Heterodera schachtii

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Heterodera schachtii - damage on sugar beet (right, left healthy plant) (click on image to enlarge it)
Author(s): Gerald Holmes, Valent USA Corporation
Source: IPM Images

Heterodera schachtii Schmidt, 1871 - (sugarbeet cyst nematode)

The nematode is found mainly in temperate regions as a parasite of sugar beet. Various other crops from the families Amaranthaceae and Brassicaceae as well as from other families can be also attacked. Infected plants are stunted and wilt with the outer leaves turning yellow. In sugar beet, the main root develops poorly and the sugar content is reduced. Seedlings may be killed. Infestations often develop as patches in a field. Yield reductions can reach 50% and the yearly economic damage in Europe alone has been estimated at € 80 million (1999).

Cysts and eggs can persist in the soil for up to 10 years. In response to chemical stimuli from the roots of a host plant, the second stage juvenile hatches from the egg, migrates through the soil and penetrates a fine root tip. Inside the root, it excretes substances which cause the attacked root cell to merge with neighbouring cells. This merger process results in a large multinucleate structure in the root (a syncytium) which serves as feeding site for the developing nematode.

Vernacular names
• Deutsch: Rübenzystennematode
• English: sugarbeet cyst nematode
beet cyst nematode
• Español: nematodo de la remolacha
• Français: nématode à kyste de la betterave
nématode de la betterave

The development goes through a 3rd and 4th juvenile stage. Males reach a length of about 1-1½ mm and then leave the roots to search for females. Females remain in the root, swell with part of their body extruding from the root. They become fertilized and filled with several hundred eggs. Eventually, the whole female becomes a durable, lemon-shaped cyst, almost 1 mm long and completely filled with eggs. The development from the penetration of the root to the formation of eggs lasts 1-2 months and there are 3-4 generations per year.

The cysts can spread to other fields through soil attached to farming equipment, vehicle tires or animal hooves. Infested fields should be planted with a non-host crop for several years. Equipment and harvested beets should be cleaned from soil. Early planting, resistant cultivars and nematicides are also used as management tools.