Current problems in a tree can be the result of an action several years ago. Using our example of the spruce tree, three year old needles falling off this year are often the result of a stress that happened three years ago. The fourth step in the work of a detective is the examination of the body, and it is the same with a tree. Are the roots fleshy and light coloured or are they brown or black. The discolouration or distortion of leaves is caused by factors such as drought, drowning, frost and winter-kill of roots, salt damage, chemicals, nutrient deficiencies, diseases and insects.
Healthy roots are white and fleshy.
Roots that are suffering from drought stress or chemical toxicity are brown, and black roots are a sign that the tree has either been drowned or is being attacked by root-rot organisms. Improper pruning- Fungal rot and cavities, sap weeping. Insects - girdling the trunk, feeding on decaying wood, foliage discolouration. By now insects and disease may have been ruled out as the cause of the decline of the tree. Generally insects feed either by chewing or sucking.