Survey on the health of potato seeds and potato crops in Northwest Syria reveals first findings of non-indigenous potato pathogens, Geotrichum candidum (causal organism of Rubbery Rot) and Macrophomina phaseolina (causal organism of Charcoal Rot)

Abstract Potato is an important food crop in Syria, particularly during the current crisis. Healthy seed stocks are vital in maintaining yields and quality, but the crop health risks associated with imported and home-multiplied seed are unknown. Between 2020–2022 pathogens in locally multiplied seed (LMS), and imported seed potatoes (ISP) and open fields grown from these sources were surveyed. Seed tubers from LMS and ISP were assessed using mass spectrometry (MOLDI-TOF MS). There was a greater prevalence of pathogens in LMS, although some important potato pathogens were also detected on ISP. On LMS seven fungal pathogens were detected, including Geotrichum candidum (causal organism of rubbery rot) on 35% of the samples and Macrophomina phaseolina (causal organism of charcoal rot disease) on 17% of the samples. These are first reports of these pathogens in Syria. On ISP four fungal pathogens were detected in 2022. The incidence of the detections was lower on IPS, although disease severity was similar to those found on LMS. Quarantine pathogens were not detected in either source. Field diseases assessments in northwest Syria showed a high prevalence of disease symptoms in crops grown from LMS. In crops grown from ISP disease levels were much lower, however results may be confounded by the fact that crops grown from ISP were surveyed in a spring growing season, and the crops raised from LMS were surveyed in autumn growing seasons. Nevertheless, the research highlights the lower health status of LMS.