Contribution of airborne inoculum monitoring in the improvement of late blight management

Le Vourch, Vivien [UCL] Decroës, Alain [UCL] César, Vincent [UCL] Legrève, Anne [UCL]

Quantification of airborne inoculum has been used for decades to understand the epidemiology of plant diseases and could be used to improve disease management. The daily spatio-temporal distribution of airborne inoculum of Phytophthora infestans has been investigated in Belgium using a network of Burkard spore traps combined with quantitative PCR assay since 2018. Great variations in daily quantities of airborne inoculum were observed between sites and between years. In the 14 monitored fields, the presence of inoculum in the air preceded the apparition of late blight disease in the untreated plots set up around the spore traps. Comparison between airborne inoculum detection and recommendation provided by late blight decision support systems revealed that fungicides treatments are recommended in many cases in the absence of airborne inoculum. Monitoring or prediction of this inoculum could enable to reduce the number of treatments, especially by delaying the first treatments. Further knowledge in relationships between disease pressure in fields, airborne inoculum and meteorological conditions will provide valuable information for improving decision support systems and reducing fungicide use.