Damage. The damage caused by this species varies with the crop attacked. Onions show a loose puffy appearance (called bloat); carrots have a dry mealy rot; the stems of beans are swollen and distorted. Narcissus bulbs show brown rings when cut across and their leaves show raised yellow streaks.
Life cycle. This species attacks many plants, e.g. narcissus, onions, beans and strawberries. Several strains are known, but their host ranges are not fully defined. The 1 mm long nematodes enter plant material and breed continuously, often with thousands of individuals in one plant. When an infected plant matures, the nematodes dry out in large numbers, appearing as white fluffy eelworm wool that may survive for several years in the soil. Weeds, such as bindweed, chickweed and speedwells, act as alternate hosts to the pest.
Spread. This pest spreads mainly in infested planting material.
Control is achieved in several ways. Control of weeds (see chickweed); rotation with resistant crops, e.g. lettuce, brassicas (and cereals in commercial bulb growing areas); use of clean, nematode-free seed in onions; warm-water treatment (see Chapter 16) onions and narcissus at precisely controlled temperatures. All these methods help reduce this serious pest.
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