Isolation and Identification of Cucumber Root Rot-Associated Fungi and Assessment of Their Pathogenicity

Abstract

Abstract This study was conducted at the Laboratories of the Crop Protection Directorate / Ministry of Agriculture – Iraq for isolating the causative agents of cucumber root rot disease from various sites in Baghdad, Salah al-Din, Sulaymaniyah, and Basra provinces in Iraq, and testing their pathogenicity on cucumber seeds in the laboratory Results of isolation and diagnosis revealed the presence of several plant-associated fungi that varied in appearance across different regions The fungus Rhizoctonia solani was the most prevalent, as it appeared in the majority of the isolated samples, totaling fifteen isolates, while the isolates of Fusarium spp and Macrophomina phaseolina reached 5 and 2 isolates, respectively The results of pathogenicity assessment for 22 fungal isolates indicated that all tested fungi significantly reduced the germination rate of cucumber seeds Germination rates in their treatments ranged from 0-43.3% compared to 100% in the control Isolates R7 to R15 of R. solani, 1F to F5 of Fusarium. spp, and isolates M1 and M2 of M. phaseolina exhibited significant superiority over other isolates, which completely inhibiting seeds germination, while the germination rates for isolate treatments R1, R2, R3, R4, R5, R6 reached 43.3, 36.6, 20, 10, 30, 6.6%, respectively