**Morphology and Biology**:
– Ditylenchus dipsaci is a microscopic worm about 1.5mm long.
– They penetrate plants from soil, infested planting material, and seeds.
– Females lay 250 eggs per season, with 6 generations developing in optimal conditions.
– Symptoms include curling onion leaves, yellowing garlic leaves, loosened bulb scales, and cracked bulb necks.
– Other hosts include peas, beetroot, pumpkin, rhubarb, and ornamental bulbs.
**Lifecycle**:
– The lifecycle occurs in 5 stages with molts happening in egg and soil.
– Juveniles enter plants through young tissue or seedlings.
– Reproductive cycle lasts 19-25 days; a female can lay 200-500 eggs.
– Nematodes can halt the lifecycle in unfavorable conditions.
– Lifespan is about 70 days, overwintering in dried infected host material.
**Distribution and Environment**:
– Ditylenchus dipsaci is found in most temperate areas globally.
– Can kill 60-80% of crops in infested areas.
– Environment: 15-20°C temperature range and moisture for movement.
– Not usually found in tropical regions.
– Races are diverse in Europe, Mediterranean, Americas, Africa, Asia, and Oceania.
**Disease Cycle**:
– Spread through irrigation water, tools, and animals.
– Enters plants through stomata or wounds.
– Feeds on parenchymatous cells and releases pectinase.
– Causes gall formation and allows entry of secondary pathogens.
– Symptoms include stunted growth, leaf curl, swollen stems, and bulb malformations.
**Hosts and Symptoms**:
– Major damage in garlic, onion, carrot, fava bean, alfalfa, oats, and strawberry.
– Infects 400-500 plant species worldwide.
– Specific symptoms in Allium species, garlic, and fava beans.
– Management strategies include prevention, hot-water treatments, sanitation, crop rotation, and avoiding planting susceptible crops during peak nematode infection seasons.