Serpula lacrymans

Fruiting body of a dry rot

The genuine dry rot ( Serpula Lacrymans ) is a wood-destroying fungus. In addition to the Brown cellar sponge ( Coniophora puteana ) it is a main cause of damage due to dry rot in buildings. The dry rot infects preferred wood used and needs a moist and not too cool environment for growth. As often Guttationströpfchen can be seen on him, he is often called tear Santander dry rot. The dry rot is considered the most dangerous building destroyers.

Way of life

The dry rot is a wood-destroying fungus and a representative of the Hausfäulepilze with the highest potential risk to buildings. In Central Europe, the fungus causes about 32 % of fungal damage to buildings. Like all Hausfäulepilze including dry rot to brown rot fungi and is therefore dependent on cellulosic materials. Besides wood, the fungus also applies to other organic materials such as, inter alia, Textiles, paper, chipboard, straw and reeds good growth conditions.

The dry rot is exposed to many different growth factors. Favourable conditions for the beginning of the growth he finds at 35 to 60% wood moisture. The widespread opinion, the dry rot can infect wood with humidity levels below 20% by zoom carries the water required for this purpose in its strands is not occupied. However, as is the moisture content of wooden constructions, especially in residential buildings between 10 and 15%, an acceptable moisture for the fungus occurs only under special conditions. For this purpose, inter alia, include the condensation points, for example, Beamed heads or defects ( leaks).

In addition to the substrate moisture and the temperature plays an important role for fungal growth. The temperature optimum of the fungus is 18 ° to 22 ° C. About a temperature of 26 ° C, the fungus its physiological activity but suddenly a.

At very vital and large-area growth separates the mushroom water drops from ( Guttationstropfen ). These " tears " (Latin lacrima ) were eponymous be, but also made from other types of fungi. If large Mycelgeflechte exposed and thus exposed to light and fresh air moving, the fungus can develop relatively fast spontaneous fruiting bodies. However, even die for to strong drafts the mycelium.

The high potential risk posed by the dry rot, derives from its special abilities: The fungus is in fact able to grow or to penetrate inorganic material. Thus, the mycelia of the fungus masonry, plaster, dumped, among other things may by or under grow. Based on these observations, this fungus is also often referred to as " sponge wall " means.

Oak wood is not a good substrate for the fungus, it is more likely to grow. The tannic acid and other ingredients act as natural fungicides. However, it is (rarely ) before that (covert soffits ) form of oak wood stairs fruiting bodies.

Of damage

The dry rot fungus is a typical surface a well-developed Oberflächenmycel. An infestation of wood is usually accompanied by an intense, coarsely diced brown rot. In advanced infestation, the wood is a cube broken and can not be pushed by hand. Characteristic are the brownish and weißrandigen patty-shaped fruiting bodies, which are coated with rust-brown hymenium. The fruiting bodies are often visible on the growing substrate and are characterized by a sharply defined edge of the growth Oberflächenmycels with up to 1 cm thick white-gray strands from. With the help of Mycelstränge the fungus is to be transported in a position to water over long distances. In rooms with low air circulation and high humidity, such as, inter alia, Basements, the fungus can form an extremely bulky aerial mycelium. Another feature of the immense Braunfäulepilzes spore production.

The first perception of the fungus on surfaces may be headed into cavities years of growth.

Damage control and prevention

An attack by the true dry rot can be recognized by its typical mycelia strands and fruiting bodies. The aerial mycelium is white, translucent, even on masonry. If in doubt, can be a useful molecular or microscopic examination.

Infestation with Genuine dry rot is reportable in some states. He is a heavy tree Angel according to BGB. According to DIN 68800, Part 4 (timber; control measures against wood-destroying fungi and insects) are to determine the infestation and the extent of infestation by an expert ( Making a wood protection technical investigation report). In general, to be developed by such expert and rehabilitation proposals.

The fight must be carried out necessarily by an authorized specialist companies ( Qualified ). The DIN 68800-4 in conjunction with the WTA data sheet The dry rot is remediation recommendations. The monitoring of this work should also be done by an expert.

The dry rot is by far the most difficult -to-control wood-destroying fungus, because it can also affect relatively dry wood and masonry by growing. It is disputed whether draft interrupts growth. The fungus needs a certain, albeit low moisture supply, but then it grows sometimes very fast, usually unrecognized and unnoticed. The fungal residues can persist for many decades and in the dry state. The rehabilitation must be accompanied by a draining of masonry and wood construction and can therefore be extensive. So often infested wood parts must be cut well in the longitudinal axis at 1 m safety distance from the last recognizable affection. In advanced infection often remains only the replacement of the entire wooden structure.

At the beginning of a sponge rehabilitation is the identification of the pathogen. Is not clearly belonging, must always be proceeded as if a dry rot infestation: Here, with a safety distance of 1 m infested wooden parts removed. In beds, a safety distance of 1.5 m is observed. Furthermore, must be removed infested masonry, beds etc.. To also remove last Mycelreste, the masonry is often recommended abzuflammen. Furthermore, it is necessary to find the cause of the source and to remove moisture to prevent a re- fungal attack. Is it guaranteed by structural measures that the infested wood and the walls are dry and stay dry in the future, the renovation costs can also be reduced under the guidance of an expert in a particular case. Without moisture, the dry rot one 's metabolism and also destroys no more wood. But he remains in the component and is also decades later quickly active in the presence of moisture again.

In order to contain the risk of carryover, a professional and careful disposal of the removed pieces of wood and masonry parts is necessary. In addition, it is necessary to leave the area after the renovation dry well and treat the damaged areas with suitable chemical protection agents. Here, the masonry can be painted with a sponge blocking agent, or the protection agent is introduced in the context of a borehole impregnation. Neueingebautes wood may need to be in accordance with DIN 68800, part 3 be impregnated preventively.

A disadvantage is the high cost turn out in the renovation of a dry rot infestation by the professional removal and disposal of material removed. In addition, a variety of wood and masonry needs to be replaced or treated to prevent reinfestation.

For the protection of cultural and historical buildings is also frequently used the hot air method in the context of rehabilitation. This method is based on the fungus dies at temperatures above 50 ° C. However, this process meets in large rooms or on thick masonry to its limits, since then often the corresponding Letaltemperatur is not reached.

The dry rot was chosen in 2004 by the German Society for Mycology for fungus of the year, to refer to his often underestimated economic importance.