EFFECTS OF NITROGEN-SOURCES ON DEVELOPMENT OF NETTED SCAB

In a field trial series different nitrogen sources and rates of seed i nfection with netted scab were compared regarding their effects on pla nt development, yield, tuber size distribution and the prevalence of n etted scab in the progeny. Nitrate stimulated netted scab infection in the progeny more than ammonium ions did, although the differences, on average, were moderate. However, in 3 out of 14 trials calcium nitrat e application resulted in a much higher level of netted scab infection in the progeny compared with NPK and ammonium sulphate fertilizers. R easons for the variations in results are discussed.