Abstract

The main cause of death of walnut plants in Chile is by Phytophthora spp., due to the fact that the most widely used rootstock is Juglans regia, highly susceptible to diseases, with 93% of the orchards located between the regions of Coquimbo and Maule presenting some degree of the disease. The controls applied are of high cost and have limited effectiveness. Starting in 2017, the first clonal rootstocks, RX1, VX211 and Vlach, were introduced in Chile, adding to those that already used Paradox and J. regia. In order to evaluate their performance, two orchards were established, located in the regions of O’Higgins and Coquimbo, where five rootstocks were grafted with ‘Serr’ and ‘Chandler’. The design included eight repetitions and experimental units of three plants each. Four of the replicates were infested with Phytophthora spp. The evaluations began in October 2017. Plant growth and development were evaluated through measurement of shoot length, leaf area, trunk cross-sectional area (TCSA), root growth, floral induction, productivity, and fruit quality. In addition to surviving the infestation. The results from the first five seasons indicated that the VX211, Paradox and Vlach rootstocks have induced greater vigor in the cultivar, which has translated into greater plant development and fruit production cm-2 TCSA. RX1 presents a greater tolerance to water stress, while J. regia in both ‘Serr’ and ‘Chandler’ presented lower development and production and there is no clear effect regarding the infestation with Phytophthora spp. on the development of rootstocks. © 2025 International Society for Horticultural Science. All rights reserved.