Quality assurance in potato production

In recent years, quality problems in Swiss potato production have increased. In an on-farm experiment on 93 plots all relevant management, site and quality parameters are studied. The results can be summarised as follows: In 2001, only 30% of the plots fulfilled the Swiss quality standard without sorting out damaged tubers. For 19% the quality was even insufficient after sorting out damaged tubers. The proportion of plots with insufficient quality was highest for the organic farming system. In 2001, the most important external quality deficiencies were slug damage, wire worm and dry core. For all of them the position of potatoes in the crop rotation had an important influence. No serious attack of dry core was recorded after a fungicide treatment. An insecticide treatment in the preceding wheat crop could not always reduce wire worm damage sufficiently. A high occurrence of powdery scab was only observed for the variety Agria. No relationship could be found to soil pH. The starch content showed a high variability even within varieties, especially for Bintje and Agria. There was no clear influence of the farming system.