Atta Ur Rahman1, Maria Munawar1, Michael Harding2, Michele Konschuch1, Mario Tenuta3, Dmytro P. Yevtushenko1
1Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, T1K 3M4
2Alberta Agriculture and Forestry, Crop Diversification Centre South, Brooks, AB T1R 1E6 3Department of Soil Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
Potato early dying (PED) disease complex is characterized by plant stunting, wilting, premature senescence, reduced tuber yields, and is associated with complexes of soilborne fungi Verticillium dahliae, V. albo-atrum, Colletotrichum coccodes, nematode Pratylenchus penentrans, and possibly other pathogens. The severity of PED depends on the species involved, inoculum density, and the virulence of the resident strains. Hence, this study aims to isolate and identify the resident species involved in PED and to determine the inoculum density of V. dahlia and P. penetrans in southern Alberta’s potato growing region. Soil samples were collected from 30 fields in the fall of 2020. Verticillium spp. and root lesion nematodes were quantified in the soil using the traditional plate-counting method and qPCR. Before planting, soil samples were collected again in the spring of 2021 to quantify the pathogen levels at the beginning of the cropping season. Plants were assessed for disease severity, and tissue samples were collected throughout the growing season to molecularly detect and isolate pathogens colonizing plant tissues and possibly contributing to PED. About 120 pure cultures of fungi have been isolated from potato stems, including the genera Chaetomium, Verticillium, Colletotrichum, Alternaria, and Fusarium. C. coccodes was detected in 98% of the samples collected during tuber bulking and maturation stage, whereas V. dahliae was detected in 82% of the samples. At harvest, plants were assessed for tuber yield to determine region-specific thresholds for disease development. The result obtained in this study will help elaborate on how PED progresses during the growing season and what biological factors contribute to yield reductions.