Ditylenchus dipsaci




Rev 09/12/2023

Stem and Bulb Nematode Classification Hosts
Morphology and Anatomy Life Cycle
Return to Ditylenchus Menu Economic Importance Damage
Distribution Management
Return to Anguinidae Menu Feeding  References
    Go to Nemaplex Main Menu   Go to Dictionary of Terminology


           Ditylenchus dipsaci (Kuhn, 1857) Filipjev, 1936

Type species of the genus

Back to Top

Morphology and Anatomy:

Photomicrographs from Castillo et al., 2007
Nematode is 1.0-1.3 mm long.  

Stylet very short and delicate.

Glandular region of esophagus abutting intestine.

Female monovarial, prodelphic.

Races or biotypes are morphologically similar.


Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:


Back to Top


Cosmopolitan, especially in temperate regions where it is one of the most devastating plant parasites.  

In the western US, nematode populations can be dispersed by annual transport and migration of sheep from Colorado and Utah, although the nematode does not appear to pass through the gut alive.  Probably also associated with hay moved with sheep.

Sources of infestation

Spread to new areas


Spread within fields

Back to Top

Economic Importance:

C-rated pest in California Nematode Pest Rating System.

Dieback and wilting of foliage in ornamental Phlox from many parks in Japan causes causing significant commercial losses by reulting in reductions in the thousands opf visitors who visit the area in the Spring (Ikuyo et al., 2018).

Back to Top


Nematode is a migratory endoparasite.  

At the beginning of the crop season, 4th-stage juvenile enters young tissues, especially seedlings when below the soil surface. 

Feeding breaks down middle lamellae; nematode probably secretes a pectinase enzyme; plant parts become "crisp" and are easily broken.  

Migration on plant parts above ground requires free water, and may occur after rain or sprinkler irrigation in alfalfa. 

Nematode enters through stomata or by direct penetration.  

Foliar dieback in Phlox subulata in Japan (Ikuyo et al., 2018).    

Back to Top


Over 450 hosts for genus, but 8-10 host races or biotypes, some with limited host range.

Oat race: polyphagous on cereals, most grains, rye, corn, and oats.

Alfalfa race: rather specific on certain legumes, but alfalfa, many weeds, clovers.

Bulb race: most bulbs, daffodil, narcissus, and tulip.

Other hosts of D. dipsaci include onion, garlic, carrots, peas, potatoes, strawberry, sugarbeets; and various weed species.


For an extensive host range list for this species, click


Back to Top

Life Cycle:

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters


Monovarial, prodelphic, sexually reproducing.

Life cycle is 19-23 days at 15 C.  

Nematodes live 45-75 days when sexually mature; females each produce 200-500 eggs.  

Fourth stage juvenile (J4) is survival stage; it can enter a state of cryptobiosis (literally "hidden life") on or below surface of plant tissue - "eelworm wool" - 3-5 years survival (up to 23 years in museum specimens).    Survives in soil without host for as long as 2 years, probably feeding on fungi.

Back to Top


Plants become distorted and stunted; infected tissues are spongy; damage can predispose plants to other problems.


Infestation occurs readily in heavier soils and during times of high rainfall or in sprinkler-irrigated areas. 

Field shows irregular areas of sparse growth. 

Clover and alfalfa show reduction of internode length and swollen stems.

Nematode is spread around field by equipment, irrigation;  spreads readily in tail water.

Stand reductions up to 50% following high fall populations.

Predisposes alfalfa to Phytophthora megasperma.


Bean seed infected with Ditylenchus dipsaci


Ditylenchus dipsaci
damage to garlic cultivar Pata de Elefante  (left) compared to uninfested (right).
Samples from Tetela de Ocampo, Puebla State, Mexico.

Photograph by Ignacio Cid del Prado Vera

Onions, Garlic:

Bloated, twisted, swollen leaves, distorted and cracked bulbs. 

In garlic, infestation can become epidemic.

The nematode was introduced into Venezuela in Mexican varieties of garlic; up to 90% crop loss can occur. 

Cloves are infected through to the center where leaf primordia are located; therefore, treatment is difficult without affecting germination.

In 1999, growers in Kern County, California, bought garlic "seed" (cloves) from a nursery in Nevada.  The seed had not been heat treated because the nursery had not seen stem nematode in several years..  The growers sustained devastating crop losses and the nursery was sued for $25 million.  The nursery had liability insurance through a large company but that company sold the policies to several smaller companies.  As of November 1999, the smaller companies were demanding that every field from which losses were reported be sampled to demonstrate the presence of D. dipsaci.  That proved possible since there was garlic plant residue present in all the fields.

Oats and Rye:

Extra tillers, swollen leaf bases.

Photograph of symptoms on winter Barley by Chris Hogger (Switzerland).



Leaves distorted, yellowish swelling (Dutch call it "Spikkels"- see symptoms on garlic leaves), bulbs with dark rings.

In some plant species, inflorescence becomes infested, and pests are spread in the seed, e.g., beans, clover, and alfalfa; infestation can also be spread by infected bulbs.

Damage to plants

Signs and symptoms of damage

Components of crop loss


Photographs by Chris Hogger, Switzerland.  Effect of Ditylenchus dipsaci on growth (left), tap-root rot (above).

Ditylenchus dipsaci on sugarbeets in Germany (right), from Dr. Richard Sikora.

Extracts from correspondence with Dr. Sikora, University of Bonn, April 2003:

"We have a very serious problem in the Rhineland with the stem nematode on sugar beet.... the "Rubenkopfnematoden". ....... This is a unique problem that is now limited to Germany and Switzerland. We have lost all our nematicides and this is the main reason for it popping up so quickly.

Losses can reach a level in which the total field is plowed under. The nematode is reproducing in the beets after harvest and moving through the piles of beets at the factories. The farmers and sugar beet factories are in an uproar. No one has worked on it here in Europe for ages."

Damage by Sugarbeet Race of Ditylenchus dipsaci on sugarbeets in southern Spain. 
Photographs from Castillo et al., 2007.


Ditylenchus dipsaci has only been reported as a tobacco pest in Holland, France, Germany and Switzerland.  In those areas it causes a disease called "stem break".
The problem is not reported from other tobacco producing regions of the world.
Symptoms of stem break include small yellow galls on the stem. The galls increase in size and number and the galled tissue dies.  The stem becomes blackened and finally breaks.  Younger plants are more severely damaged than older plants (Lucas, 1986).
Ditylenchus dipsaci damage to celery in field (A) to tissues (B) and internally (C).  Photographs from Vovlas et al., 1993.
Back to Top


Hot-water treatment effective for dormant bulbs - narcissus - 44-45 C for 3 hours, but may be ineffective for many other crops.  

Hot water harmful to tulips, so cold water with addition of pesticide (e.g., thionazin) is recommended.  

Hot water can be used for onions and garlic;  formalin no longer used (banned), so Dr Westerdahl and others are refining procedures - see label.  

Also, water immersion of garlic cloves activates nematodes, which emerge; then follow with gutathion treatment - cost effective.

Systemic insecticides applied at very low rates (1 lb/acre) are also effective.  

Resistant alfalfa varieties include Washoe, Lahontan and Archer (Hafez, 1998). 

In Europe, resistant varieties of cereals are grown.  

Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click

Soil fumigation is usually not economical.  

Quarantines have been required in England and Holland to control spread of infestation.

Back to Top


Castillo, P., Vovlas, N., Azpilicueta, A., Landa, B. B., and Jimenez-Diaz, R. M. 2007. Host-parasite relationships in fall-sown sugar beets infected by the stem and bulb nematode, Ditylenchus dipsaci. Plant Dis. 91:71-79.

Hafez, S. 1998.  Fighting nematodes in alfalfa.  UC Davis Symposium.

Ikuyo, Y., Kabir, M.F., Ozawa, S., Koike, Y., Ishiguro, H. and Hasegawa, K. 2018. Characterisation and pathogenicity of Ditylenchus dipsaci isolated from Phlox subulata in Japan. Nematology 20:811-814.

Lucas, G.B. 1986. Plant-parasitic nematodes that attack tobacco. In Plant-Parasitic Nematodes of Bananas, Citrus, Coffee, Grapes and Tobacco. Union Carbide Agricultural Products Inc.

Vovlas, N., Melillo, V.A., Catalano, I. 1993. Ditylenchus dipsaci, causal agent of severe damage in celery crops in Apulia (Southern Italy).  Nematologia Mediterranea 21:55-57.

Back to Top

Copyright © 1999 by Howard Ferris.
Revised: September 12, 2023.