The adoption of high-density orchards over the past decades has resulted in significant improvements in yield and fruit quality. For pear, however, the lack of precocious rootstocks means that full production is often achieved many years after orchard establishment and remains one of the main challenges in pear production. In 2004, one coordinated rootstock field trial was established at two locations in the USA and Canada. The trials compared three Pyrus communisrootstocks: Old Home × Farmingdale (OHF) 97, OHF87 and Pyrodwarf, with 'Taylor's Gold Comice' and 'Concorde' pear as cultivars. After 12 years of growth, trees with OHF97 and OHF87 were the most vigorous under conventional management compared to Pyrodwarf. 'Taylor's Gold Comice' trees on Pyrodwarf rootstocks were 30% smaller than on OHF rootstocks. Cumulative yields were highest from 'Concorde' compared with 'Taylor's Gold Comice'. There were similar values regarding cumulative yield efficiency among the three rootstocks, and fruit size was generally smaller with Pyrodwarf, which also had the most suckers.

A field trial was planted in 2004 at three locations in North America: Geneva, New York, USA; Rockland, Nova Scotia, Canada; and Kentville, Nova Scotia, Canada. The trials compared three Pyrus rootstocks: Old Home x Farmingdale (OHF) 97, OHF87 and Pyrodwarf with 'Taylor's Gold Comice' and 'Concorde' pear as the scion cultivars. After 10 years, 'Concorde' trees at Geneva on OHF97 were the largest while trees on OHF87 and Pyrodwarf were the smaller. At Rockland the same trend was apparent but the differences were not significant while at Kentville, which was an organic site the order of tree size was reversed. With 'Taylor's Gold' OHF87 was generally larger than OHF97. With 'Concorde', cumulative yield at Geneva and Rockland was greatest on OHF97 while at the organic site (Kentville) OHF97 had the lowest yield. With 'Taylor's Gold' there were no significant differences in yield among the tree rootstocks at the three sites. Cumulative yield of 'Taylor's Gold' was very low compared with 'Concorde'. At Geneva, OHF87 had the largest fruit size for 'Concorde' while at Rockland OHF97 had the largest fruit size and at Kentville there were no significant differences in fruit size. With 'Taylor's Gold' OHF87 had the largest fruit size at Geneva while at Rockland both OHF97 and OHF87 had large fruit size. At Kentville there were no differences in fruit size. There were no significant difference in yield efficiency among rootstocks at any of the 3 sites or with either cultivar. Root suckers were highest with Pyrodwarf.

A sweet cherry trial coordinated across North America (the NC140 project) was established in 2010 to integrate precocious rootstocks (of varying vigor levels) with intensive, pedestrian orchard canopy training systems suitable for different regions. The trial sites range from Mexico (Chihuahua/MX) to the United States (California/CA, Colorado/CO, Michigan/MI, Geneva New York/NY-G, New Paltz New York/NY-NP, Ohio/OH) to Canada (British Columbia/BC, Nova Scotia/NS). The rootstocks are Gisela 3 (very dwarfing), Gisela 5 (dwarfing), and Gisela 6 (vigorous), and the scions are 'Benton' (MI, CA, OH), 'Regina' (NY-G, NY-NP), 'Skeena' (BC, NS, MX), and 'Early Robin' (CO). The four intensive training systems under study have the developmental objectives of a) a maximum tree height that permits most orchard work without ladders, b) a tree structure with minimal permanent trunk or scaffold wood, and c) a canopy structure of fruiting wood that is relatively simplified, uniform, renewable, and balanced in leaf-to-fruit ratio. The systems are: 1) Kym Green Bush (KGB), a multiple leader bush with 15 to 20 upright fruiting units; 2) Tall Spindle Axe (TSA), a narrow single leader, with lateral fruiting units; 3) Upright Fruiting Offshoots (UFO), a fruiting wall comprised of an oblique, cordon-like leader with similar to 10 vertically-oriented fruiting units; and 4) Super Slender Axe (SSA), a fruiting wall comprised of closely-planted single leaders with short lateral fruiting units and severe annual pruning. The project objectives are to develop and compare these distinctly different sweet cherry canopy training strategies, determining their developmental and performance interactions with both rootstock and environmental factors (climatic and edaphic). The results reported here represent the initial data from several sites for the orchard establishment phase (Years 1 to 3, planting to initial yield).

Certified organic nutrient sources for apple production in Nova Scotia are limited. Researchers have debated the value of composting manures compared with applying raw manure for various cropping systems. Additionally, it is accepted that fall-applied manure may reduce tree hardiness unless the trees are fully hardened and cool temperatures have greatly reduced soil metabolism. In the Annapolis Valley, uncertified composted and raw poultry manures are readily available. This study compared maintenance and high rates of fall-applied raw cage house or composted cage house poultry manure at rates containing 34, 67, 101, 135 and 168 kg ha(-1) actual N, and a control treatment of no fertilizer on mature 'McIntosh' apple (Malus x domestica) trees. Compared with the trees with no added nutrients, growth, yield and leaf levels of Mn and B increased, while fruit size and hardiness showed no response.

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on the Challenge for a Sustainable Production, Protection and Consumption of Mediterranean Fruits and Nuts ROOTSTOCK TOLERANCE TO APPLE REPLANT DISEASE FOR IMPROVED SUSTAINABILITY OF APPLE PRODUCTION

In early 1970, a breeding program was initiated at Agriculture and AgriFood Canada, Quebec to develop winter hardy rootstocks for cold climates. Seeds harvested in 1975 from controlled crosses between 'Malus robusta R-5' and 'M. 26' or with 'Budagovsky 579490' (B. 490) were germinated under greenhouse conditions, and about 1000 seedlings were subsequently planted in 1980 in a nursery and evaluated. Subsequent orchard evaluation of these rootstocks in several locations within Quebec begun in 1984 resulted in the selection of nine of rootstocks named the St. Jean (SJ84) series: SJP84-5218, SJP84-5217, SJP84-5230, SJP84-5198, SJP84-5162, SJP84-5231, SJP84-5174, SJP84-5189 and SJP84-5180 which were released for commercial evaluation. All of the SJP84 rootstocks are winter hardy, easier to propagate in stool bed compared to 'O.3' and produce a thick and vertical growing sucker in stool bed. No sign of mildew, scab, woolly aphids or incompatibility was observed on these clones.

Leaf photosynthesis of Honeycrisp apple was characterized by gas-exchange measurements using the LCPro+ system (ADC) in order to establish a fully parameterized mechanistic model of leaf photosynthesis for this cultivar. Carboxylation capacity (Vc(max)), electron transport capacity (J(max)), day respiration rate (R-Day), stomatal sensitivity to humidity, CO2 and assimilation (gfac) have been determined from light- and CO2-response measurements on 42 leaves. The leaves were chosen from 6 trees with variable crop loads and differing proportions of leaf zonal chlorosis in order to cover the full range of light exposures, specific leaf weights, shoot types, and chlorotic area of leaf on each tree. The parameterized model was validated using independent photosynthesis measurements with a root mean square error (RMSE) of 11% for photosynthesis and an RMSE of 18% for transpiration. The results show that neither crop load nor shoot type had a significant influence on components of the photosynthetic mechanism while leaf zonal chlorosis reduced photosynthesis rates in proportion to the leaf area affected. Canopy structure above the measured leaf (gap fraction) had by far the biggest effect on leaf photosynthesis rates.

Nine single cultivar replicated trials located in six locations in the states of California, New York, and Washington in the US, Nova Scotia, Canada, and Chihuahua, Mexico were established in 2004 and 2005 as part of the "NC-140 Improving Economic and Environmental Sustainability in Tree-Fruit Production Through Changes in Rootstock Use" project. Rootstocks were grafted to 'Bartlett' ('Williams') in four locations, 'Golden Russet Bosc' in three locations, and 'Concorde' and 'Taylors Gold Comice' in two locations. 'Bartlett' tree spacing ranged from 1.5x3.0 to 2.7x4.6 m, 'GR Bosc' from 1.5x3.0 to 1.8x3.7 m, and 'Concorde' and 'Taylors Gold Comice' was 2.4x4.8 m. Training systems included central leader, vertical trellis and slender spindle. 'Bartlett' was grafted onto 708-36, BM 2000, Horner-4, Fox 11, OHxF 87, Pyrodwarf, and Pyro 2-33 in all four locations. The same rootstocks were included for 'Golden Russet Bosc', however, only Horner 4 and Pyrodwarf were included in all three locations; 'Concorde' and 'Taylors Gold Comice' were grafted to Pyrodwarf, OHxF 87 and OHxF 97. OHxF 69 and 'Winter Nelis' were each included in one 'Bartlett' trial and one 'Golden Russet Bosc' trial also included BU-3. Percent tree survival, trunk cross sectional area (TCSA), fruit yield, number of flower clusters, number of fruit, and number of root suckers were measured and percent set, yield efficiency and average fruit weight were calculated. Percent tree survival and reasons for mortality varied by location and included fire blight and poor vigor. Production data are preliminary, however several trends are notable. Generally, for 'Bartlett', trees on Horner-4 exhibited the largest TCSA but trees on Pyro 2-33, Pyrodwarf, and OHxF 87 performed the best overall across four locations. For 'Golden Russet Bosc', there was no statistical difference between Horner-4 and Pyrodwarf; while trees on Horner-4 generally had the largest TCSA in two of the three trials, OHxF 87 appears to induce better yields and yield efficiency. Cumulative yield efficiencies were equal for 'Concorde' and 'Taylors Gold Comice' on all rootstocks. There was no clear trend in number of suckers, but BM 2000 and Pyrodwarf had the most in some locations. For all rootstock cultivars, fruit weight trends were unclear due to limited data. Formal data collection and reporting will continue through 2014.

In 1999, a trial was established at two sites in Atlantic Canada (Bouctouche, New Brunswick, and Kentville, Nova Scotia) to assess the performance of three semi-dwarf Cornell-Geneva (CG) rootstocks, with three English (M.7 EMLA, M.26, MM.106) and two Polish rootstocks (P 14 and P 60). In NB, the cultivars 'Jonagold' and 'NovaSpy' were examined while a third cultivar, 'McIntosh' was included in NS. The trial was conducted over a period of 7 years (1999-2006) with annual measurements of vigour (trunk-cross sectional area, TCA) and productivity (yield, fruit size, and yield efficiency). CG.052 was similar to P.14 in size controlling, but was significantly less yield efficient. CG.054 was similar in size controlling to MM.106 and M.7EMLA, and also similarly yield efficient with either 'Jonagold' or 'McIntosh'. CG.090 was similar in size and yield efficiency to M.7 EMLA with 'NovaSpy', but with 'McIntosh' they were closer to those on MM.106 in size although less yield efficient.

Trees of 'Honeycrisp' apple (Malus domestica Borkh.) grafted on 24 rootstocks were planted at 1000 trees/ha in 2004 at Bouctouche, NB, Canada (46 degrees 26'N) and grown with and without a three-wire trellis support system. The rootstocks included selections from the M, MM, Budagovsky, Geneva (R), KSC, and V series as well as Alnarp 2, Maruba Kaido, Novole, Ottawa 8, Polish 18 and Yltoinen Piikkio. Trunk cross-sectional area (TCA) was measured yearly while reproductive variables (flowering, fruit size, total and marketable yield) were monitored in 2006 and 2007. The fastest growing trees were on Geneva (R) (G) 30, KSC.6 and KSC.7 and the slowest on Novole, CG.054 and KSC.28. The best overall precocity and yields were from trees on G.30. Other rootstocks showing promise were CG.008, V.1, V.7, M.26Emla and O.8. Very few differences in TCA were noted between supported and non-supported rootstocks. However, supporting trees had a positive impact on precocity which resulted in a two-fold increase in their total yields. High winds in 2007 caused some breakage with most damage occurring to the free-standing trees. The breakage was most prevalent in some rootstocks, notably G.30, CG.090 and V.7.

This study was conducted to evaluate the performance of the apple cultivars ‘Idared’, ‘McIntosh’ (spur type clone, ‘Hartenhoff’) and ‘Fuji’ on hardy semi-dwarf rootstocks (B.490, Y.P., KSC.07, and KSC.18) in comparison to English rootstocks (AR.86-1-25, M.26, MM.106, and MM.111). The trial was conducted over a period of 5 to 10 years in three provinces of Eastern Canada (Quebec, New Brunswick and Nova Scotia). Vegetative (trunk-cross sectional area, TCA) and reproductive traits (yield, fruit size, and yield efficiency) were monitored yearly. The ranking of rootstocks from largest to smallest were KSC.07, Y.P., B.490, KSC.18, MM.106, MM.111, AR.86-1-25 and M.26, and the cultivars ‘Idared’ and ‘McIntosh’ grew larger than ‘Fuji.’ Highest yielding trees were on KSC.07 and Y.P., but only Y.P. was able to maintain good fruit size for all three cultivars over the duration of the trial. Although the objective of this trial was to find a hardy, semi-dwarf rootstock of moderate to low vigour, all hardy rootstocks were found to be larger than any of the English rootstocks.

In spring, 1999, two trials of semi-dwarf apple (Malus x domestica) rootstocks were established under the coordination of the NC-140 Technical Committee. One trial included 'Fuji' as the scion cultivar, and the other included 'McIntosh'. Rootstocks were CG.4814, CG.7707, Geneva (R) (G) 30N (liners from stool beds), M.7 EMLA, M.26 EMLA, and Supporter 4. The 'Fuji' trial was planted in Kentucky, Missouri, and North Carolina, with a partial planting in South Carolina. The 'McIntosh' trial was planted in Massachusetts, Michigan, Minnesota, Nova Scotia, New York (Williamson), and Ontario, with partial plantings in New York (Peru), Pennsylvania (Rock Springs), and Vermont. Trees were spaced 4x6 m and trained as free-standing central leaders. 'Fuji' trees on M.7 EMLA had larger trunk cross-sectional area in 2007 than those on Supporter 4. 'McIntosh' trees on M.7 EMLA and Supporter 4 were larger than those on M.26 EMLA, CG.4814, or CG.7707. Root suckering (cumulative, 1999-2007) was much more prominent with 'Fuji' as the scion cultivar than with 'McIntosh'. M.7 EMLA resulted in the most root suckering with both scion cultivars, and M.26 EMLA resulted in the least. Cumulatively (2001-07), 'Fuji' trees on G.30N yielded more than those on M.26 EMLA, CG.4814, M.7 EMLA, or Supporter 4. 'McIntosh' trees on G.30N, Supporter 4, M.7 EMLA, and CG.4814 yielded more than those on M.26 EMLA. Cumulatively (2001-07), 'Fuji' trees on G.30N and Supporter 4 were more yield efficient than those on M.7 EMLA. For 'McIntosh', however, trees on CG.4814 were more yield efficient than all others, and trees on G.30N and CG.7707 were more efficient than those on M.7 EMLA. On average over the fruiting life of the trial (200107), fruit size was not affected by rootstock for either cultivar.

Apple trees grown under Nova Scotia's uniquely short, cool season conditions, tend to be about 25% smaller than trees grown in many other apple growing areas in North America. Local rootstock research as well as ad hoc field investigations in Nova Scotia's Annapolis Valley, have pointed to opportunities for the use of rootstocks in the semi-dwarfing to semi-vigorous range. In this study, the performance Geneva (R) 30 (G.30) apple (M. domestica Borkh.) rootstock was evaluated at four grower sites within the Annapolis Valley of Nova Scotia, over a period of 6 years. In Kingston and Rockland, G.30 was compared with the traditional rootstocks M.26 and MM.106 using 'Jonagold' as scion cultivar, in Morristown G.30 was compared with M.26 and M.7 using 'Royal Cort' and in Blomidon, G.30 was compared with M.26 and M.7 using 'Northern Spy'. At all sites, G.30 was found to be as vigorous as MM.106 and M.7 and approximately 30% larger than M.26 when trunk cross-sectional area was used as an index of canopy size. In addition, G.30 exhibited the early bearing characteristic trait of M.26, but ultimately out-yielded this rootstock at all four sites. At the Blomidon site, G.30 showed itself to be far superior to M.7 both with regard to early bearing as well as cumulative yield of 'Northern Spy', a cultivar known for it's long transitional phase and biennial tendencies. This rootstock can be recommended as a replacement for M.26 on droughty soils in the Annapolis Valley where it can be expected to produce a medium size tree. In more vigorous situations, it may well prove too robust for higher density plantings.

Tree fruit growers use chemical and mechanical thinning techniques in an attempt to maintain regular annual flower production and maximum repeatable yields of varieties susceptible to biennial bearing. If the percentage of floral buds an apple tree could produce without causing yield depression in subsequent years was known, it would be possible to better manage crop-thinning regimes. This study proposes that thinning is a partial transfer of potential flower buds from one year to the next year and estimates the maximum repeatable sequence of flower buds without biennial bearing. The conceptual framework is tested on a 50-year simulation with 0% to 100% transfer of thinned flower buds. Results indicate that the maximum repeatable sequence of flower buds rises sharply when the final years of the orchard approach and declines when the percent transfer of thinned buds is near 0%.

Kentville Agricultural Research Centre, Agriculture & Agri-Food Canada, 32 Main Road, Kentville, NS, B4N 1J5, Canada School of Environmental Science, University of Guelph, Guelph, ON, N1G 2W1, Canada Crops and Livestock Research Centre, Agriculture & Agri-Food Canada, 440 University Avenue, Charlottetown, PE, C1A 4N6, Canada Nova Scotia Agricultural College, PO Box, 550, Truro, NS, B2N 5E3, Canada AgraPoint, Kentville, NS, B4N 1H7, Canada

In 1960, a breeding program was initiated in Morden, Manitoba, Canada to develop winter hardy rootstocks for northern cold climates. Later the program was transferred to the Agriculture and Agri-Food Canada (AAFC), Horticulture Research and Development Center (HRDC), at St-Jean-sur-Richelieu, Quebec. Two hundred and nine seedlings were selected from the initial population and since 1970 have been evaluated at the AAFC-HRDC, Quebec, Canada. Seven of these selections (SJM15, SJM44, SJM127, SJM150, SJM167, SJM188 and SJM189) obtained from crossing 'Nertchinsk' with M. 9 and M. 26 were found to be winter hardy, disease resistant, dwarfing, yield efficient and easier to propagate than O.3 and were released for commercial evaluation in 2005.

O3A is a new rootstock resulting from a mutation in an Ottawa 3 (O.3) stool bed discovered at the Agriculture and Agri-Food Canada (AAFC) Research Station, St-Jean-sur-Richelieu, Quebec. It produces dwarf trees equal in size to O.3 but with better precocity (early fruiting), higher yield efficiency (based on yield/trunk cross sectional area), fewer suckers and wider branch angles. O3A is similar to O.3 in susceptibility to two races of Erwinia amylovora (Burrill) Winslow and four isolates of Phytophthora cactorum (Leb. & Cohn) Schroet).