Indian root lesion nematode

Pratylenchus indicus, commonly known as the Indian root lesion nematode, is a microscopic worm belonging to the family Pratylenchidae. It is classified as a migratory endoparasite.

Adult nematodes are slender and range from 0.4 mm to 0.6 mm in length. They possess a robust stylet used to pierce plant cell walls and extract nutrients from the root cortex.

The life cycle encompasses eggs, four juvenile stages, and adults. Reproduction is efficient, often occurring within the root tissues, allowing populations to escalate rapidly under favorable conditions.

As migratory endoparasites, they move freely between soil and root tissues. This mobility allows them to search for fresh host sites and survive in various soil types.

These nematodes have high plasticity, allowing them to adapt to diverse agricultural environments, which makes them persistent pests in rice-growing regions.

Rice (Oryza sativa) is the primary host for Pratylenchus indicus. The nematode invades the root system, causing cellular disruption and restricting the plant's ability to uptake water.

The feeding process creates necrotic lesions on the roots. These wounds serve as entry points for various soil-borne fungi and bacteria, which can lead to complex root rot diseases.

Besides rice, the nematode can parasitize various weeds and rotational crops, ensuring its survival even when the primary host is absent.

Heavy infestation severely compromises the root structure, leading to stunted shoot growth, nutrient deficiencies, and significant yield losses in agricultural production.

The reduction in root mass limits the plant's overall vigor, making it less resilient to drought, salinity, and other environmental stressors common in rice paddies.

Plants infested with Pratylenchus indicus often show patchy growth, with visible areas of stunting and uneven development across the field.

Visible symptoms include yellowing (chlorosis) of the leaves, which often mimics nutrient deficiency symptoms like nitrogen starvation.

Below the surface, the root system shows browning and necrotic lesions. In severe cases, the roots appear shortened, decayed, or brittle due to the destruction of root hairs.

Affected crops exhibit reduced tillering and delayed flowering. The overall vitality of the plant is noticeably reduced, leading to thinning of the stand.

Field diagnosis requires careful uprooting of the plant to inspect the roots, followed by laboratory diagnostic techniques such as nematode extraction and microscopic identification.

Integrated Pest Management (IPM) is essential for controlling this nematode. The primary strategy involves the use of resistant or tolerant crop varieties.

Crop rotation with non-host plants is highly recommended to disrupt the nematode's life cycle and starve the existing population in the field.

Good field sanitation practices, including the removal and destruction of infected root residues after harvest, are crucial for lowering the inoculum levels.

While chemical nematicides can provide short-term suppression, their use should be limited to high-pressure situations due to environmental and economic considerations.

• Maintain soil fertility to promote vigorous plant growth and root repair.
• Use biological control agents such as nematode-trapping fungi or antagonistic bacteria.
• Ensure adequate field preparation, including deep plowing, to reduce soil-borne nematode populations.