energy into establishing their growth. Therefore health issues are likely to be more acute in younger, more vulnerable trees.

In larger, older and veteran trees health issues may well be more complex and professional opinion from a qualified arboriculturist may need to be sought to diagnose any signs of ill health and the implications for management of the tree.

Credit: 'Trees: Owners' Workshop Manual' by Kenton Rogers and Tony Kirkham

Credit: ‘Trees: Owners’ Workshop Manual’ by Kenton Rogers and Tony Kirkham

Tell-tale signs of problems

Holes and cavities in the tree may not necessarily be a sign of stress, but they are an indicator of previous damage that may need the attention of an arboriculturist.

Diagnosing the reasons behind the stress or ill health in the tree may therefore be complex but, in the first instance, before inspecting the tree (or arranging for a professional to do so), a great deal of information can be ascertained from looking at the surroundings in which the tree is located.

Often the constraints on the tree posed by physical features will lead to a stress that can leave the tree more prone to a secondary attack by pests and disease. So even if a given pest or disease is identified and treated there may be a further underlying cause that is attributable to the site conditions.

A tree diagnosis checklist

Recognising the physical features around the tree may help to answer this question and professional advice can then be sought to confirm the cause of stress and the best course of treatment to take. Some of the main causes of potential site-induced stress are:

  • Lack of available soil rooting volume
  • Lack of water
  • Waterlogged soil
  • Weed competition
  • Soil Compaction
  • Low Light
  • Extremes of temperature

And finally, how to find a good tree surgeon

Credit: 'Trees: Owners' Workshop Manual' by Kenton Rogers and Tony Kirkham

Credit: ‘Trees: Owners’ Workshop Manual’ by Kenton Rogers and Tony Kirkham

In the UK the Arboricultural Association maintains an online directory of quality-assured tree surgery businesses and consultants. They are regularly assessed for their health and safety procedures, office and business practices, including customer care, as well as their quality of tree work. They will display either the ‘AA approved Contractor’ or ‘AA registered Consultant’ logo.

Check the contractor’s approval is current on the website at trees.org.uk/Find-a-professional.

Other arborists may be equally competent even if they do not subscribe to this scheme but you should take more care to make sure that they are suitable trained and insured.

This advice comes from ‘Trees’ published in March of this year at £22.99 by Haynes and available from www.haynes.com.