Cycles and importance of the larch budmoth
Pine trees are an integral part of the forest landscape across Switzerland. In recent years, they have come under increasing pressure, not least due to new fungal diseases that have been introduced from abroad. Needle and shoot diseases play a major role for pine health.
The Swiss Forest Protection Group has been documenting diseases affecting Swiss tree species since 1984. When the appearance (habitus) of an infested pine changes, the tree attracts attention. Needle and shoot diseases are clearly visible and thus easily change the appearance of the tree. Pines in particular are susceptible to many such diseases, also in comparison with other conifers such as Norway spruce (Picea abies) and silver fir (Abies alba).
This Fact sheet draws on the wealth of information gathered by the Swiss Forest Protection Group since 1984, and presents the pathogens of the most common needle and shoot diseases of pine trees in Switzerland. Physiological needle blight (also known as physiological needle cast), which is often confused with disease and therefore reported to the Swiss Forest Protection Group, is a natural process of needle ageing – a process undergone by all needles as time goes by. As it is not a disease, it does not appear in the list. However, it is described further on in the Fact sheet.
The first historical mention in Switzerland of a "disease" that turned extensive larch forests yellow-brown dates from 1820 in the municipality of Ardon in Valais (Coaz 1894). In the mid-20th century, when tourism in Switzerland slowly started picking up again after the Second World War, another larch budmoth outbreak was in full swing. Consequently, he tourism industry in the Engadine pushed for the application of DDT, considered a wondrous new insecticide at the time, to treat the unsightly forests.. In 1948, the pressure to apply insecticides set in motion a long-term study spanning six decades. In the course of this ongoing study, the larch moth changed in public and scientific perception from a mere pest to a ecosystem engineer and fascinating topic of study.