I recently paid a visit to Vienna and while driving through the countryside I noticed that all the horse chestnuts had turned prematurely brown and the trees generally had a rundown appearance. My first thoughts were that some form of Dutch elm disease was responsible but there were no perforations in the bark. On enquiry I found that a scientist had allowed some form of moth to escape some years ago, and that they were causing the trouble, which applied to all the horse chestnut trees in Austria. The symptoms are a margin of brown around the edge of each leaf. Could you identify this moth?
David Power, Drimaagh, Dublin 12.
I have not heard of the moth you mention. Normal moth/caterpillar damage to trees means that the leaves are eaten, but a moth might introduce a fun gal disease, perhaps by feeding on the secretions of the flowers or buds.
However, the margin of brown around each lead is similar to the effects of potash deficiency but how is such a deficiency general throughout the country? A forester friend says that potash in Ireland is carried inland by sea winds and only areas in the centre of the country suffer from a deficiency. Perhaps a continental country like Austria might not get enough potash in certain weather cycles.
Visiting Glendalough last July on a bright afternoon, we noticed silver tracery all up the side of the round tower. Could we be right in thinking that snails don't suffer from vertigo?
Katie & Patrick Davey, and Alessina Kilkelly, Killiney, Co. Dublin.
Yes. And they won't come unstuck either because of sneezing or St Vitus's dance.