Kingdom Fungi | Rank Species | |
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Similar Rhabdocline pseudotsugae, Lophodermium, Mycosphaerella pini, Sphaeropsis blight, Pseudotsuga menziesii var glauca | ||
Phaeocryptopus gaeumannii or Swiss needle cast is a fungus that infects Douglas fir and causes yellowing of foliage and reduction in growth. It is endemic in western North American stands of Douglas fir, but was first discovered in trees planted Switzerland.
The classification of Phaeocryptopus gaeumannii within the Venturiaceae has been questioned, with molecular studies placing it in the Mycosphaerellaceae (Capnodiales), close to species of Mycosphaerella and Rasutoria, such as Rasutoria pseudotsugae and Rasutoria tsugae.
The fungus infects trees in the spring, and continues to develop over the following winter. The fungus causes yellowing (chlorosis) of the needles, with eventual necrosis and premature needle-drop. In some heavily diseased stands of trees, the only needles remaining are those of the current year, in which the disease has not yet had time to fully develop. The overall result for the infected tree is reduced growth.
The fungus is temperature dependent within the Douglas fir range, with the highest level of infection in the warmest part of the range. Growth reduction in the warm part of the range averages 35%.
