2018 ASHS Annual Conference

Aronia is a novel fruit crop that produces black fruits that are one of the richest sources of dietary polyphenols and anthocyanins. Aronia grows as a multistemmed shrub with many basal shoots. Aronia berries are machine harvested commercially, but low branches laden with fruit are missed by harvesters resulting in 20 to 30% loss of harvest. The low branching also makes weed management difficult. We studied the compatibility and performance of Aronia mitschurinii ‘Viking’ grafted onto various tree rootstocks in the Pyrinae including Crataegus laevigata, Pyrus communis, Sorbus alnifolia and Sorbus aucuparia in comparison to own-root cutting plants. Chip bud grafting was used and scions were grafted at 15cm and also at 60 cm for Sorbus aucuparia. Best grafting success occurred with S. aucuparia at over 85%, while Crataegus had the lowest success rate at 33%. Success with Pyrus and S. alnifolia was ~50%. Significant losses of grafts on Pyrus and Crataegus occurred in the second and third growing seasons, while no losses occurred with Sorbus rootstocks. Plants grafted onto S. aucuparia were larger and produced more shoot growth than any other rootstock species or own-root plants. Plants grafted onto Sorbus rootstocks yielded substantially more fruit than own-root plants or plants with Crataegus or Pyrus rootstocks. S. aucuparia produced about three times as much fruit as own-root plants and produced substantial yields at an earlier age than own-root plants. Mineral nutrient content of foliage and fruits were analyzed but did not show biologically significant differences between different rootstocks and own root plants. Some statistical differences were seen for fruit Brix and titratable acidity between study plants, but the differences are not significant as far as fruit quality is concerned. A. mitschurinii ‘Viking’ grafted at 60 cm high produced plants with architecture where all branches were held erect and well above the ground. These high grafted plants would allow mechanical harvesters to completely pick all fruit from the plants. Weed control, either by mechanical or herbicide applications, would be easy with the high grafted plants. Crataegus and Pyrus are not suitable species for use as rootstocks with Aronia. Sorbus, especially S. aucuparia, is an ideal rootstock for use with Aronia.