There is some good evidence that some individuals demonstrate a good level of resistance to the disease and that this resistance is heritable. There is also some reasonably good evidence that this resitance is related to the time of leaf fall. Those of you with a good number of Ash in your woodlands will probably have noticed that some individuals will have lost all their leaves before some other trees have shed many at all. It seems that what the trees showing resistance have in common is that they are all trees that shed their leaves early.
I think it's now very unlikely that this disease can be contained, let alone erradicated in the U.K., and I think it unlikely, based on the pattern of spread in Europe, that it will take much longer than a decade or so for the majority of our ash trees to become infected. It might be interesting - and potentially useful in helping develop particularly resistant strains to breed from and repopulate ash into our woodlands - to mark those ash trees on your land which lost their leaves early now.
There is a poorly tested hypothesis about why those trees that their shed leaves early might have a higher resistance - if anyone's interested just ask - but it is really only a suggestion as to the cause of the link and whether it's right or wrong doesn't detract from the pattern of resistance being associated with early leaf drop. Now is the best time of year to reccord the differences in leaf drop on your trees - perhaps if you're doing any thinning and you have to choose between ash trees, it would be worth knowing if one was a particularly early leaf dropper and thin to favour that one.
