Dieback and death of larch caused by Ceratocystis laricicola sp. nov. following attack by Ips cembrae.
The new species is described. Circumstantial and experimental evidence is presented which suggests that the bark beetle Ips cembrae acts as a vector for C. laricicola which it introduces into larches during breeding attacks. The fungus kills bark and cambium, and invades the sapwood causing the formation of blue stain areas surrounded by dry wood. Multiple inoculations resulting from numerous beetle attacks may totally disrupt conduction causing dieback and death of whole trees. Attacks seem to be frequently associated with drought and other forms of stress. Trees damaged by I. cembrae and C. laricicola may be attacked subsequently by the woodwasp Urocerus gigas which introduces a sapwood decay fungus, Amylostereum chailletii [Stereum chailletii]. This is the first record of an association between I. cembrae and a Ceratocystis sp. and the first record of dieback in larch caused by I. cembrae and C. laricicola. I. cembrae was introduced into Britain from mainland Europe and it is suggested that a similar association may occur there.