Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2010
Publication Date: 6/23/2010
Citation: Olanya, O.M., Porter, G.A., Lambert, D.H., Starr, G.C., Larkin, R.P., Bradbury, B. 2010. Effects of supplemental irrigation and soil management on potato tuber diseases. Plant Pathology. 9:68-72. Interpretive Summary: Application of supplemental irrigation can improve potato yield in years of inadequate rainfall, but may also have deleterious effects by providing moisture which can increase the incidence of some potato diseases. We compared irrigation, soil amendment, and crop rotation for their effects on tuber diseases. The incidence of tuber diseases such as black scurf, black dot, silver scurf and common scab varied among irrigation treatments, amendments, and rotations. Disease levels varied among cultivars, and were greater on Superior and Shepody than on Atlantic and Russet Burbank. This study shows that careful application of supplemental irrigation is required to reduce the likelihood of disease development on potato.
Technical Abstract: Supplemental irrigation and soil management can improve potato growth and tuber yield in deficit rainfall, but may also impact potato tuber diseases. The comparative effects of irrigation, soil amendment and crop rotation on tuber disease incidence were quantified in long-term potato cropping systems plots. Surface sprinkler irrigation water was applied intermittently in late July or early August of each year, based on tensiometer or moisture block readings. Black scurf (Rhizoctonia solani), black dot (Colletotricchum coccodes), silver scurf (Helminthosporium solani) and common scab (Streptomyces scabei) diseases were quantified on potato tubers randomly sampled at harvest and kept at optimum storage temperature (7.2 C) prior to visual disease assessments. The incidence of tuber diseases varied among irrigations and significant treatment effects (P<0.05) were observed for black dot, black scurf, silver scurf and common scab diseases. The mean incidence of black scurf ranged from 0.68-4.54%, and 9.39-23.25% in 1996 and 1997, respectively. The average incidence of black dot was 0.70-6.78% in 1996, and 40.4-44% in 1997. The effects of soil amendment, rotation, and their interactions on tuber diseases varied across years. Disease incidence differed significantly (P<0.05) among cultivars and was greater on Superior and Shepody than on Atlantic and Russet Burbank. This study shows that irrigation has variable effects on tuber disease incidence, and cultivar susceptibility can significantly impact selective potato tuber diseases.