Severity of potato tubers diseases in treatments with foliar fertilization.

The study was conducted over the years 2004–2006 in experimental plots located in Bałcyny. A multi-purpose, late potato cultivar, Jasia, was grown. The experimental factors were as follows: I – mineral fertilization levels: A (N – 80 kg ha, P – 80 kg ha-1, K – 120 kg ha-1), B (N – 120 kg ha-1, P – 144 kg ha, K – 156 kg ha), II – foliar fertilization: 1 (Basfoliar 12-4-6 – 8 dm ha), 2 (ADOB Mn – 4 dm ha), 3 (Solubor DF – 2 dm ha), 4 (ADOB Mn – 2 dm ha + Basfoliar 12-4-6 – 4 dm ha), 5 (ADOB Mn – 2 dm ha + Solubor DF – 1 dm ha), 6 (Basfoliar 12-4-6 – 4 dm ha + Solubor DF – 1 dm ha), 7 (Basfoliar 12-4-6 – 2.7 dm ha + ADOB Mn – 1.3 dm ha + Solubor DF – 0.7 dm ha), 8 (control treatment without foliar fertilization). The health status of potato tubers was studied after five-month storage. The rates of tuber infection by Streptomyces scabies and Rhizoctonia solani were estimated on 100 tubers selected randomly of particular treatments, according to a nine-point scale, and were presented as a percentage infection index. The symptoms of soft rot (Pectobacterium carotovorum subsp. carotovorum), late blight (Phytophthora infestans) and dry rot (Fusarium spp.) were evaluated in 5 kg samples for each treatment. The results were expressed as a percentage of the mass of infected tubers. Foliar fertilization and the levels of mineral fertilization NPK did not affect the severity of common scab symptoms. Significantly higher rates of infection by R. solani were observed in tubers from the control treatment without foliar fertilization and from the treatment with a lower level of mineral fertilization (A). The symptoms of soft rot (4.6% of the mass of infected tubers) and late blight (1.3%) were strongest in 2006, while the symptoms of dry rot (2.7%) – in 2005. The severity of diseases caused by the above pathogens was greater in tubers grown in plots with a higher level of mineral fertilization (B) – N 120 kg ha, P 144 kg ha, K 156 kg ha (1.3 to 4.1% of the mass of infected tubers) than in tubers grown in plots with a lower level of mineral fertilization (A) – N 80 kg ha, P 80 kg ha-1, K 120 kg ha-1, (0.8 to 3%). The combined application of foliar fertilizers reduced the percentage mass of tubers infected by P. carotovorum subsp. carotovorum and P. infestans to the highest degree. Address: Bożena Cwalina-Ambroziak, University of Warmia and Mazury, ul. Romana Prawocheńskiego 17, 10-720 Olsztyn, phone: +48 (089) 523 41 47, e-mail: bambr@uwm.edu.pl NASILENIE WYBRANYCH CHORÓB BULW ZIEMNIAKA NAWOŻONEGO DOLISTNIE Bożena Cwalina-Ambroziak, Władysław Czajka, Bożena Bogucka 1 Katedra Fitopatologii i Entomologii 2 Katedra Agrotechnologii i Zarządzania Produkcją Roślinną Uniwersytet Warmińsko-Mazurski w Olsztynie S ł o w a k l u c z o w e: bulwy ziemniaka, choroby, nawożenie dolistne, nawożenie mineralne.