It is not the purpose of this chapter to describe all the diseases that can affect alder. Rather, an attempt has been made to collate and evaluate information on diseases in which the symptoms have some similarity to those found in the Phytophthora disease. As described by Sreito (Chapter 4), the key symptom is the lesion in the inner bark of the stem; a lesion that is often marked externally by the presence of a tarry or rusty exudation. In severely affected trees, the foliage is small, sparse and often yellowish. Mortality usually follows, although recovery is known to occur, with or without the death of some branches. However, not all the symptoms are always evident. In particular, tarry spots may be absent and basal lesions difficult to find. This review is intended to proviede a useful resource for current and future studies in alder pathology. It could also indicate if any former episodes of crown damage and death represented unrecognised outbreaks of the Phytophthora disease. That this might be possible is illustrated by experience in Austria. Diseased A. glutinosa was investigated on the river Thaya and its tributaries near the border with Czech Republic in 1985-1987. It was concluded that the damage was due to abnormal changes of river water levels, several bark-invading and wood-decay fungi and perhaps, frost (revords from Federal Forest Research Centre 1948-1999). During the first half of the 1990s the disease classic symptoms of the Phytophthora disease were recognised and the presence of the fungus was confirmed (Cech and Brandstetter, 1999).
