Soil Fusarium Antagonism and Resource Competition as Potential Mechanisms for Suppression of Bayoud Disease in Moroccan Date Palm Cultivation

Bayoud disease, caused by Fusarium oxysporum f. sp. albedinis ( Foa ), poses a significant threat to date palm cultivation in North Africa. However, there is a lack of in-depth studies on the soil microbial ecology governing disease development. This study explored the outcomes of nutrient competition among soil-borne Fusarium species and their antagonistic effects on Foa. We assessed the nutritional profiles of Fusarium isolates from three different soils: a suppressive soil from Marrakech ( Fus_M ) and two conducive soils from Errachidia ( Fus_R ) and Zagora ( Fus_Z ), using Biolog SF-P2 plates. Co-inoculation tests were performed to evaluate the inhibitory activity of each Fusarium isolate on Foa . Chemical analyses of soils show that suppressive soils are rich in nutrients, while conducive soils are poor in nutrients. Fus_M exhibited the greatest growth compared to Fus_R , which showed growth similar to that of Foa . Furthermore, Fus_Z significantly inhibited Foa growth by 23% versus 17% and 15% for Fus_M and Fus_R . Additionally, Fusarium isolates from Zagora ( Fus_Z ) shared 94% of the utilized nutrients, which was significantly higher than that of Fus_R (88%) and Fus_M (84%). These results suggest that disease suppression in the suppressive soil ( Fus_M ) was the effect of both nutrient competition and antagonistic interactions between soil Fusarium and the pathogen. Overall, this study highlights the importance of integrating an ecological approach to develop effective management strategies against Fusarium wilt in date palms.