Yield and disease tolerance of potato cultivars grown under conventional and organic cultural management practices

A field experiment was carried out during spring-summer 2003 at the experimental farm of CCORAV located at Grotte di Castro, Viterbo, Central Italy to evaluate five potato cultivars under conventional and transitional organic management for tuber yield and tolerance against pests and diseases. Experimental design was a split-plot with three replicates; treatments were a factorial combination of 2 cultural management practices (main plot) x 5 cultivars ('Elodie', 'Aladin', 'Arielle', 'Konsul', 'Almera'). Organic cultural practices adopted were established according to the requirements of the European Union Organic legislation (2091/92 and amendments), while conventional practices were those usually adopted by the potato growers of Lazio region. Results showed that 'Aladin' and 'Almera' are suitable varieties for growers of Lazio region which are interested to switch from conventional to organic management system due to the highest marketable yield especially of medium size tubers (diameter 45-75 mm) and the low incidence of disease problems (common scab). Concerning wireworm attacks, the percentage of pest incidence was almost 9 times higher in organic system in comparison to conventional system leading to a reduction of marketable yield of medium tuber size.