Rootstocks for peach and nectarine trees in different South African soils

Soil conditions in the stone fruit producing areas of South Africa are extremely varied. Kakamas seedling rootstock has served as mainstay rootstock for many years. Under certain stress conditions (wetness, calcareous soil, root-knot nematodes, and sandy soils) trees on this rootstock show poor growth, small fruit and low yield. A wide range of rootstocks have been evaluated under different soil conditions. 'Alpine' nectarine in a warm area (less than 300 Utah Cold Units) on poor sandy soil, performed significantly better (in terms of yield and fruit size) on Flordaguard compared to Kakamas seedling rootstock. The same cultivar performed excellently in medium potential (17.7% silt and clay), calcareous soil with high numbers of ring nematodes on Atlas, Garnem, Cadaman and Filenem rootstocks. The nectarine 'Artic Star' performed well on high potential (43% silt and clay), calcareous soil with low nematode numbers on Atlas, Viking, Garnem and Monegro rootstocks. Garnem and Cadaman rootstocks grow extremely strong in these soils and need substantial summer pruning. 'Summer Sun' peach trees on high potential replant soil (52% silt and clay) perform well on Atlas and Viking rootstocks. 'Cascade' peach trees on Felinem and Garnem perform well on high potential soil where GF 677 are more prone to infection with fungal diseases. On high risk, sandy soil (5.7% silt and clay) with periodic high-water tables and moderate ring nematodes, 'Summer Sun' peach trees are predisposed to fungal diseases. A high number of dead or dying trees occur on all rootstocks.