Double Setting of Potato Seed Tubers as a New Approach to Research Primary Stem Blight (Phytophthora infestans (Mont.) de Bary)

Abstract

The double setting of two seed tubers is introduced as a new method for research on primary stem blight of potato, Solanum tuberosum L. caused by Phytophthora infestans (Mont.) de Bary). The principal focus of this experimental layout is the planting of a healthy seed tuber adjacent to an inoculated one, termed double setting. The infected tuber serves as a source of inoculum, enabling the disease to spread to the neighboring plant, where stem infections occur. The new method was compared to the common procedure of direct inoculation of tubers. The rate of emergence using double setting was significantly higher compared to direct inoculation. Additionally, stem blight was more intense and generally occurred earlier. Direct inoculation proved to be less suitable for research where the occurrence of higher percentages of stem blight symptoms is necessary. Further more, the double setting method generally permits insight into the spread of the disease from latent infected tubers to healthy ones under the natural conditions within the potato hill.