Occurrence of common scab in potato tubers after foliar treatment with glycinebetaine under glasshouse conditions

Authors

• Elina Tuomola Department of Plant Production, P.O. Box 27, FIN-00014 University of Helsinki, Finland
• Hannu Rita Department of Forest Resource Management/Statistics, PO. Box 24. FIN-00014 University of Helsinki, Finland
• Paavo Kuisma Potato Research Institute, Ruosuontie 156, FIN-16900 Lammi, Finland
• Susanne Somersalo Department of Plant Production, PO. Box 27, FIN-00014 University of Helsinki, Finland
• Eija Pehu Department of Plant Production, PO. Box 27, FIN-00014 University of Helsinki, Finland
• Kari Jokinen Cultor Ltd., Finnsugar Bioproducts, PO. Box 105, FIN-00241 Helsinki, Finland
• Jari P. T. Valkonen Department of Plant Production, PO. Box 27, FIN-00014 University of Helsinki, Finland

DOI: https://doi.org/10.23986/afsci.72773

Abstract

A single foliar spray with 2.5 mM glycinebetaine (GB) was applied on potato (Solatium tuberosum L.) cvs. Matilda, Sabina and Saturna grown in a sand bed infested with Streplomyces scabies (Thaxter) Waksman & Henrici at tuber initiation. A period of drought was maintained after GB treatment to enhance scab infection. Logit models were used to compare scab incidence in all harvested tubers (n = 622) and the type of scab in the symptomatic tubers (n = 382), whereas the tuber surface areas covered with scab lesions were compared using ANOVA. A 10 g increase in tuber weight increased the odds of scab incidence by 11.3%. Scab incidence was lowest in Sabina and highest in Matilda. Raised scab and superficial scab were common in all cultivars, but pitted scab developed only in a few tubers of Sabina and Matilda. Among the scabby tubers, the incidence of raised scab was highest in Sabina and lowest in Saturna. The mean surface area covered with scab was 32.8% in Matilda, 11.7% in Saturna and 7.5% in Sabina. Treatment with GB slightly reduced the severity of scab symptoms, as shown by the reduction in the proportion of tubers with raised scab among the scabby tubers (odds 0.60). No effect on the incidence of scab or the tuber area covered with scab lesions was detected following GB treatment.