Apple rootstock research Emily Hoover Professor, Department of Horticultural Science University of Minnesota Total Acres in Orchards 2002 www.nass.usda.gov/research/atlas02/index.html The #1 reason for fewer orchards in Minnesota? Winter injury Stunted growth Dead trees Split bark USDA Hardiness Zone Map http://www.usna.usda.gov/Hardzone/hzm-nm1.html Zone Fahrenheit Celsius Example Cities 2a -50 to -45 F -42.8 to -45.5 C Prudhoe Bay, Alaska; Flin Flon, Manitoba 2b -45 to -40 F -40.0 to -42.7 C Unalakleet, Alaska; Pinecreek, MN 3a -40 to -35 F -37.3 to -39.9 C International Falls, MN; St. Michael, Alaska 3b -35 to -30 F -34.5 to -37.2 C Duluth MN; Sidney, Montana 4a -30 to -25 F -31.7 to -34.4 C Minneapolis/St.Paul, MN; Lewistown, Montana 4b -25 to -20 F -28.9 to -31.6 C La Crescent MN; Nebraska 5a -20 to -15 F -26.2 to -28.8 C Des Moines, Iowa; Illinois Orchards around 1890 Orchards today Why rootstocks? Impart characteristics to scion (cultivar) –Size control – Uniformity in tree size – Precocity, earliness to flower – Tolerance to cold temperatures – Resistance to soil borne pests and diseases – Increase in fruit size and quality Major Apple Rootstock Programs • East Malling England (M, MM, EMLA) • Poland (P) • Russia (B, Bud) - Budagovsky series • Canada - Robusta 5, Ottawa (Ott) and Vineland (V) • United States Cornell-USDA Geneva NY (CG, G) • Germany (Supp) Regional Research Group – NC140 • To evaluate the influence of rootstocks on fruit tree characteristics • To develop and improve rootstocks for temperate-zone fruit trees • To study the genetics and developmental physiology of rootstock/scion interactions • To better understand the response to and impacts of biotic and abiotic stresses NC-140 Locations Minnesota is the location with the coldest winter temperatures Apple Rootstocks Evaluated in MN • Malling Series (England) – 4, 7, 9, 26, 106, 111 • Poland – 1, 2, 16, 18, 22 • Budagovsky series – 9, 490, 491 • Canada - Vineland 1, 3; Ott 3 • Geneva series – 10, 11, 24, 29, 30N,30T, 65, 202, 210, 935,814, 7707, • Michigan – MARK, MAC 1 and 39 Data Collected • Tree survival • Tree characteristics – Trunk cross sectional area – Height and spread – Shoot growth – Branch angle – Trunk leaning – Burr knots • Yield – # flower clusters (first 2 years) – Total kg/tree –Fruit wt How Minnesota Compares • Trees are smaller than most NC140 locations • Cultivar is important! • Harvest is delayed 2 to 3 years • Yield is lower Rootstock TCA Yield Yield efficiency (cm2) (kg) (g/cm2) CG935 25.7a 11.7a 483.1a Supp 3 18.2abc 9.7a 542.1a Supp 2 17.9abc 6.6a 512.3a Supp1 12.8bc 4.7a 372.3a Interested in the M26 12.8bc 4.7a 319.1a M9 12.0c 3.6a 312.3a relationship between tree Growth (cm) of 1-year shoots of McIntosh grown on various growth (TCA rootstocks, 4th leaf and shoot growth) and CG935 SUPP3 dwarfing SUPP2 SUPP1 M26 M9 0 5 10 15 20 25 30 35 40 45 Questions?.