Peter-Frans de Jong

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OF CARBON STEEL PLATES USING PULSED EDDY CURRENTS V.O. de Haan and P. de Jong 1 BonPhysics Research and Investigations BV, Putterhoek, The Netherlands; 2 Röntgen Technische Dienst bv, Rotterdam, The Netherlands Abstract: It is well know from literature that Pulsed Eddy Currents generated by switching off a stationary current through a coil above a carbon(More)
The growth of leek rust epidemics in time under favourable conditions in three leek cultivars during two years was analysed. In both years, the highest disease levels were found on cultivar Albana, followed by Carina and Cortina. A simple model is presented to correct the results for exchange of inoculum between adjacent plots. The results of this model(More)
A model is presented which simulates chemical control against leek rust under a system of supervised control. The spread of disease between fields in one farm and the influx of spores from outside is part of the model. The possible reduction in fungicide sprays against leek rust following various preventive measures is estimated with this model. Results(More)
The shape of the mesopores in a series of Y zeolites modified with different postsynthesis treatments was investigated. A combination of 3D-TEM (3D-TEM ) three-dimensional transmission electron microscopy) with texture analysis (nitrogen physisorption and mercury porosimetry) enabled us to discriminate between cylindrical mesopores and mesoporous cavities(More)
Leek rust, caused byPuccinia allii Rudolphi, is an important disease of leek (Allium porrum L.) in the Netherlands. For the development of a practical sampling method for early detection of leek rust in commercial fields, information on the spatial distribution of the disease is necessary. In this study, the spatial distribution of diseased plants during(More)
Based on a simple model, the possible effects of certification of planting material on the occurrence of leek rust in a region can be derived from information on the proportion of infected fields (v) and the proportion of newly planted fields with infected planting material (i) in that region. Ifv ≤ √i, certification of planting material will be highly(More)
To establish control thresholds for chemical control of powdery mildew (Erysiphe cruciferarum) on Brussels sprouts, mildew intensity on leaves and buds was observed on the cultivars Lunet, Tardis and Asgard during three years in unsprayed plots. Mildew infection on the leaves was observed from late August onwards, increasing to moderate or high levels. In(More)
Brown spot disease on pear caused by Stemphylium vesicarium may affect leaves and fruits. Inoculum sources present on orchard floors play an important role in the epidemiology of pear brown spot. The pathogen can overwinter on plant residues and multiply and spread on the residues during the growing season. In the Netherlands, brown spot characteristically(More)
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