Pine cancer

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Pine cancer
Large witch's broom on the branch of a silver fir. The small dense yellow-green needles later form cup-shaped aecidia in two rows on the underside

Large witch's broom on the branch of a silver fir. The small dense yellow-green needles later form cup-shaped aecidia in two rows on the underside

Systematics
Subdivision : Pucciniomycotina
Class : Pucciniomycetes
Order : Rust mushrooms (Pucciniales)
Family : Pucciniastraceae
Genre : Melampsorella
Type : Pine cancer
Scientific name
Melampsorella caryophyllacearum
( DC. ) J. Schröt.

Fir cancer is a common name for the rust fungus Melampsorella caryophyllacearum on fir trees . Infected trees form witch brooms , which are clearly visible as growth anomalies on branches and twigs. When the infection spreads to the main trunk, a lump-like thickening of the trunk forms, which grows from year to year, and which is then called " tree cancer ", while the tree itself is called "wheel fir". In phytopathology, “cancer” is not synonymous with uncontrolled tissue growth.

Course of disease

The rust fungus causing the disease shows an obligatory change of host . While the firs act as haplont hosts, carnations (Caryophyllaceae) such as chickweed and hornwort serve as dikaryote hosts , which is why the fungus was given the scientific name Melampsorella caryophyllacearum . The infection of a fir happens in May and June by a basidiospore. The fungus can then be found systematically in the tree over the long term. In the following year, hormonally induced, upright, densely branched shoots with narrow, small yellowish-green soft needles appear on the infected branch on a thickened section (witch's broom). In summer, orange-yellowish spore beds of the pathogen appear on the underside of the needles, which then germinate on the dikaryote host. The needles of the witch's broom fall off as early as autumn, but aecidia are formed again on the needles of the following year. So there are only needles of one year on witch brooms. The massive occurrence of witch brooms can occasionally cause the death of a fir tree because the needles on them are sensitive to frost and therefore occasionally die off prematurely.

If the cancer occurs on the trunk and it gradually thickens in sections, the bark becomes increasingly cracked and more permeable to other, often fungal pathogens such as the fir sponge ( Phellinus hartgii ), which causes white rot (secondary infection). The fir cancer thus represents a strain evaluation. In Central Europe 2 to 15% of all firs are infected by Melampsorella caryophyllacearum .

Not only silver firs are infected as haplont hosts, but also Nordmann , noble , Colorado , magnificent and Veitch firs . Damp edaphic and climatic conditions have a beneficial effect .

Countermeasures

From a forestry point of view, the early removal of the sick individuals is recommended. Witch's brooms carry the risk of serving as a source of infection for many years to maintain host change. Fir trees infected on the trunk are devalued by the fungus. Sometimes it is advisable to control the intermediate hosts and to remove the diseased parts of the plant from still young crops.

  • Melampsorella caryophyllacearum (branches)

  • Melampsorella caryophyllacearum (branches)

  • Melampsorella caryophyllacearum (branches)

  • Melampsorella caryophyllacearum (branches)

  • Melampsorella caryophyllacearum (branches)

  • Melampsorella caryophyllacearum (young silver fir )

  • Melampsorella caryophyllacearum (strain)

literature

  • Fritz Schwerdtfeger : The forest diseases. Textbook of forest pathology and forest protection. Paul Parey, Hamburg and Berlin 1981, ISBN 3-490-09116-7
  • Günter Hartmann, Franz Nienhaus and Heinz Butin : Color Atlas Forest Damage . Diagnosis of tree diseases. 2nd revised and expanded edition. Ulmer, Stuttgart 1995, ISBN 3-8001-3351-2

Individual evidence

  1. ^ TU Munich: Tannenkrebs ( Memento from September 29, 2007 in the Internet Archive ), accessed on May 25, 2008
  2. ↑ Federal Research and Training Center for Forests, Natural Hazards and Landscape: Diseases and pests in Christmas tree cultures - Fir - shoot damage - Fir cancer , accessed on May 25, 2008.

Web links

Commons : Pine Shrimp ( Melampsorella caryophyllacearum )  - Collection of images, videos and audio files