Stem and bulb nematode

Stem and bulb nematode

Ditylenchus dipsaci

Common name:

Stem and bulb nematode

Scientific name:

Ditylenchus dipsaci

Alternative common names:


Stem and bulb nematode is a roundwormthat lives in soil and plant tissues, primarily infectingonionandgarlic plants. The feeding and movement of the nematode causes large cavities in the infected tissue. Infestation is encouraged by wet conditions and mild temperatures (15-20 °C), and is adversely affected by dry conditions and temperatures below 10 °C and above 22 °C.

Additional Information

Where does this species come from?

Europe, the Mediterranean region, North and South America, northern and southern Africa and Asia.

What is its invasive status in South Africa?

NEMBA Category 1b

Where in South Africa is it a problem?

Mpumalanga, Free State, North West, Northern Cape and Limpopo.

How does it spread?

Spreads through irrigation water, contaminated farming equipment and animals.

Why is it a problem?

It causes complete failure of host crops. Infected soils cannot be used for onion cultivation for decades.

What does it look like?

Description: Stem and bulb nematodes are very small roundworms, approximately 1.5mm long. They look like tiny cellophane noodles, slithering in and out of the bulb, roots and neck of the garlic or onion plant. They are capable of living without water and can tolerate desiccation for several years.

Habitat: They live between the cells of onion or garlic leaves and between the scales of the bulbs, where they feed on cell sap and multiply. They prefer moist soil.

Breeding: Except in cold weather, reproduction occurs throughout the year, with a typical life cycle taking between 19 and 23 days at 15°C. When sexually mature, the nematode lives for between 45 and 75 days, each female being capable of producing up to 500 eggs.

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