Corn lesion nematode

Systematic position. Pratylenchus parazeae belongs to the phylum Nematoda, class Chromadorea, order Rhabditida, and the family Pratylenchidae. It is widely recognized as a major soil-borne endoparasitic pest that significantly impacts the productivity of maize and other cereal crops worldwide.

Host range. As the specific name implies, maize (corn) is the primary host for this species. However, it is a polyphagous pest capable of attacking a diverse array of crops, including wheat, sorghum, soybeans, and various grassy weeds. Its ability to survive on alternative hosts makes it a difficult challenge in many agricultural systems.

Biology and life cycle. This nematode is a migratory endoparasite, meaning it moves through root tissues during all motile stages. Eggs are laid in the soil or within the roots, where juveniles hatch and continue their development. The life cycle can be completed in as little as 30 to 45 days, depending on soil temperature and moisture levels, leading to rapid population buildup in the rhizosphere.

Nature of damage and pathogenicity. Pratylenchus parazeae causes distinct lesions on roots as it feeds on the cortical cells. These wounds reduce the root system's ability to uptake water and essential nutrients. Above-ground symptoms include uneven plant height, chlorosis, stunting, and premature wilting. Severe infestations often lead to root decay and significant grain yield losses in infected fields.

Control measures. Effective management requires an integrated approach to reduce population levels below the economic threshold:

• Implementing crop rotation with non-host crops to starve the nematode population.
• Maintaining soil fertility to help plants compensate for root damage.
• Controlling weeds that act as reservoir hosts during the off-season.
• Utilizing nematicides or biological control agents when high levels of infestation are detected.
• Ensuring proper soil drainage and moisture management to create unfavorable conditions for nematode survival.