S11 - Session P5 - Rootstock resistance to apple replant disease

Authors: Darius Kviklys *

Modern apple growing requires relatively often orchard replacement due to release of superior cultivars or introduction of new growing technologies. Most of intensive apples orchards are established in the same site where apple trees were cultivated for a long period. Continuous cultivation of the same crop often leads to abnormal plant development and decreased productivity what is known as apple replant disease (ARD). Due to ban of chemical soil disinfection, other strategies how to overcome ARD must be developed. Rootstock is becoming to be one of the most important factors to solve this problem and one of the targets of new rootstock breeding programs is rootstock resistance or tolerance to ARD. Different origin and genetic background of rootstocks led to suggest that their adaptiveness to replanted soil will be different. EUFRIN (European fruit research institutes network) Apple and pear cultivar and rootstock testing group established replant trials in several European countries where new apple rootstocks from USA, Great Britain, Poland and Russia are tested. Current paper presents results of the trial performed at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry in 2017-2021. On average of all rootstocks apple trees planted in the fresh soil were by 38% more vigorous and gave 90% higher yield. After the evaluation of tree growth and productivity characters rootstock G.41 was the most tolerant to ARD. Trees on rootstocks G.935, Cepiland-Pajam ® 2 and AR 295-6 had significantly lower yields in replant soil, while tree growth was most stunted on B.10 and AR 295-6.