Title : The susceptibility of gramineous and non-gramineous weeds to fusarium culmorum infection
Abstract:
Weeds can play an important role in facilitating the infection of wheat fields with the fungal phytopathogen Fusarium by acting as an alternative host. It has already been shown that infected perennial weeds on the edges of agricultural fields can significantly increase the presence of Fusarium in nearby wheat ears by acting as overwintering vessels for the phytopathogenic fungi. Some empirical studies have also reported that gramineous weeds host more overwintering Fusarium than non-gramineous weeds, but it is unclear whether or not these observations are due to innate susceptibility differences in the weeds. The main objective of this study was to identify differences in the reaction of different weed species to infection by Fusarium culmorum. In order to do this, we grew gramineous and non-gramineous weeds in a climate chamber and infected them with a pathogenic Fusarium culmorum strain through the roots. The plants were analysed after 3 and 9 weeks after infection in order to observe the development of the infection in the rhizo-, endo- and phyllosphere of the weeds over time. We determined that while gramineous weeds were more infected in the roots than non-gramineous weeds, they were less infected in the shoots. This implies that our hypothesis that gramineous weeds are just generally more susceptible to Fusarium infection cannot be confirmed in this experiment. We also found that the roots were already infected after three weeks and that there was a large increase in the infection load of all weeds between three and nine weeks post initial infection. Despite high infection loads in infected plants, there were no clear visual differences between them and the control plants. The large differences in the mean fungal load detected in the different weed species was also very high. Further research should focus on whether the trends mentioned above are observed when different Fusarium species or strains and other infection methods are used to assess the susceptibility of the different weed species. Alternatively, further research could also focus on exploring how the large differences in the susceptibility of common weed species to fungal pathogens such as Fusarium culmorum could be used for practical ecological applications and phytopathogen infection mitigation.
