Ms Geraldine O'Sullivan:

It depends again on the health of the trees, but it can take a while to see that. It is not going to be immediate. Obviously, it has to burrow in. It is ash dieback, so it can take a while for it to be visible. If the trees are under stress, it will show quicker. It can show quicker in older trees than in younger ones. Again, trees may have it and then they have to build the numbers within it as well, so it can take a while to show. I am not sure exactly, but it can be seen that once it happens, it can move very rapidly within the forest if there are numbers and if there is a weakened defence. In healthy trees, normally, the resin, particularly in the spruce, does act as a kind of barrier to it. Again, however, if there is drought or flooding or any stress on the tree, that is where it is likely to go. It is dieback; it is slow. It is not immediate. It can take time depending on the health of the forest.