Slug control

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Under snail control one understands methods of removing snails from the garden to prevent slugs. These methods can be biological , chemical or mechanical in nature.

The Spanish slug causes the greatest damage in the garden
The tiger snail eats other snails.
Cape snails are harmless in the garden

Eating habits of snails

Of about 250 species of land snails living in Germany, there are only about three species that cause major damage in the garden. The Spanish slug and the red slug cause the biggest problems . These are slugs .

Most snails are not pests worth mentioning, they mainly feed on dead plant parts, lichens and algae, some species also feed on their conspecifics and their clutches , e.g. B. the tiger snail , which is also found quite often. Snails play an important role in recycling waste within the ecosystem. Rib banded snails and snails addressed to no significant damage in the growing bed. There are contradicting data on whether Roman snails eat the clutches of other snails. It is noticeable, however, that one seldom finds a harmful slug within a larger Roman snail population.

Running ducks eat Spanish slugs.
Throttle forge with shattered snail shells

Biological and ecological means

In addition to fighting with natural enemies, there are other options for responding to damage caused by the Spanish slug. In organic farming , the focus is on biological and mechanical measures.

The culture management is important. Avoid ground covers and hiding places. An important preventive measure is to prepare the soil of the seedbed in such a way that the finest possible seedbed without cavities is created. This deprives the slugs of hiding places. Wilted and dead plants and plucked wild herbs should be left in the garden so that the snails can dispose of them and spare the fresh plants. The soil should be kept as dry as possible and the plants should be watered as precisely as possible.

The presence of predators can also reduce the snail population. The predators of snails include birds ( thrushes , crows , hawks, etc.), small mammals ( mice , hedgehogs , martens, etc.), insects, especially ground beetles and fireflies . Tiger snails should be left in the garden because they will eat other snails dead or alive. However, the problem is that most animals disdain the Spanish slug , the largest pest. Runner ducks , which can also be rented, help here .

The nematode species Phasmarhabditis hermaphrodita is a parasite of numerous species of snails and is also sold commercially for slug control under the trade name Nemaslug. However, their effect on the Spanish slug is only moderate. The effect is best on the wetting field snail . The native shell snails are not harmed by Phasmarhabditis hermaphroditis.

In the area of ​​allotment gardens, snail fences or so-called snail collars have proven their worth. Snails cannot crawl "upside down" and are prevented by this constructive feature of the "overhang to the outside".

Corten steel is said to be a difficult obstacle for snails to overcome. Corten steel contains less than 1% copper. However, this small amount is sufficient for the snail slime to oxidize the copper in the Corten steel. This creates an irritating substance for the snail that prevents the snail from crawling further. There are other ways to set up locks as well. Dried sawdust , water ditches, pointed and sharp objects such as broken glass, copper or low-voltage devices or a barrier made of fresh coffee powder (see below) or broken eggshells make it difficult for the animals or make it impossible for them to enter an appropriate area.

However, they only help against snails penetrating from the outside and not against animals or egg clutches that are already inside the protective device.

Beer and crevice traps

Nudibranch in a beer trap

The most famous home remedy for slugs is the so-called beer trap . It consists of a vessel filled with beer and embedded in the floor. The snails are attracted by the smell of the beer, fall into the liquid and drown. Although it can be used to destroy snails directly and inexpensively, it also attracts snails from the environment, which can then cause damage and lay eggs on their way to the trap. The disposal of the dead snails is also quite unpleasant.

Another disadvantage is that harmless and useful snails, such as. B. garden snails , Roman snails or glass snails, etc. are killed. Slit traps are often offered with a narrow gap that is impassable for the larger snails. These crevice traps are filled with molluscicides. The usual design is a trap with a collecting container for dead snails.

Chemical agents (molluscicides)

The commercially available agents known as slug pellets can be composed of various active ingredients. In general, chemical agents used to control snails are called molluscicides .

Slug pellets with the active ingredient iron (III) phosphate selectively fights slugs, including the protected Roman snail and other shell snail species, but is harmless to pets and hedgehogs. The use of slug pellets is therefore usually not recommended. For agricultural use to protect lettuce and rapeseed , positive study results are available, which show iron (III) phosphate as the agent of choice and advantageous over other chemical agents. In contrast to iron (III) phosphate, metaldehyde and methiocarb do not act selectively against snails. Metaldehyde causes the snails to secrete a lot of mucus, so that they perish when they become dehydrated. Methiocarb acts as a neurotoxin . The snails initially become hyperactive, then lose their muscle tone and die. The use of both active ingredients is controversial because they pollute the soil and water and can also damage birds and hedgehogs.

Caffeine in coffee powder is a potent poison for snails . Just sprinkling a solution containing 0.5% caffeine on it led to death after four days at the latest in laboratory tests. For fighting snails, filter coffee is more suitable than soluble coffee because of its higher caffeine content. Fertilizing with undiluted slurry or with fresh biogas compost harms the slugs.

literature

  • B. Speiser et al .: Slug Damage and Control of Slugs in Horticultural Crops. August 2001 (PDF file; 547 kB)
  • T. Briner, T. Frank: The palatability of 78 wildflower strip plants to the slug Arion lusitanicus. In: Annals of Applied Biology. 133/1998, pp. 123-133.
  • R. Albert: Slug control in horticulture. State Institute for Plant Protection, Stuttgart (PDF file; 1.74 MB)
  • H. Utschik: Changes in the population density of the Spanish slug (Arion lusitanicus) in a garden after control measures. In: Mitt. Zool. Ges. Braunau. 5/1987, pp. 43-47.
  • Vollrath Wiese: Germany's land snails. Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 .

Web links

Commons : Spanish slug  - collection of images, videos and audio files

Individual evidence

  1. ↑ Amazing things about snails. on: weichtiere.at
  2. ↑ The horror of the salad beds. Eating damage in the garden by the Spanish slug
  3. ↑ Colorful snails are no scare. on: nabu-rheinhessen.de
  4. ↑ W. Fischer, PL Reischütz: Basic remarks on the harmful snail problem . In: The soil culture. 49/1998, pp. 281-292.
  5. ↑ Land snails. on: weichtiere.at
  6. ^ E. Pianezzola, S. Roth, BA Hatteland: Predation by carabid beetles on the invasive slug Arion vulgaris in an agricultural semi-field experiment. In: Bulletin of Entomological Research. Volume 103, 2, 2013, 2013, pp. 225–232. doi: 10.1017 / S0007485312000569
  7. ↑ Happiness hangs by a thread. on: brandenburg.nabu.de
  8. ^ R. Rae, C. Verdun, PS Grewal, JF Robertson, MJ Wilson: Biological control of terrestrial molluscs using Phasmarhabditis hermaphrodita — progress and prospects. In: Pest Management Science. 63, 2007, pp. 1153-1164. doi: 10.1002 / ps.1424
  9. ↑ Bernhard Speiser (FiBL Research Institute for Organic Agriculture): Information sheet: Protecting organic cultures from snails. 3rd edition 2017 PDF download
  10. ^ W. Fischer et al.: The Spanish slug in Croatia. (PDF; 391 kB), In: Club Conchylia Informations. 31/1999, pp. 15-17.
  11. ↑ With coffee beans against snail damage. at: nabu.de , accessed on February 5, 2008.
  12. ↑ Species summary for Arion vulgaris. AnimalBase University of Göttingen, version from June 5, 2011.
  13. ↑ Species taxon summary - lusitanicus Mabille, 1868 described in Arion. AnimalBase University of Göttingen, version of March 31, 2006.
  14. ^ A b C. Hucklenbroich: Kahlfraß in German vegetable gardens. In: The world. July 8, 2007.
  15. ^ B. Speiser, C. Kistler: Field tests with a molluscicide containing iron phosphate. In: Crop Protection. 21/2002, pp. 389-394.
  16. ↑ Bait. at: www.schneckenprofi.de , accessed on February 6, 2008.
  17. ↑ Coffee makes voracious snails in the garden die of cardiac arrest. In: The world. June 27, 2002.
  18. ↑ B. Speiser: Fewer snails in a fine seedbed. (PDF; 989 kB), In: Schweizer Bauer. April 3, 2002.