Solanum microdontum (PI 558098) develops diagnostic symptoms when inoculated with plant sap containing potato virus A (PVA). The symptoms consist of local lesions (2–4 mm), followed by systemic necrosis of leaf veins, bronzing of leaf surface, and leaf drop. Symptoms develop in a temperature range of 20–29 C with 4 to 8 Klux light intensity of 14 h daylength. Local lesions are visible within 1 wk of inoculation and can be caused by PVA containing sap dilutions of up to 1:100. Plants multiplied by shoot cuttings as well as those produced from true potato seed are equally sensitive. True potato seed production occurs under normal greenhouse conditions in cross-pollinated plants.