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Beneficial individuals are not only in organic gardens on the rise. As an opponent of the numerous insect pests, they provide a biological balance in the garden. Beneficial natural enemies of garden pests, which eliminate the pests without the use of chemicals. These include nematodes.
What are nematodes?
Nematodes are invertebrate worms. They are under one millimeter in size and can be easily recognized with a magnifying glass. There are around 20,000 different types of nematodes. Some species are useful. They settle in animal organisms and destroy them. They are therefore referred to as beneficials. Other species cause disease symptoms in humans, animals and plants. These are not used for plant protection.
Use of nematodes
The beneficials are characterized by a natural eradication of pests. This is also how the use of nematodes works. Pests are completely battled biologically. There are no residues left in the soil or in the plants. There are no side effects such as waiting times or resistance. The treated areas are always available.
Which pests are fought with nematodes?
Nematodes have a very wide range of uses. You decimate:
- codling moth
- Banana cane borers
- dung beetles
- Garden chafer
- fungus gnats
- Tipula paludosa
- HM nematodes (Heterorhabditis bacteriophora)
- SC Nematodes (Steinernema carpocapsae)
- SF nematodes (Steinernema feltiae)
- PH nematodes (Phasmarhabditis hermaphrodita)
Development cycle nematodes
A life cycle of beneficial organisms consists of several stages. The first stage consists of the egg. In the second stage, a larva develops in the host animal. In the third stage, the larvae independently search for host animals. For the control of garden pests nematodes are used in the third stage of development. The nematodes enter the host animal via body orifices and release a bacterium, Xenorhabdus spec. The bacterium prevents the decay of the host animal and helps the nematodes in overcoming the immune system of the affected body. An infested insect, such as a weevil larvae, turns red-brown. The nematodes multiply until the host animal is completely consumed. In the host animal, the nematodes reach the fourth stage of development. You become a reproductive female and male. Each female can lay over 1500 eggs. One cycle lasts between one week and three weeks before the nematodes seek a new host animal.
Use of nematodes
The use of nematodes is always over a longer period during the development cycle of insect pests. It can last for several months, a quarter or even years. So, weeping buttercups are successfully fought between April and the beginning of July. Against overwintering larvae of codling worms are applied after the harvest of apples. In the greenhouse, nematodes can be used all year round. As with field maize beetles, success only occurs if the young larvae are fought over three years. One square meter is expected to yield around 500,000 nematodes. Some nematodes, such as the Heterorhabditis bacteriophora, specifically search for their host animals. Others, like the Steinernema carpocapsae, wait quietly until a host animal comes over. Steinernema feltiae pursues both strategies to find a host animal.
Spreading the beneficials
The trade delivers nematodes in a resting state. The powder available in plastic bags contains the nematodes and clay minerals. If a pack has broken in, it must be used within a few days as the nematodes dry out. Moisture is also important when spreading. An advantage is a cloudy sky or fog, as UV radiation can damage the roundworms. The soil to be treated must be moist. Waterlogging does not tolerate the beneficial effects. The spreading is also dependent on the soil temperature. It varies from species to species. Nematodes are used with a lot of moisture as a spray, in the watering can, as drip irrigation and with pumps. The powder can be combined with fertilizers, insecticides and fungicides. The treated soil must not dry out for two to three weeks. Tip: Remove all strainers in the nematode mixing vessels. Stir the liquid as the nematodes settle in the vessel. The pressure of pumps must not exceed 4 bar.The pouring opening must be larger than 1 mm. Empty the containers with the mixture completely.
advantages and disadvantages
Nematodes have no side effects. Greenhouses can be committed at any time. The application of the beneficials is easy. Nematodes are relatively insensitive to chemical pesticides. A disadvantage is the short shelf life and the storage temperature at four to six degrees Celsius. An opened package must be consumed immediately. Each packaging has an expiry date printed on it.
frequently asked Questions
- Are nematodes harmful? - The species used do not harm humans, animals, plants or microorganisms in the soil.
- Are there any residues? - Nematodes can be applied completely residue-free. There are no residues in fruits and vegetables. Waiting times are not necessary. Nematodes die at temperatures above 35° C.
- How are nematodes spread? - The powder with the beneficials is diluted in water.
- How long is the duration of use? - The use of nematodes adapts to the development cycle of insect pests.
Nematodes are roundworms and one of the most species-rich strains of the animal kingdom. Most are small, white to colorless, filamentous worms, which live in moist media. Without a magnifying glass, they are hardly recognizable. Nematodes may be sedentary or roaming.
Nematodes as beneficials
Nematodes are increasingly used as beneficials against snails, Dickmaulrüßler and other plant pests. They fight with the help of bacteria that carry them, pests and their larvae. Many also participate in the formation of humus and make themselves so useful. They live in the soil and feed on algae, bacteria and fungi.
Nematodes as pests
- But you can also do damage. When they infect vegetables and ornamental plants, they cause spots and bile. Most nematodes prefer plants that promote their reproduction.
- There are nematodes that sting the plant tissue with their mouth sting. They give off saliva secretions. This leads to a change in the tissue, usually in vegetables. Sometimes it helps to change the cultivated area. Roses, strawberries, potatoes and tomatoes are particularly frequently attacked. Leaves and stems bend, are curled. With heavy infestation they can die together with the roots.
- By sucking bacteria and viruses can be transmitted. This causes even greater damage.
- Infested plants must be destroyed. They must not be composted. Before planting, make a green manure with chamomile and borage. Excessive nitrogen fertilization should be avoided.
- If there is a risk of nematode, you can sow Tagetes nana, chamomile, calendula and coneflower over a large area. If tomatoes are affected, you can put Zinien in between.
- Kornrade excretes toxic saponins that kill the nematodes.
- In greenhouses, it usually only helps to replace the entire soil. Garden tools must be well cleaned and disinfected.
- Feathers, fungi, predatory mites and predatory nematodes are natural enemies of nematodes. Mycorrhizal fungi can be used preventively to build a defense system on crops in the soil.
- Plant protection products used against nematodes are called nematocides.
- Nematodes can also affect humans. The infections are usually harmless. The most common is a strong itching in the area of the anus. Treated with drugs against worms. You should pay more attention to hygiene.