Garlic Stem and Bulb Nematode

📖 Description

Ditylenchus dipsaci, the Stem and Bulb Nematode, is one of the most economically devastating plant-parasitic nematodes of temperate and subtropical Allium production worldwide. It is an endoparasitic migratory nematode — unlike root-knot nematodes that establish a permanent feeding site, D. dipsaci moves actively through host tissue, feeding on parenchyma cells and inducing cell-wall modifications that produce the characteristic swollen, distorted growth. The nematode exists as a complex of more than 20 biological races, each with a different host range — the ‘allium race’ is the most damaging to garlic and onion and is widely distributed across India’s Allium belts. The pest’s most remarkable adaptation is its ability to enter cryptobiosis — the J4 stage can survive in a dehydrated state for years inside dry plant tissue, soil, or on farm equipment, reviving instantly when moisture returns. This makes eradication extremely difficult once a field is infested. The garlic belt of Madhya Pradesh (Mandsaur, Neemuch, Ratlam), which produces over 40 % of India’s garlic, has emerged as a hotspot for D. dipsaci infestation since 2015, driven by the widespread use of farmer-saved seed cloves of unknown health status. The National Horticulture Mission now supports a clean-seed programme based on hot-water treatment and tissue-culture propagation. Climate change projections suggest the pest may expand its range northward into Uttar Pradesh and Punjab’s Allium belts, which were historically too hot and dry for the nematode’s lifecycle.