Gold nematode
| Gold nematode | ||||||||||||
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Typical cyst shape |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Globodera rostochiensis | ||||||||||||
| ( Wollenweber , 1923) |
The gold nematode or yellow potato cyst nematode ( Globodera rostochiensis , syn .: Heterodera rostochiensis ) is a roundworm (nematode) that parasitizes on the roots of the potato . The cyst-forming nematode is a major pest on potatoes. It was first discovered in 1913 near Rostock and therefore got its name rostochiensis .
Symptoms and Biology
The characteristic feature of the infestation of the potato plant by gold nematodes are the cysts that can be observed on the roots. They correspond to a transformation of the females after fertilization. These cysts are brown, resistant, spherical "pockets" filled with eggs. A single cyst is between 0.1 and 0.8 mm in diameter and can contain between 200 and 1000 eggs. The contents of the cyst can survive in the soil for 8 to 10 years. Because the cysts are only formed by the females, there is a sexual dimorphism in the adults : the males and the larvae are small (less than 1 mm), mobile and thread-like. During the growing season, the larvae hatch from the cysts and invade the roots. Hatching is favored by moisture and root excretions. The abdomen of the females swells up, the periodontal membrane breaks open and the cyst-shaped nematodes, only anchored in the tissue with the mouth part, come to lie on the outside. The total cycle between rupture and maturation of the cyst is approximately 60 days. Usually one generation develops each year. In exceptional cases, up to three generations per year can be observed.
The development of the gold nematodes is influenced by various factors. More cysts are found in light soils (sandy or peat soils) than in heavy soils (loam or clay soils). Active larvae appear from 12 ° C. For a successful development, however, temperatures of over 15 ° C are required. Accordingly, the number of nematodes in potato cultivation is low before June. A strong development follows in July and August, which can continue into October. Thereafter, no more larvae are formed. According to this cycle, gold nematodes are not a problem on new potatoes.
The damage caused by the gold nematodes depends on the soil, climate and the number of nematodes. Potato growth is inhibited by secretions from the nematodes. The leaves turn yellow and the roots are heavily branched with yellowish-white cysts. Since the gold nematodes are not very mobile, they are principally spread passively. Water and wind are important for this spread. But the main factor is people. The greatest danger lies in the use of infected potato tubers as plant material. In this way, the cysts can be spread even if large crop rotation intervals are observed. Soil on machines, tools and shoes can also act as a diffusion factor.
Combat
The most important preventive control measure is a break in cultivation of 4 to 5 years between two potato plantings. If there is massive damage in a planting season, even an 8 to 10 year break is required. Other preventive measures, e.g. B. the choice of resistant varieties are also important, as the options for chemical control are severely limited.
literature
- Horst Börner: Plant diseases and plant protection , 7th edition, UTB 518, Verlag Eugen Ulmer Stuttgart
- La défense des plantes cultivées, R. Bovey, Payot, Lausanne, 6ème édition, 1972
Web links
- Globodera rostoochiensis at nematode.net