Low Incidence Of Fusarium In Organic Farming On Bread Wheat Grains Over A 13-Year Period

Organic farming has been questioned about its ability to manage Fusarium infestation compared with conventional farming. In this study, we monitored, over a 13-year period in several sites in France, the fungal incidence of four genera of fungi on bread wheat grains from organic farming. We collected samples immediately after harvest in conditions of natural contamination on a list of winter wheat varieties from 2006 to 2018 in several sites in France. From each sample, 100 kernels were surface disinfected, plated on potato dextrose agar, and colonies were identified at the genus level, and at the species level for Fusarium graminearum. The fungal incidence observed on kernels over the period was on average 88 ± 16% (i.e. mean ± standard-deviation). Kernels were mainly infected by fungal species of the genus Alternaria (71 ± 25%), while the incidence of Fusarium graminearum is usually very low in our context (1 ± 2%), with the exception of year 2008 (49 ± 12% and 17 ± 9%, respectively in the two sites studied), which is confirmed by the highly significant effect of the year and the ‘year × site’ interaction. To conclude, in our study, Fusarium graminearum appeared not to be a major concern for wheat production in organic farming systems.