What are Nematodes?
- The word nematode is derived from Greek words- Nema meaning “thread” and oids meaning “resembling or forms”.
- Nematodes are also known by different names such as threadworms, roundworms, eelworms, and nema.
- Nematodes constitute the largest group of an animal kingdom comprising 80-90% of all multicellular animals.
- These organisms are basically aquatic but have adapted terrestrial habits.
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Introduction of nematode management
- Nematodes are omnipresent.
- Transmitted through a variety of methods.
- Irrigation water is the prime source infected composts soil.
- Control methods are needed to raise crops economically.
- Regulatory methods
- Cultural methods
1. Regulatory method
Quarantine / Exclusion
- This implies exclude the entry of a pest.
- Buy or grow transplants that are nematode-free.
- Use nematode-free soil or potting medium.
- Clean tools and equipment when changing areas of fields.
- Remove infected plant roots.
2. Cultural methods
- Keeping the nematode population under check especially when there are distinct host preferences.
- Susceptible crops should be grown once in a few years.
- Rotating them with non-host crops.
- Vegetables should not be grown in the same field repeatedly.
- Keep weeds in check.
Fallowing and Ploughing:
- Keeping the land fallow and deep ploughing reduce nematodes e.g. root-knot and others.
- Nematodes are sensitive to heat and drying action of the sun and the wind.
- So in hot and dry conditions following and ploughing are the best remedy of nematodes control.
Use of organic amendments:
- Green manure compost oil cakes have been found to Reduced Nematodes.
- These encourage the growth of natural enemies and decomposition products.
- Raising green crops also enhances the development of some predacious nematodes in the soil.
Use of resistant and tolerant varieties:
- The most practical and economical methods of controlling nematodes.
- Multi-resistant strains of plants to nematodes have been made.
- The main drawback sometimes is the development of resistant breaking nematodes which makes the process futile.
- Resistance has been mainly to root-knot nematode.
- Flooding can be adopted where there is an enormous availability of water.
- Under submerged conditions, anaerobic condition kills the nematodes by asphyxiation.
- Chemicals lethal to nematodes such as hydrogen sulfide and ammonia are released in the flooded conditions which kills nematodes.
- Certain crops like mustard, marigold, neem have chemicals or alkaloids as root exudates that repel or suppress the plant-parasitic nematodes.
- In marigold plants: alpha terthinyl and bithinyl compounds
- In mustard: alkyl isothiocyanate
- Such enemy plants can be grown along with the main crop or included in crop rotation.