The more common issues currently faced by trees are:
Oak Processionary Moth
This has recently arrived in the UK and poses a risk to both human and to a lesser degree, tree health. The caterpillar feeds on oak tree and their hairs can cause itching, rashes and less commonly sore throats, breathing difficulties and eye irritation.
The council is working in conjunction with the Forestry Commission to keep this pest under control.
Barnet has very few ash trees and as these are in urban areas, the impact of ash dieback is less serious that in rural areas. This disease overwinters in fallen leaves, so clearing leaves reduces the risk of infection.
For more information regarding fungi, pests or diseases visit the Forest Research website