Good Fruit Grower

www.goodfruit.com GOOD FRUIT GROWER JULY 2017 25 survival across all sites. Root suckering was only a prob- lem with P. americana, which had excessive root sprouts under the trees. Largest trees were three Prunus x almond hybrids and Guardian. Fruit size varied with location and crop load (i.e., some rootstocks had few fruit). KV010127 produced the largest fruit and Controller 5 and Mirobac (aka Replantpac) the smallest fruit across all sites. Cumulative yields were generally highest with the peach rootstocks, with Guardian leading the way. Lowest yields were from plum hybrids and species. Cumulative yield efficiency was highest on the nonpeach rootstocks, including many of the plum hybrids or species. However, many of these rootstocks produced trees much smaller than the peach and almond hybrid cultivars. These data suggest there were no demonstrated advantages to using clonal interspecific Prunus hybrids for peach production under current cultural practices." 2017 NC-140 Peach Systems Rootstock Trial What's clear from the research so far is that peach rootstocks perform very differently throughout the U.S., and needs vary as well. The Southeast needs disease resistance, while the Northeast and Michigan require cold hardiness. And everyone needs dwarfing rootstocks that are well tested and vetted. To continue this effort, a new NC-140 research trial got underway in spring 2017, with seven rootstock vari- eties planted at 10 locations in North America — nine states and one Canadian province. They are: —Controller 6 (HBOK 27), Controller 7 (HBOK 32) and Controller 8 (HBOK10), all from the University of California, Davis. —Rootpac 20 (Nano Pac) and Rootpac 40 (Densi Pac), both from Agromillora Catalana, Spain. —MP-29 from breeder Tom Beckman, U.S. Department of Agriculture, Byron, Georgia. MP-29 is a clonal plum-peach interspecific hybrid that was released in 2011. It is resistant to PTSL, ARR and root-knot nematodes. The cultivar Cresthaven was used, and rootstocks Guardian and Lovell were planted as controls. All trees were planted at a spacing of 5.9 feet by 18 feet with a perpendicular-V as the training system. Evaluating these more dwarfing rootstocks in a closer-spaced system will allow us to better evaluate them in a more modern, high- er-density production system. States included in the 2017 trial include Colorado, Georgia, Alabama, South Carolina, North Carolina, Pennsylvania, New York, Utah, Michigan and California. For more information on the 2009 trial and how spe- cific rootstocks performed in specific locations, NC-140 or publications, visit www.nc140.org:8000/Login (anyone can log in as a guest using the anonymous login). The NC-140 website is maintained by Jon Clements of the University of Massachusetts and Win Cowgill. • Win Cowgill is professor emeritus at Rutgers University and CEO of Win Enterprises International, LLC, a pomology and horticultural consulting group working with commercial growers and nurseries. He can be reached at wincowgill@mac.com. Sources: MA, SC, NC, UT- 2015 NC140 State Reports @ http://nc140.org/ NC-140 multi-state research project: Improving economic and environmental sustainability in tree-fruit production through changes in rootstock use. Winfred P. Cowgill, Jr., Wesley R. Autio, Emily E. Hoover, Richard P. Marini, and Paul A. Domoto 2017. J Am Pom Soc. (APS) 71:34-46. http://www. pubhort.org/aps/71/v71_n1_a5.htm Performance of Prunus rootstocks in the 2001 NC-140 peach trial. Reighard, G.L., Beckman, T.G., Belding, R., Black, B.L., Cline, J., Cowgill, W., Godin, R., Johnson, R.S., Kamas, J., Kaps, M., Larsen, H., Lindstrom, T., Ouellette, D., Pokharel, R., Stein, L., Taylor, K., Walsh, C.S., Ward, D. and Whiting, M.D. (2011). Acta Hortic. 903, 463-468. DOI: 10.17660/ActaHortic.2011.903.63 Evaluating Potential Peach Rootstocks in the NC-140 Trial Cling Peach Report 2013-14, http:// calclingpeach.com/peach-research/ Johnson, Day, Dejong, Beckman, T.G., Okie, W.R., Nyczepir, A.P., Reighard, G.L., Zehr, E.I. and Newall, W.C. 1997. History, Current Status and Future Potential of Guardian (BY 520-9) Peach Rootstock. Acta Hort. (ISHS) 451:251-258 http://www.actahort.org/books/451/451_27.htm Evaluation of Peach Rootstocks: 2009 NC-140 Peach Rootstock Trial through Seven Growing Seasons. Wesley R. Autio, James S. Krupa, Jon M. Clements, and Winfred P. Cowgill, Jr. Fruit Notes, Volume 81, Summer 2016. http://www.umassfruitnotes.com/v81n3/wxyzCover813.html Evaluating Potential Peach Rootstocks in the NC-140 Trial. Cling Peach Report 2013-14, http:// calclingpeach.com/peach-research/ Johnson, Day, Dejong. Peach Rootstock Trials: A 2014 Update. A report to the State Horticultural Association of Pennsylvania, 2014 Research Grant. Jim Schupp. http://shaponline.org/

• Cover