Corn root lesion nematode

Taxonomic classification: Pratylenchus zeae is classified under the phylum Nematoda, class Chromadorea, order Rhabditida, and family Pratylenchidae. It is a migratory endoparasitic nematode, widely recognized as a major soil-borne pathogen in tropical and subtropical agricultural systems.

Diseases and host plants: The nematode causes root lesion disease, characterized by necrotic brown spots on the roots of various crops. Primary hosts include maize (corn), rice, sugarcane, sorghum, wheat, and tobacco. Infestation results in reduced root surface area, which leads to diminished water and nutrient uptake, causing overall crop stunting.

Biology and life cycle: The life cycle of Pratylenchus zeae consists of an egg stage, four juvenile stages, and the adult stage. The entire life cycle takes approximately 30 to 45 days. Both juveniles and adults act as migratory parasites, moving through the root cortex, destroying cells, and creating tunnels that allow secondary infection by fungi and bacteria.

Conditions for development: This nematode thrives in warm, moist, and well-aerated soils, showing peak activity at temperatures between 25 and 30 degrees Celsius. It is highly prevalent in sandy soils with low organic matter. Dissemination typically occurs through movement of soil contaminated with cysts or active stages, infested root debris, and irrigation water.

Economic impact and management: Damage caused by Pratylenchus zeae often leads to significant yield losses, especially under drought conditions where the damaged root system cannot support the plant's needs. Integrated pest management (IPM) is essential for control:

• Crop rotation with non-host or antagonistic cover crops.
• Strict sanitation protocols for farm machinery and equipment.
• Use of certified pathogen-free seeds and seedlings.
• Application of chemical nematicides where infestation levels exceed economic thresholds.
• Promoting soil health through organic amendments to enhance biological control.