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Pest Description
IDENTITY: Scientific name: Heterodera medicaginis
Kirjanova, 1971
Common name: Alfalfa cyst nematode

NOTES ON TAXONOMY AND BIOLOGY: Like other cyst forming nematodes, it has sedentary endoparasitic habits. Cysts are persistent tanned sacs derived by the female body and contain the eggs. Cysts persist in soil for many years. Second-stage juveniles (J2) emerge from the cysts, penetrate host roots, and establish a specialized feeding site (syncytium) in the stele. They develop into swollen females, which retain the eggs and produce egg masses. Females rupture root cortex and protrude from root surface. At the end of the reproductive phase, females die and become lemon shaped dark to mid-brown cysts. These cysts are ambifenestrate and are provided of bullae and an underbridge.

GEOGRAPHIC DISTRIBUTION: This nematode is known to occur only in Russia.

HOSTS: Alfalfa is the only known host of this nematode. In greenhouse test the nematode failed to develop and reproduce on nine legumes (Gerber and Maas, 1982).

CROP LOSSES: Green matter losses of 46% were reported under arid conditions (Artokhina, 1984 cited by Cook and Yeates, 1993).

MEANS OF MOVEMENT AND DISPERSAL: This cyst nematode is dispersed with soil debris and plant material contaminated by the cysts.

RATING: (VL) Taking into consideration this nematode's limited distribution and host range, the risks posed by this cyst nematode to the US are rated very low.

    Cook, R. and G. W. Yeates. 1993. Nematode pests of grassland and forage crops. Pp. 305-350 in K. Evans, D. L. Trudgill, and J.M. Webster eds. Wallingford, UK: CAB International.
    Gerber, K., and P.W. Th. Maas.1982. A redescription of Heterodera medicaginis  Kirjanova. Nematologica 28:94-100.