Two newly released South African potato cultivars, Frodo and Darius, were compared with two foreign processing cultivars, Pentland Dell and Shepody. The cultivars were grown under sprinkler irrigation and evaluated for external and internal tuber characteristics and processing quality. The experiment was conducted at Bronkhorstspruit, South Africa. Results indicated that Frodo had significantly higher tuber form index values (long tuber shape) for all tuber sizes, a desired characteristic for french fry processing. Pentland Dell and Shepody exhibited
more vascular discolouration, while Frodo had the highest occurrence of tuber brown spot. These physiological disorders probably resulted from unfavourably high temperatures and water stress during the late growing season. Shepody had the lowest specific gravity, followed by Pentland Dell. Reducing sugar levels for both the foreign cultivars were also relatively high and only marginally within the ranges required for french fry processing. Frodo and Darius, on the other hand, had high specific gravities and low reducing sugar levels, which are desirable characteristics for long-term storability and the production of quality frozen fries. Tuber yields of these two cultivars were also similar or higher than those of the foreign cultivars. Frodo and Darius can, therefore, successfully compete with Shepody and Pentland Dell as processing cultivars under local conditions.