Eighth Year Performance of Honeycrisp Grafted on Dwarfing Rootstocks of the NC-140 Regional Apple Rootstock Trial

Abstract

<p>Dwarfing rootstocks have the potential to increase profitability for tree-fruit growers by controlling tree size to allow more trees/acre. Although the initial installation cost can be 10 to 30 times greater than lower-density plantings, the long-range returns can far exceed the traditional plantings. However, to be viable as a commercial rootstock, dwarfing rootstocks must be adapted to a range of agro-climatic conditions, moderately disease resistant, high yielding, and produce quality fruit. To evaluate the adaptability and performance of new and promising apple rootstocks, an NC-140 regional rootstock trial was established in 2010 at 11 sites in the United States (CO, IA, IL, MA, MI, MN, NJ, NY, OH, UT, WI), two sites in Canada (BC, NS), and one site in Mexico (CH) with Honeycrisp apples serving as the test cultivar. Iowa has been evaluating 31 dwarfing rootstocks since 2010 at the ISU Horticulture Research Station, Ames, Iowa. The new selections are from the Cornell-Geneva breeding program (G., CG.), Russia (B.), and Germany (PiAu, Supp.), with M.26 EMLA, M.9 Pajam2, and M.9 T337 serving as industry standards. Tissue cultured propagated (TC) rootstocks of G.41, G.202, and G.935 were included for comparison with normal (N) stool bed propagated rootstocks. This report summarizes the results for the 2017 growing season.</p>