Submitted to: Australian Journal of Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2009
Publication Date: 2/18/2010
Citation: Olanya, O.M., Porter, G.A., Lambert, D.H. 2010. Supplemental irrigation and cultivar effects on potato tuber diseases. Australian Journal of Crop Science. 4:29-36. Interpretive Summary: Application of supplemental irrigation can improve potato yield in years of reduced rainfall, but may also have undesired effects on tuber diseases. The effects of irrigation and plant variety on potato tuber diseases were assessed in this study. The incidence of black scurf, black dot and silver scurf diseases varied among irrigation treatments and ranged from 1 to 44%. Disease levels varied among plant varieties, and were greater on Superior and Shepody than on Atlantic and Russet Burbank. This study showed that careful application of supplemental irrigation is required to reduce the likelihood of disease development on potato. Selective use of potato varieties along with optimal water management provide opportunities for reducing tuber diseases in potato.
Technical Abstract: Supplemental irrigation can improve potato growth and tuber yield under deficit rainfall conditions, but may also impact potato tuber diseases. The comparative effects of irrigation on tuber disease incidence were quantified on four cultivars, in long-term potato cropping systems experiments. Surface sprinkler irrigation was applied in July and August of each year, based on tensiometer or moisture block readings, with the goal of maintaining soil water to the required treatment levels. 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 stored at 7.2 C. The incidence of tuber diseases varied among irrigations and significant treatment effects (P<0.05) were observed for black dot, black scurf and silver scurf diseases in some years. The mean incidence of black scurf ranged from 0.7-5% in 1996 and 9-23% in 1997. The average incidence of black dot ranged from 14-25% and 26-44% in 1996 and 1997, respectively. Disease incidence differed significantly (P<0.05) among cultivars and years, and was generally greater on Superior and Shepody than on Atlantic and Russet Burbank. This study showed that irrigation may selectively impact tuber disease incidence, depending on treatment and application scheduling, while varying cultivar susceptibility can also impact certain tuber diseases.