Research continued during 1995 on a lethal Phytophthora disease of alder first recognised in 1993. Various steps were taken to improve knowledge of disease distribution and in consequence a more complete picture has been obtained. The disease is now known to be widespread through much of England and Wales. However, it is not known to be present in Scotland, parts of northern England and the extreme south-western peninsula. Survey data from rivers more than 8m wide indicate that although the increase in disease between 1994 and 1995 was relatively small, more than 20 000 trees are severely affected and up to 11 000 have died. The history and possible origin of the disease is discussed, together with questions of infection biology and control. Landowners should consider a temporary cessation in the planting of alder.
443.3 (Krankheiten in späteren Wachstumsstadien) 176.1 (Dicotyledoneae [Siehe Anhang D]) [410] (Vereinigtes Königreich von Grossbritannien und Nordirland)
