EFFECT OF IRRIGATION AND DIFFERENT NITROGEN FERTILIZATION RATES ON THE OCCURRENCE OF STREPTOMYCES SCABIES (TAXTER) ON POTATO CULTIVATED ON VERY LIGHT SOIL

摘要

From 1986 to 1994 the effect of different nitrogen fertilisation rates and irrigation on the occurrence of Streptomyces scabies on tubers of potato cultivated on very light soil was investigated. Four Polish varieties were used: Mila, Cisa, Jasmin andDrop. Irrigation time and water doses were determined according to tensiometric measurements and depended on weather conditions during the growing season. Because very low retention ability of the soil, water was applied in small doses. In years with low rainfall during the growing season, water irrigation increased the infection of potato tubers by S. scabies. In years with average rainfall for central Poland, irrigation had no effect on tuber infection. Nitrogen fertilisation did not influence infection by the pathogen, irrespectively of water irrigation.