Stem and bulb nematode

The stem and bulb nematode (genus Anguilla, family Anguinidae, order Tylenchida) is a highly destructive microscopic plant-parasitic worm. Unlike root-knot nematodes, this species specifically targets the stems, bulbs, and leaves of plants, migrating through internal tissues and causing systemic physiological dysfunction that leads to stunted growth and widespread crop loss.

This pest has an exceptionally broad host range, affecting over 400 species of plants, including essential agricultural staples such as onions, garlic, potatoes, strawberries, and various legume crops. Its ability to survive in seeds, soil, and agricultural machinery makes it a major concern for both commercial farmers and home gardeners, as it can be easily transported across different fields.

The biological cycle of the nematode is adapted to the host plant's development. Larvae and adults penetrate the plant tissue, where they multiply rapidly under conditions of high humidity. The lifecycle consists of several stages, and their maturation depends heavily on temperature. Notably, the nematode can survive in a state of suspended animation (anhydrobiosis) for years, making it notoriously difficult to eradicate from infested soils.

Damage caused by this pest is distinctive. Infested plants often exhibit symptoms such as swollen, twisted, or distorted stems and leaves. Bulbs become soft, discolored, and prone to secondary bacterial or fungal rot. In severe cases, the entire plant structure collapses, or the bulb decomposes completely in storage, causing significant post-harvest losses if the infection is not identified early.

Effective management requires an integrated pest management approach. Key strategies include the use of nematode-free planting stock, as infested bulbs are the primary transmission vector. Implementing long crop rotations using non-host crops is vital to starve the nematode population in the soil. Additionally, deep plowing and the removal of weed hosts help break the pest's cycle, ensuring better field sanitation for future planting seasons.