A POTENTIALLY deadly fungal disease is spreading quickly through alder trees and the Environment Agency says it has reached Yorkshire.

The fungus is called phytophthora and since 1996 it has become a real problem; the recent rain over the past three years has reduced the effect but if we get a warm summer, we need to keep an eye on our alders.

A sure sign of the disease is black smudges which appear in the bark. Not all trees seem to be affected, which suggest some degree of immunity.

The Environment Agency has conducted a thorough survey and along with the expertise from the Forestry Commission a code of practice has been devised.

All who enter a river or even walk along the riverside should:

1. Clean off all footwear, equipment or machinery before moving upstream to another stretch of water.

2. Whenever possible, delay moving from one catchment to another, as the fungal spores only live for a few days.

3. Avoid transferring any river water between watercourses or from an upstream area.

4. Ensure fishing tackle is thoroughly dried before moving to another water.

All this seems to show that the alder disease suggests that the fungal spores multiply more easily in drought and low flow conditions.