Cunningham (1925) described Valsa dieback as common in stone fruit (Prunus spp.) throughout New Zeraland. It has been listed as the cause of serious dieback of apricots and peach trees in Central Otago. Dye (1952 & 1954a) showed that dieback in stonefruit in Central Otago was due initially to bacterial blast caused by Pseudomonas syringae van Hall. Fructifications on Valsa leucostoma are often found on wood killed by bacterial blast, as it quickly invades newly dead tissue: it will at times spread from the dead tissue to invade living wood. In apples (Malus sp.), and occassionally in stone fruit, Valsa invades tissues of trees debilitated by attack of a root rot fungus such as Phytophthora spp.