Methods to control plant nematodes

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.

Methods

• 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

Crop rotation

• 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

• 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.

Antagonistic crops

• 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.

References

1. https://www.intechopen.com/books/nematology-concepts-diagnosis-and-control/the-impact-of-plant-parasitic-nematodes-on-agriculture-and-methods-of-control
2. https://www.nap.edu/catalog/18682/control-of-plant-parasitic-nematodes
3. http://agropedia.iitk.ac.in/content/management-plant-parasitic-nematodes
4. https://link.springer.com/chapter/10.1007/978-1-4020-6063-2_4

Methods to control plant nematodes