Beet cyst nematode in vegetables

Page last updated: Wednesday, 19 October 2016 - 7:26am

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Life cycle

Cyst nematodes are extremely problematic because they can persist for years in soil without a host. Their remarkable persistence is due to their ability to produce a cyst, which is the hardened dead body of the female nematode that surrounds and protects the eggs from adverse environmental conditions.

Each cyst contains several hundred dormant eggs which hatch slowly over years when stimulated by moisture and root exudates from growing host plants (Figure 3).

Microscopic photograph of nematode cysts showing several hundred eggs (Ulrich Zunke, University of Hamburg, Mactode Publications)
Figure 3 Nematode cysts contain several hundred eggs (Ulrich Zunke, University of Hamburg, Mactode Publications)

Juveniles are attracted to the roots, infecting near the tips, causing roots to branch profusely. They feed within the roots and develop into adults.

When mature, males emerge from the roots while females remain sedentary. Females become lemon-shaped, protrude from the root surface and can be seen as small white-yellow dots about the size of a pin head. The female dies and her body, which contains many eggs, hardens to form a cyst. The cyst detaches from the roots to remain in the soil.

Development from root penetration to the mature cyst takes about four to eight weeks, depending on temperature. Optimum temperature for growth and reproduction is 21 to 27°C. Several cycles may occur during the growth of the host plant and greater damage may occur in summer when soils are warmer and plants tend be under increased environmental stress.

As many as five generations per season are possible in warmer climates, when plants are re-invaded by freshly hatched juveniles within one growing season.

Beet cyst nematode in vegetables


Sarah Collins