Apple Cultivar by Rootstock Trial

In addition to production potential and tree size control, tolerance to environmental stress is an important consideration in selecting an apple rootstock. In Iowa, rootstocks need to exhibit good winter cold tolerance to be considered for use in orchards. In 1992, a cultivar by rootstock study was established at the Western Research and Demonstration (R&D) Farm to evaluate how rootstocks performed on loess soils that are unique to the area. The trial evaluated the performance of three apple cultivars (Smoothee Golden Delicious, Empire, and Nured Jonathan) on seven commercially available rootstocks (seedling, MM.111, MM.106, M.7 EMLA, M.26 EMLA, M.9 EMLA, and Mark) trained to a central leader system. The study was conducted for 10 growing seasons, and the results on growth and production characteristics of the trees were summarized in the 2001 Annual Fruit and Vegetable Progress Report (FG-601) and the 2001 Annual Progress Report for the Western R&D Farm (ISRF01-10). This report summarizes the relative cold tolerance of the cultivars on the seven rootstocks