Aspects of resistance of flax and linseed (Linum usitatissimum) to Fusarium oxysporum f.sp. lini = Aspecten van de resistentie in vezel- en olievlas (Linum usitatissimum) tegen Fusarium oxysporum f.sp. lini

In the thesis aspects have been described of the flax and linseed interaction to Fusarium oxysporum f.sp. lini, the causal agent of flax wilt. Two in vitro tests were established to screen for resistance, to investigate race specificity and to study infection and colonization patterns in a resistant and a susceptible cultivar. The fungus appeared to colonize the cortex, causing root rot initially, followed by colonization of the protoxylem vessels. Several aspects of quantitative screening for resistance were investigated by visual disease screening, physiologic parameters, and ergosterol measurements. The results indicated that symptoms are related to resistance rather than tolerance. Race specificity was studied in vitro, and in an international field experiment performed at six locations in Europe and three in North America. Although significant genotype * isolate interaction and significant genotype * environment interaction was observed, possible races of the fungus could not be identified. No indication was obtained for race-specific resistance in flax and linseed.