Potato cyst nematodes (PCN) are in the Northern Netherlands and the Weser-Ems Region in Germany a major issue for farmers. The yearly average damage by PCN is about 100 Euros/hectare for farmers. Infestations of potato cyst nematodes can be controlled in a sustainable way by proper potato variety selection. Potato varieties vary in the degree of tolerance and resistance to PCN. However, this knowledge is used by only a small fraction of the farmers. The AGROBIOKON project, which is funded by the INTERREG EDR-region, the Landwirtschaftskammer Niedersachsen and the Dutch farmers association, have developed a decision support system for potato variety selection based upon population dynamic models for PCN: OPTIRas. The scientific principles and the model behind the decision support system will be presented. The model will be applied to PCN field experiments in the Weser-Ems region. Experience of using this decision support system in farmer study groups in the Netherlands and Germany will be shared.
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Field experiments were carried out in 1991 and 1992 on sandy soil highly infested with the potato cyst nematode Globodera pallida. Half the trial area was fumigated with nematicide to establish two levels of nematode density. Three levels of soil compaction were made by different combinations of artificial compaction and rotary cultivation. Two potato cultivars were used in 1991 and four in 1992. Both high nematode density and soil compaction caused severe yield losses, of all cultivars except cv. Elles which was tolerant of nematode attack. The effects of the two stress factors were generally additive. Analysis of the yield loss showed that nematodes mainly reduced cumulative interception of light while compaction mainly reduced the efficiency with which intercepted light was used to produce biomass. This indicates that nematodes and compaction affect growth via different damage mechanisms. Nematodes reduced light interception by accelerating leaf senescence, by decreasing the specific leaf area and indirectly by reducing overall crop growth rate. Partitioning of biomass between leaves, stems and tubers was not affected by nematode infestation but compaction decreased partitioning to leaves early in the growing season while increasing it during later growth stages. The effects of nematodes and compaction on root length dynamics and nutrient uptake were also additive. This suggests that the commonly observed variation in yield loss caused by nematodes on different soil types is not related to differences in root system expansion between soils of various strength. Cv. Elles, which showed tolerance of nematodes by relatively low yield losses in both experiments, was characterised by high root length density and thick roots. These characteristics did not confer tolerance of soil compaction, since compaction affected root lengths and tuber yields equally in all cultivars. In the first experiment only, high nematode density led to decreased root lengths and lower plant nutrient concentrations. The yield loss which occurred in the second experiment was attributed to the effects of nematodes on other aspects of plant physiology. Copyright © 1995, Wiley Blackwell. All rights reserved
DOCUMENT
Growth curve analysis of sedentary plant parasitic nematodes on different hosts and at different population densities is used to assess plant suitability including their resistance and tolerance. The estimated parameters of host suitability can be used in pest management programs for economic important species such as potato cyst nematodes.
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