Damage caused by pathogens
Dieback, resin bleed, cankers, discolouration, multileaders distortions or swellings, could all indicate the presence of a pathogen.
The occurrence of any of these symptoms in the absence of a discernable weather event or physical damage could indicate a pathogen.
Fungus fruiting on a poplar stem.
A good indication of serious wood decay. |
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Sirex wood wasp. Exit holes on radiata pine. |
Fruiting bodies such as brackets and mushrooms appearing on stems, powdery spores or any 'eruptions' from the bark could all indicate that a fungal agent is at work.
Damage caused by insects
Insect damage is often cryptic on live trees. Dieback for instance can be the result of branch borers but they are not visible until the branch is sectioned. Look for obvious holes, frass (borer dust), resin spots or weeping which might indicate a defensive response by the tree to attack.
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