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Potato cyst nematode
Potato root nematodes or potato cyst nematodes (PCN) are 1-mm long roundworms belonging to the genus ''Globodera'', which comprises around 12 species. They live on the roots of plants of the Solanaceae family, such as potatoes and tomatoes. PCN cause growth retardation and, at very high population densities, damage to the roots and early senescence of plants. The nematode is not indigenous to Europe but originates from the Andes. Fields are free from PCN until an introduction occurs, after which the typical patches, or hotspots, occur on the farmland. These patches can become full field infestations when unchecked. Yield reductions can average up to 60% at high population densities.
==Biology==
The eggs hatch in the presence of Solanoeclepine A, a substance secreted by the roots of host plants. The larvae then invade the tips of the root and establish a feeding site. Both susceptible and resistant potato varieties will suffer from growth retardation at low and medium populations densities. At very high population densities mechanical damage of the root system will occur (Seinhorst, 1986). The female individuals swell up and appear as cysts on the surface of the roots, each containing up to 400 eggs. In temperate zones only one generation per year will occur. In the Mediterranean countries sometimes a second generation is reported. Cysts can then also be found on the skin of the tubers. Each year without host a certain fraction of the eggs will hatch (spontaneous hatch). The eggs can survive for up to 20 years inside these cysts.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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