Source: N Y AGRICULTURAL EXPT STATION submitted to
ROOTSTOCK AND INTERSTEM EFFECTS OF POME AND STONE FRUIT TREES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0073725
Grant No.
(N/A)
Project No.
NYG-632484
Proposal No.
(N/A)
Multistate No.
NC-140
Program Code
(N/A)
Project Start Date
Oct 1, 2002
Project End Date
Sep 30, 2007
Grant Year
(N/A)
Project Director
Robinson, T. L.
Recipient Organization
N Y AGRICULTURAL EXPT STATION
(N/A)
GENEVA,NY 14456
Performing Department
GENEVA - HORTICULTURAL SCIENCES
Non Technical Summary
Pome and stone fruit growers who want to stay profitable must establish high-density plantings with much smaller trees. The rootstock is the central component of high-density systems. New rootstocks cannot be recommended to commercial growers until they have been tested in a variety of soils and climates for 8-10 years. The NC-140 project seeks to rapidly test pome and stone fruit rootstock in a variety of climates and to understand rootstock performance and limitations. The NC-140 plantings are regularly used as demonstration plots of new and future rootstocks for growers.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2011110108030%
2051110102030%
2051112108010%
2051114108010%
2051115108010%
2051116108010%
Goals / Objectives
1. To evaluate the field performance of pome- and stone-fruit rootstocks in various environments and under different management systems, and to optimize experimental design for such evaluations. 2. To assess and improve asexual propagation techniques of pome- and stone-fruit rootstocks. 3. To develop and improve pome- and stone-fruit rootstocks through breeding and genetic engineering, and to acquire new rootstocks from worldwide sources. 4. To understand the developmental and abiotic stress physiology of rootstock/scion interactions in pome- and stone-fruit trees.
Project Methods
Promising new and existing rootstocks and multiple genetic systems possessing desirable characteristics will be selected and evaluated with respect to precocity, productivity, size control, anchorage, suckering, pest resistance, adaptability, and production efficiency through replicated and randomized uniform trials in different climatic and edaphic environments. These trials will be maintained and data will be collected according to specific uniform guidelines established by the technical committee. Data will be summarized for joint publications after five and 10 years of testing. Currently we have 5 apple rootstock trials (1993, 1994. 1998, 1999, and 2002), one sweet cherry rootstock trial (1998), and a peach rootstock trial (2002). New apple trials are planned for 2003 and 2006. A new pear trial is planned for 2004 and a new cherry trial is planned for 2005. Additional trials will be conducted across New York State on growers farms to demonstrate superior rootstocks to growers. Laboratory, greenhouse, and field studies will evaluate the propagation characteristics of existing and new rootstocks and develop improved means of asexual propagation through improved tissue-culture techniques and improved stoolbed-propagation strategies. Rootstock identification will be studied by the use of isozyme analysis and randomly amplified polymorphic DNAs to identify rootstocks. A rootstock breeding programs will develop improved rootstocks for apple that are tolerant to pathogenic organisms such as fire blight, crown rot, latent viruses, lesion nematode, and specific apple replant disease by conventional breeding techniques and molecular genetic techniques in cooperation with the USDA. Further, gene mapping will identify markers for genes controlling dwarfing, precocity, yield efficiency and pest resistance. Genetic engineering techniques will be used to insert genes into existing rootstocks to improve pest resistance. Other rootstocks from breeding programs around the world will be acquired for evaluation. Physiological studies of rootstock-induced changes in scion physiology will be conducted to better understand altered carbon partitioning, cold hardiness of rootstocks and the influence of rootstock on scion cold hardiness for apple, the periodicity of root growth of apple rootstocks, moisture stress tolerance of apple rootstocks and graft-union strength of apple rootstocks.

Progress 10/01/02 to 09/30/07

Outputs
OUTPUTS: A series of replicated field trials were established in New York State in 2002 to evaluate rootstocks for European and Japaneese plums. In a field trial with Empress plum, the highest cumulative yield was with Cadaman followed by Ishtara, Jaspi, Torinel, GF8-1, VVA-1 and Penta which had the lowest yield. Jaspi and VVA-1 were significantly less vigorous than the other 5. Cumulative yield efficiency was greatest with Jaspi followed by Ishtara, Cadaman, Torinel, GF8-1, VVA-1 and Penta. Although Jaspi had the highest yield efficiency it also had the most suckers. The best stock appears to be Ishtara. In a second field trial, Ishtara was the most vigorous stock followed by GF8-1, Cadaman, American Plum, Penta Torinel, Jaspi, and VVA-1 which is the least vigorous stock. VVA-1 along with Torinel and Jaspi are much less vigorous. Yield efficiency was greatest with VVA-1, Ishtara, Jaspi and American Plum. Suckering was least with Ishtara and Penta while all of the other stocks had considerable suckering. With Japanese plums VVA-1 is the best but has suckering. Ishtara has high yield and low suckering. In a third rootstock trial with Obilinaja Plum which is cross between P. salacina x P. cerasifera. The most vigorous stock after 6 years was Mariana GF 8-1 followed by Ishtara, Cadaman, Penta, Jaspi, Torinel, and VVA-1, respectively. Yield was highest with Cadaman followed by Jaspi, Ishtara, Torinel, GF8-1, Penta, VVA-1 which had the lowest yield. Yield efficiency was highest with Cadaman, followed by Jaspi, Torinel, Ishtara, GF8-1, Penta and VVA-1 respectively. Suckering was high for Jaspi, Torinel and Penta while suckering was low with Ishtara and Cadaman. GF8-1 It is disappointing that VVA-1 has not performed better. It appears that Cadaman, Jaspi and Ishtara are the best stocks with Oblinaya. PARTICIPANTS: Terence L. Robinson, Associate Professor, Dept. of Hort. Sciences, NYSAES, Cornell University, Geneva, NY 14456 Herb Aldwinckle, Professor, Dept. of Plant Pathology, NYSAES, Cornell University, Geneva, NY 14456 Steve Hoying, Senior Research Associate, Dept. of Hort. Sciences, NYSAES, Cornell University, Geneva, NY 14456 Gennaro Fazio, Scientist, USDA/ARS Plant Genetics Resources Unit, NYSAES, Cornell University, Geneva, NY 14456 Jason Osborne, Extension Associate, Cornell Cooperative Extension, Newark, NY TARGET AUDIENCES: The commercial apple, peach, cherry, pear, plum and apricot growers of NY state and the northeastern USA are the primary target audience of this project. Other fruit growers in the USA, Canada, Mexico, South America, Europe, Asia and Africa are also target audiences.

Impacts
The search for new well adapted and dwarfing plum rootstocks has preliminarily identified several new stocks which are more productive and efficient that Myrobolan but are not more dwarfing. These should provide plum growers with improved choices for rootstocks when planting new orchards.

Publications

  • Russo, N., T.L. Robinson, H.S. Aldwinckle and G. Fazio. 2007. Horticultural performance and fire blight resistance of Cornell-Geneva apple rootstocks and other rootstocks from around the world. HortScience 42:1517-1525.
  • Russo N. L., T. L. Robinson, G. Fazio and H.S. Aldwinckle. 2007. Evaluation of apple rootstocks for resistance to fire blight and orchard performance. Proceedings of the 2007 Great Lakes Fruit Workers Meeting Abstracts p.68.
  • Autio W., L. Anderson, B. Barritt, J. Cline, R. Crassweller, C. Embree, D. Ferree, E. Garcia, G. Greene, E. Hoover, S. Johnson, K. Kosola, J. Masabni, M. Parker, R. Perry, G. Reighard, T. Robinson. 2007. Early performance of 'Fuji' and 'McIntosh' apple trees on several dwarf rootstocks in the 1999 NC-140 rootstock trial. Acta Hort. 732:119-126.
  • Autio W., L. Anderson, B. Barritt, J. Cline, R. Crassweller, C. Embree, D. Ferree, E. Garcia, G. Greene, E. Hoover, S. Johnson, K. Kosola, J. Masabni, M. Parker, R. Perry, G. Reighard, T. Robinson. 2007. Early performance of 'Fuji' and 'McIntosh' apple trees on several semidwarf rootstocks in the 1999 NC-140 rootstock trial. Acta Hort. 732:127-134.
  • Masabni, J.G., P. Hirst, G. Brown, D. Wolfe, R. Perry, R. Andersen, J. Freer, T. Robinson, A. Azarenko, E. Mielke, B. McCluskey, G. Tehrani and W. Lay. 2007. Performance of plum rootstocks with Stanley, Valor, and Veeblue as the scion in the 1990 NC-140 multi-location plum trial. Journal of the American Pomological Society 61:196-207.
  • Robinson, T.L. 2007. Performance of pear and quince rootstocks with three cultivars in four high density training systems in the Northeastern United States. 10th Int. Pear Symposium Programme and Abstracts p. 73.)
  • Robinson, T.L., R.L. Andersen and S.A. Hoying. 2007. Performance of six high density cherry training systems in the northeastern United States. Acta Hort. 732:421-428.
  • Robinson, T.. L. Anderson, W. Autio, B. Barritt, J. Cline, R. Crassweller, W. Cowgill, C. Embree, D. Ferree, E. Garcia, G. Greene, C. Hampson, K. Kosola, M. Parker, R. Perry, T. Roper and M. Warmund. 2007. A multi-location comparison of Geneva 16, Geneva 41 and M.9 apple rootstocks across North America. Acta Hort. 732:59-66.
  • Russo N. L., H.S. Aldwinckle, T. L. Robinson and G. Fazio. 2007. Budagovsky 9 rootstock: Uncovering a novel resistance to fire blight. Int. Fire Blight Symposium Programme and Abstracts p.)


Progress 01/01/06 to 12/31/06

Outputs
A series of replicated trials in New York State were established in 1998- 2002 to evaluate the Cornell-Geneva series of apple rootstocks which have been bred for resistance to fire blight and Phytophthora root rot, high yield efficiency and good tree survival. Among dwarfing rootstock candidates that are similar in size to M.9, Geneva 41 (G.41), G.11 and G.16 have shown the greatest yield efficiency and have equaled or exceeded the performance of M.9. G.41 has shown a high level of resistance to fire blight and has also shown good cold hardiness in test winters while G.11 has shown a moderate level of resistance to firelight. G.16 showed significantly greater winter survival than M.9, M.26 or B.9 in a mid-winter freeze event in 2004 but greater tree damage than M.9 from an late fall freeze in 2003. Among semi-dwarfing rootstock candidates that are similar in size to M.26, both G.935, and G.202 have been significantly greater yield efficiency than M.26. In addition, they both have shown high resistance to fire blight and good tolerance to apple replant disease. Both have shown good winter survival to midwinter cold events.

Impacts
The introduction of 3 disease resistant Geneva rootstocks has been met with considerable interest among growers all over the world. In the US the largest fruit tree nurseries have begun propagating these stocks and they are slowly increasing their production. US and Canadian apple growers have begun planting new orchards with these rootstocks as fast as they can afford the high cost of replanting an orchard. The economic impact of these stocks is similar to the value of insurance. If a young dwarf orchard is devastated by fire blight it can cost the grower $10,000-20,000 per acre to replant. The GenevaTM rootstocks offer insurance against a sporadic but devastating disease.

Publications

  • Autio, W.R., T.L. Robinson, B.H. Barritt, J.A. Cline, R.M. Crassweller, C.G. Embree, D.C. Ferree, M.E. Garcia, G.M. Greene, E.E. Hoover, R.S. Johnson, K. Kosola, J. Masabni, M.L. Parker, R.L Perry, G.L. Reighard, S.D. Seeley and M. Warmund. 2006. Comparison of several semidwarf rootstocks with Fuji and McIntosh as cultivars: 1999 NC140 semidwarf apple rootstock trials. Compact Fruit Tree 39(2):24-27.
  • Autio, W.R., T.L. Robinson, B.H. Barritt, J.A. Cline, R.M. Crassweller, C.G. Embree, D.C. Ferree, M.E. Garcia, G.M. Greene, E.E. Hoover, R.S. Johnson, K. Kosola, J. Masabni, M.L. Parker, R.L. Perry, G.L. Reighard, S.D. Seeley and M. Warmund. 2006. Comparison of several dwarf rootstocks with Fuji and McIntosh as cultivars: 1999 NC140 semidwarf apple rootstock trials. Compact Fruit Tree 39(2):28-32.
  • Carroll, J.E., T.L. Robinson, D.I. Breth, S.A. Hoying, A.N. Lakso, A.M. Agnello, A.J. Landers, J.P. Nyrop, W.H. Reissig, R.W. Straub, M.J. Fargione, P.D. Curtis, D.A. Rosenberger, K.A. Iungerman, L. Cheng, I. A. Merwin and C.B. Watkins. 2006. New York integrated fruit production protocol for apples. New York Food and Life Sciences Bulletin 158, Cornell University, Geneva, NY.
  • Fazio, G., H.S. Aldwinckle, R.P. McQuinn and T.L. Robinson. 2006. Differential susceptibility to fire blight in commercial and experimental apple rootstock cultivars. Acta Hort. 704:527-530.
  • Hoying, S.A. and T.L. Robinson. 2006. The vertical axis apple planting system. http://www.theorchardkeeper.blogspot.com/
  • LoGiudice, N., H.S. Aldwinckle, T.L. Robinson and G. Fazio. 2006. The nature of resistance of the B.9 apple rootstock to fire blight. Acta Hort. 704:515-520.
  • Marini, R.P., J.L. Anderson, J.A. Barden, B.H. Barritt, G.R. Brown, J. Cline, W.P. Cowgill, Jr., P.A. Domoto, D.C. Ferree, R.M. Garner, G.M. Greene, C. Hampson, P. Hirst, M.M. Kushad, J. Masabni, E. Mielke, R. Moran, C.A. Mullins, M. Parker, R.L. Perry, J.P. Prive, G.L. Reighard, T. Robinson, C.R. Rom, T. Roper, J.R. Schupp, E. Stover and R. Unrath. 2006. Performance of Gala on four semi-dwarf rootstocks: A ten-year summary of the 1994 NC-140 semi-dwarf rootstock trial. Journal of the American Pomological Society 60:58-68
  • Marini, R.P., J.L. Anderson, W.R. Autio, B.H. Barritt, J. Cline, W.P. Cowgill, Jr., R.M. Garner, A. Gauss, R. Godin, G.M. Greene, C. Hampson, P. Hirst, M.M. Kushad, E. Mielke, R. Moran, C.A. Mullins, M. Parker, R.L. Perry, J.P. Prive, G.L. Reighard, T. Robinson, C.R. Rom, T. Roper, J.R. Schupp, E. Stover and R. Unrath. 2006. Performance of Gala on 18 dwarfing rootstocks: Ten-year summary of the 1994 NC-140 rootstock trial. Journal of the American Pomological Society 60:69-83
  • Parra-Quezada, R.A., T.L. Robinson, L.P. Parra-Bufanda, G. Fazio, T. Holleran and J. Osborne. 2006. Determinacion de la fuerza de la union del injerto en varios protainjertos de manzano. XXI Cogresso Nacional y Primero Internacional de fitogenetica. Abstr. 194.
  • Reighard, G.L., T. Beckman, R. Belding, B. Black, J. Cline, W. Cowgill, R. Godin, M. Kaps, T. Lindstrom, D. Ouellette, L. Stein, K. Taylor, C. Walsh, M. Whitting and T. Robinson. 2006. Performance of prunus rootstocks in the North American 2001 NC-140 peach trial. International scientific conference on fruit tree rootstocks for temperate zone: Biological, ecological and technological aspects, Abstracts p.75.
  • Robinson, T.L., G. Fazio, H.S. Aldwinckle, S.A. Hoying, and N. Russo. 2006. Field performance of Geneva apple rootstocks in the USA. Sodininkyste Ir Darzinninkyste. 25 (3):181-191.
  • Robinson, T.L., S.A. Hoying and R.L. Andersen. 2006. The integrated system of growing high quality sweet cherries in the east. Compact Fruit Tree 39(3):6-10.
  • Robinson, T.L., S.A. Hoying and R.L. Andersen. 2006. High-density peach training systems for NY fruit growers. Proc. of the 2006 Empire State Fruit and Veg. Expo. p. 32-35.
  • Robinson. T.L., S.A. Hoying and G.L. Reginato. 2006. The Tall Spindle apple planting system. NY Fruit Quarterly 14(2)21-28.
  • Robinson, T.L., S.A. Hoying, and R.L. Andersen. 2006. Performance of dwarfing cherry rootstocks in the Northeastern United States. Sodininkyste Ir Darzinninkyste. 25 (3):113-122.
  • Robinson, T., S. Hoying, and R. Andersen. 2006 What We have Learned About Growing High Density Sweet Cherries. http://www.glexpo.com/abstracts/2006abstracts/Cherry2006.pdf.
  • Russo, N.L., T. Robinson, G. Fazio and H. Aldwinckle. 2006. Rootstock blight in apple. NY Fruit Quarterly. 14(3):11-15.
  • Andersen, R.L., J. Freer and T.L. Robinson. 2006. Plum Rootstocks Trials At Geneva: A Progress Report. NY Fruit Quarterly 14(1)27-28.
  • Reighard, G.L., T. Beckman, R. Belding, B. Black, J. Cline, W. Cowgill, R. Godin, M. Kaps, T. Lindstrom, D. Ouellette, L. Stein, K. Taylor, C. Walsh, M. Whitting and T. Robinson. 2006. Performance of prunus rootstocks in the north american 2001 NC-140 peach trial. Sodininkyste Ir Darzinninkyste. 25 (3):327-333.
  • Robinson, T.L. 2006. The evolution towards more competitive apple orchard systems in the USA. 27th International Horticulture Congress Program p73.
  • Robinson, T.L. 2006. Interaction of fertilization, rootstock and irrigation on growth, thinning efficiency, yield and fruit quality of 'Empire' apple. Acta Hort. 721:41-48.
  • Robinson, T.L. 2006. Modern apple training systems. http://orchard.uvm.edu/uvmapple/hort/ROBINSON_ModernAppleTrainingSyst emsVTFGAFeb2006.PDF.
  • Robinson, T.L. 2006. Apple varieties, rootstocks and training systems. http://orchard.uvm.edu/uvmapple/hort/ROBINSON_AppleVarietiesAndRootst ocksVTFGAFeb2006.
  • Robinson, T.L. 2006. New apple rootstocks and training systems. http://www.utahhort.org/talks/2006/ROBINSON_Utah_Rootstocks_TrainingS ystems.pdf.
  • Robinson, T.L. 2006. The integrated system of growing high quality sweet cherries in the east. http://www.utahhort.org/talks/2006/ROBINSON_Utah_Integrated_SweetCher ry_Production.pdf.
  • Robinson. T.L. and S.A. Hoying. 2006. A More Competitive Apple Planting System http://www.glexpo.com/abstracts/2006abstracts/TreeFruit2006.pdf.
  • Robinson, T.L. Anderson, W. Autio, B. Barritt, J. Cline, R. Crassweller, W. Cowgill, C. Embree, D. Ferree, E. Garcia, G. Greene, C. Hampson, K. Kosola, M. Parker, R. Perry, T. Roper and M. Warmund. 2006. A multi-location comparison of Geneva 16, Geneva 41 and M.9 apple rootstocks across North America. Compact Fruit Tree 39(2):22-23.
  • Robinson, T.L., R.L. Andersen and S.A. Hoying. 2006. Performance of dwarfing cherry rootstocks in the Northeastern United States. International scientific conference on fruit tree rootstocks for temperate zone: Biological, ecological and technological aspects, Abstracts p.28.
  • Robinson, T.L., R.L. Andersen and S.A. Hoying. 2006. Performance of six high-density peach training systems in the northeastern United States. Acta Hort. 713:311-320.
  • Robinson, T.L., G. Fazio, H.S. Aldwinckle and S.A. Hoying. 2006. Field performance of Geneva apple rootstocks in the USA. International scientific conference on fruit tree rootstocks for temperate zone: Biological, ecological and technological aspects, Abstracts p.38.


Progress 01/01/05 to 12/31/05

Outputs
A national peach rootstock trial with Cresthaven as the scion variety was planted in 2002 as a part of the NC-140 regional research project. The Geneva, NY planting experienced severe winter cold damage in January 2004 and again in January 2005. We lost all of the flower buds each year. There has also been extensive wood damage and tree deaths from the cold. Although the trial is too young to give final conclusions some of the early clues on hardiness and dwarfing are very interesting. The most vigorous stock in this planting was Lovell followed by Adesto, Cadaman, MRS 2/5, Penta, Pumiselect, Controller 5 Krymsk 1 and Krymsk 2. The last three stocks were about 65-70 percent as large as Lovell. Following the two severe winters in 2004 and 2005, the trees with the greatest survival and the greatest percentage of functional canopy were Controller 5 and Kyrmsk 1 followed by Pumiselect, Lovell, Cadaman and Krymsk 2. The other three stocks (Adesto, MRS 2/5 and Penta) all had less than 40 percent survival. Although Lovell had relatively good survival, the canopy was largely non-functional. Although Pumiselect had good survival with a good canopy it had poor anchorage and is likely too weak to resist wind storms. It will need a trellis if planted commercially. A second peach rootstock trial in was planted in 2002 with RosePrincess nectarine as the scion. This trial compared Cadaman, Penta, Ishtara, Jaspi, Krymsk 1, and Mariana GF 8-1 rootstocks. Ishtara, Cadaman and Penta were the three most vigorous stocks, all three with significantly greater trunk cross-sectional area than Jaspi, Krymsk 1, and Mariana GF 8-1 in descending order of vigor. Almost half of the Mariana GF 8-1 trees died within four seasons and we suspect that this stock is probably incompatible with the RosePrincess scion. The behavior of the Ishtara stock in this trial was quite different from what we saw in an earlier trial with Redhaven Peach which was planted in 1994 where it was one of the least vigorous stocks among 19 other stocks. For the immediate future, Lovell and Bailey peach seedling rootstocks remain the recommended stocks for both peach and nectarine orchards in New York State.

Impacts
Lovell and Bailey peach seedling rootstocks remain the recommended stocks for both peach and nectarine orchards in New York State. New results from the 2005 season indicate that two new dwarfing stocks (Krymsk 1=VVA 1, Russian origin, and Controller 5=K146-43 from University of California) possess hardiness that surpasses that of Lovell and are more size controlling than either Bailey or Lovell. We have also found that some peach and nectarine cultivars are graft incompatible with some of the peach and plum rootstock rootstocks in our trials. Our results are preliminary and we need a couple of milder winters so that we can judge better their yield capacities.

Publications

  • Andersen, R.L., Robinson, T.L. and Freer J. 2005. Sweet cherry rootstock trials at Geneva. Proceedings of the Robert L. Andersen Stone Fruit Symposium. Cornell University, Geneva, NY pp 18.1-18.2.
  • Andersen, R.L., Robinson, T.L. and Freer J. 2005. Tart cherry rootstock trials at Geneva. Proceedings of the Robert L. Andersen Stone Fruit Symposium. Cornell University, Geneva, NY pp 18.3.
  • Andersen, R.L., Robinson, T.L. and Freer J. 2005. Peach rootstock trials at Geneva. Proceedings of the Robert L. Andersen Stone Fruit Symposium. Cornell University, Geneva, NY pp 18.4.
  • Andersen, R.L., Robinson, T.L. and Freer, J. 2005. Plum rootstock trials at Geneva. Proceedings of the Robert L. Andersen Stone Fruit Symposium. Cornell University, Geneva, NY pp 18.5.
  • Andersen, R.L., Robinson, T.L. and Freer J. 2005. Cherry Rootstocks Trials At Geneva. NY Fruit Quarterly 13(3):15-16
  • Andersen, R.L., Freer J. and Robinson T.L. 2005. Peach Rootstock Trials At Geneva: A Progress Report. NY Fruit Quarterly 13(4):29-30.
  • Autio, W.R., Robinson, T.L., Barritt, B.H., Cline, J.A., Crassweller, R.M., Embree, C.G., Ferree, D.C., Garcia, M.E., Greene, G.M., Hoover, E.E., Johnson, R.S., Kosola, K., Masabni, J., Parker, M.L., Perry, R.L., Reighard, G.L., Seeley, S.D., and Warmund, M. 2005. Performance of Fuji and McIntosh apple trees after 5 tears as affected by several semidwarf rootstocks in the 1999 NC-140 apple rootstock trial. Journal of the American Pomological Society 59:192-201.
  • Autio, W.R., Robinson, T.L., Barritt, B.H., Cline, J.A., Crassweller, R.M., Embree, C.G., Ferree, D.C., Garcia, M.E., Greene, G.M., Hoover, E.E., Johnson, R.S., Kosola, K., Masabni, J., Parker, M.L., Perry, R.L., Reighard, G.L., Seeley, S.D., and Warmund, M. 2005. Performance of Fuji and McIntosh apple trees after 5 years as affected by several dwarf rootstocks in the 1999 NC-140 apple rootstock trial. Journal of the American Pomological Society 59:202-214.
  • Fazio, G., Aldwinckle, H.S., Robinson, T.L., and Cummins J. 2005. Geneva 41: A new fire blight resistant, dwarf apple rootstock. HortScience 40: 1027 (Abstr.).
  • Fazio, G., Aldwinckle, H.S., Robinson, T.L., and Cummins J. 2005. Geneva 935: A new fire blight resistant, semi-dwarfing apple rootstock. HortScience 40: 1027 (Abstr.).
  • Fazio, G., Robinson, T., Aldwinckle, H., Mazzola, M., Leinfelder, M. and Parra, R. 2005. Traits of the next wave of Geneva apple rootstocks. Compact Fruit Tree 38(3):7-11.
  • Hrotko, K. and Robinson, T. 2005. Eighth international symposium on integrating canopy, rootstock, and environmental physiology in orchard systems. Chronica Hort. 45 (2):35-36.
  • Lang, G., Kappel, F., Andersen, R., Cline, J., Greene, G., Kosola, K., Perry, R., Robinson, T. and Seeley, S. 2005. Mid-trial report of the NC-140 regional sour cherry rootstock (1998) in North America. 5th International Cherry Symposium Abstracts p.90.
  • Robinson, T.L., Andersen, R.L. and Hoying S.A. 2005. Performance of Gisela rootstocks in six high-density sweet cherry training systems in Northeastern United States. 5th International Cherry Symposium Abstracts p.21.
  • Robinson, T., Fazio, G. and Aldwinckle, H. 2005 High-density orchards, dwarfing rootstocks more popular. The Fruit Grower News. 42 (2): 24-27.


Progress 01/01/04 to 12/31/04

Outputs
In 1998, two multi-site replicated rootstock trials were established by the US national rootstock testing group, NC-140. The trials compared 2 elite dwarf Geneva apple rootstocks which are tolerant to fire blight and Phytophthora root rot. The first trial used Jonagold as the scion and compared M.9 with Geneva G.16, and G.41. It was planted at 10 locations across North America. The second trial which was planted at 9 locations used Gala as the scion and compared only M.9 and G.16. At the end of 6 years, G.16 produced a tree slightly larger than M.9EMLA with Gala while with Jonagold tree size was similar to M.9EMLA. Productivity of G.16 was similar to M.9 in all trials. Trees of Jonagold on G.41 were slightly, but significantly smaller in size than M.9 EMLA, yet productivity was similar to M.9. Yield efficiency of G.41 was higher, but not significantly different than M.9EMLA. At the Geneva NY site there was no effect of tissue culturing of the stoolbed mother plants used to create the nursery liners of G.16. Tree size, yield, yield efficiency or root suckers were similar to non tissue culture stoolbeds indicating that with at least this stock, plants can be multiplied by tissue culture to establish stoolbeds without negative effects. Tree survival of G.16 and G.41 was better than M.9 where fire blight caused tree losses. Tree survival of G.16 was better than M.9, M.26 or B.9 following a mid winter cold event in January 2004 at a Northern NY site. G.16 is currently being commercialized in the US and Canada. G.41 will be patented and commercialized in Dec. 2004.

Impacts
High density apple orchards on dwarfing rootstocks have become common in many apple growing regions of the world. This has allowed apple growers to achieve earlier production, higher production and better fruit quality than previously. However, for many apple growers in North America, New Zealand and many locations in Europe, the bacterial disease fire blight is a serious threat to dwarf apple orchards. M.9 and M.26, the most common dwarfing apple rootstocks, are very susceptible to this disease and in some locations this disease limits the planting of dwarfing rootstocks. Outbreaks of the disease in the eastern US have decimated many dwarf apple orchards. There is a great need to develop new, highly productive apple rootstocks that are resistant to the biotic and climatic stresses common in North America. The rootstock breeding program a Cornell University has produced several fire blight resistant apple rootstocks. The current multi-site comparisons of CG rootstocks have shown that over a broad range of climates and soils, G.41 and G.16 are very similar in dwarfing to M.9 and both have good fire blight resistance and are quite productive. These stocks will help growers in fire blight areas of the world to plant high density orchards for improved profitability.

Publications

  • Autio W., J. Cline, R. Crassweller, C. Embree, E. Garcia, E, Hoover, K. Kosola, R. Perry, and T. Robinson. 2004. Early performance of Fuji and McIntosh apple trees on several dwarf rootstocks in the 1999 NC-140 rootstock trial.. HortScience 39: 799 (Abstr.).
  • Autio W., J. Cline, R. Crassweller, C. Embree, E. Garcia, E, Hoover, K. Kosola, R. Perry, and T. Robinson. 2004. Early performance of Fuji and McIntosh apple trees on several semidwarf rootstocks in the 1999 NC-140 rootstock trial.. HortScience 39: 800 (Abstr.).
  • Autio W., L. Andersen, B. Barritt, J. Cline, R. Crassweller, C. Embree, D. Ferree, E. Garcia, G. Greene, E, Hoover, S, Johnson, K. Kosola, J. Masabni, M. Parker, R. Perry, G. Reighard, T. Robinson. 2004. Early performance of Fuji and McIntosh apple trees on several dwarf rootstocks in the 1999 NC-140 rootstock trial. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.93 (Abstr.)
  • Autio W., L. Andersen, B. Barritt, J. Cline, R. Crassweller, C. Embree, D. Ferree, E. Garcia, G. Greene, E, Hoover, S, Johnson, K. Kosola, J. Masabni, M. Parker, R. Perry, G. Reighard, T. Robinson. 2004. Early performance of Fuji and McIntosh apple trees on several semidwarf rootstocks in the 1999 NC-140 rootstock trial. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.94 (Abstr.)
  • Leinfelder, M.M., I.A. Merwin, G. Fazio, and T. Robinson. 2004. Resistant rootstocks, preplant compost amendments, soil fumigation and row repositioning for managing apple replant disease. HortScience 39: 841 (Abstr.).
  • Robinson, T. L. (ed). 2004. Replanting for success. Syllabus for 2004 Cornell Indepth Fruit School. 120 pages. Supplied to Extension field staff and participating growers.
  • Robinson, T. 2004. Recent advances and future directions in orchard planting systems. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.72 (Abstr.)
  • Robinson, T. 2004. Effect of tree density and tree shape on light interception, tree growth, yield and economic performance of apples. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.79 (Abstr.)
  • Robinson, T.L. and S.A. Hoying. 2004. Which high-density orchard planting system for replant sites in NY is the most productive and profitable. Acta Hort. 636:701-709.
  • Robinson, T.L. and S.A. Hoying. 2004. Performance of elite Cornell Geneva apple rootstocks in long-term orchard trials on growers farms. Acta Hort. 658:221-229.
  • Robinson, T.L., R.L. Andersen, and S.A. Hoying. 2004. Performance of Gisela cherry rootstocks in the Northeastern United States. Acta Hort. 658:231-240.
  • Robinson, T.L., R.L. Andersen and S.A. Hoying. 2004. Performance of six high density cherry training systems in the northeastern United States. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.81 (Abstr.)
  • Robinson, T., L. Anderson, A. Azarenko, B. Barritt, G. Brown, J. Cline, R. Crassweller, P. Domoto, C. Embree, A. Fennell, D. Ferree, E. Garcia, A. Gaus, G. Greene, C. Hampson, P. Hirst, E. Hoover, S. Johnson, M. Kushad, R. Marini, R. Moran, C. Mullins, M. Parker, G. Reighard, R. Perry, J.P. Prive, C. Rom, T. Roper, J. Schupp, M.Warmund, W. Autio, W. Cowgil, K. Taylor, D. Wolfe. 2004. Performance Of Cornell-Geneva Rootstocks in Multi Location NC-140 Rootstock Trials Across North America. Acta Hort. 658:241-245.
  • Robinson, T.. L. Anderson, W. Autio, B. Barritt, J. Cline, R. Crassweller, W. Cowgill, C. Embree, D. Ferree, E. Garcia, G. Greene, C. Hampson, K. Kosola, M. Parker, R. Perry, T. Roper and M. Warmund 2004. A multi-location comparison of Geneva 16, Geneva 41 and M.9 apple rootstocks across North America. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.30 (Abstr.)
  • Robinson, T.L., A.M. DeMarree and S.A. Hoying. 2004. Economic comparison of five high density apple planting systems. 8th International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems. Program and Abstracts p.81 (Abstr.)
  • Robinson, T., G. Fazio, H. Aldwinckle and S. Hoying. 2004. Performance of the new Geneva apple rootstocks in trials in the US, NZ and Europe. Compact Fruit Tree 37(3): 91-94.
  • Robinson, T., G. Fazio, H. Aldwinckle, S. Hoying, K. Iungerman, and M. Fargione. 2004. Where do the Geneva apple rootstocks fit in New York state? NY Fruit Quarterly.12(4):3-6.


Progress 01/01/03 to 12/31/03

Outputs
From 1992 to 1999, five multi-site replicated rootstock trials were established by the US national rootstock testing group, NC-140. The trials compared elite Geneva apple rootstocks which were bred for tolerance to fire blight and Phytophthora root rot, high yield efficiency and good tree survival to commercial standards. The named Geneva rootstocks are designated as Geneva-TM or G stocks while unnamed numbered selections from Geneva are designated as CG stocks. In the 1992 plots which used 'Liberty' as the scion, Geneva-TM 11 and CG.3029 had the highest cumulative yield efficiency, good tree survival and also had good average fruit size. They had similar tree size as M.9, but exceeded the yield performance of M.9. In contrast, Geneva-TM 65 was more dwarfing than M.9 and had significantly lower cumulative yield efficiency and smaller fruit size than M.9. Among semi-dwarf stocks, Geneva-TM 30, CG.6210, CG.4222 and CG.5179 all exceeded the performance of M.7 and MM.106. In the 1993 plots which also used Liberty as the scion, CG.4247, CG.3041, CG.3902 and CG.3007 had the highest yield efficiencies and had good tree survival. All were similar in size to M.9, but performed significantly better than M.9 or M.26. Among the semi-dwarf stocks top performers were G.30, CG.6210, CG.222 and Geneva-TM 202. All performed significantly better than M.7. In the 1994 plots which used Gala as the scion, Geneva-TM 30 produced a tree similar in size to M.26 and more efficient than M.26 at 12 sites and less efficient at 6 sites. Fruit size was similar to M.26. G.30 generally had good survival; however, in 5 of 23 sites 50-60% of the trees broke off at the graft union during wind storms. In the 1998 and 1999 trials, Geneva-TM 16 has been slightly larger than M.9 with Gala, Fuji and McIntosh, but similar to M.9 with Jonagold. Productivity of Geneva-TM 16 has been similar to M.9 in all trials. CG.3041 has been similar in size and productivity to M.9 with Jonagold, Fuji and McIntosh.

Impacts
The multi-site rootstock trials we have conducted has helped identify strengths and weaknesses of the new series of Geneva rootstocks. It appears that all of the elite stocks have good fire blight resistance and are quite productive. However, each has deficiencies that must be understood before their adoption by the commercial apple industry. New fire blight resistant rootstock that are productive and precocious will help to strengthen the NY apple industry by giving growers viable options rootstock for new high density orchards.

Publications

  • Robinson, T.L., R.L. Andersen, and S.A. Hoying. 2003. Comportamiento de los patrones de cerezo Gisela en el noreste de Estados Unidos. ITEA 99:101-111.
  • Robinson, T.L., S.A. Hoying, M. Fargione, and K. Iungerman. 2003. On-farm trials of the Cornell-Geneva apple rootstocks in New York. Compact Fruit Tree 36(3):70-73.
  • Robinson, T. 2003. Effect of apple tree caliper and feathering on yield and orchard economics. HortScience 38:70 (Abstr.)
  • Robinson, T.L. and S.A. Hoying. 2003. Tree support systems: An investment that pays large dividends. Compact Fruit Tree 36:25-29.
  • Robinson, T.L. and S.A. Hoying. 2003. Descriptions of orchard planting systems. Compact Fruit Tree 36:50-64.
  • Robinson, T.L. and S.A. Hoying. 2003. Apple orchard planting systems. Proc. Successful Small-Scale Tree Fruit Production Workshop. p. 1-48, Ithaca NY.
  • Robinson, T.L, and S.A. Hoying. 2003. What tree density and training system should NY growers use with new apple orchards? New York Fruit Quarterly 11(1): 5-8.
  • Robinson, T.L. and S.A. Hoying. 2003. Tree support systems: An investment that pays large dividends. Nova Scotia Fruit Growers Assoc., 2002 Annual Rpt. p. 80-89.
  • Robinson, T.L., H.S. Aldwinckle, G. Fazio and T. Holleran. 2003. The Geneva series of apple rootstocks from Cornell: Performance, disease resistance, and commercialization. Acta Hort. 622:513-520.
  • Robinson, T, L. Anderson, A. Azarenko, B. Barritt, T. Baugher, G. Brown, G. Couvillon, W. Cowgill, R. Crassweller, P. Domoto, C. Embree, A. Fennell, E. Garcia, A. Gaus, R. Granger, G. Greene, P. Hirst, E. Hoover, S. Johnson, M. Kushad, R. Moran, C. Mullins, S. Myers, R. Perry, C. Rom, J. Schupp, K. Taylor, M. Warmund, J. Warner, and D. Wolfe. 2003. Performance of Cornell-Geneva apple rootstocks with Liberty as the scion in NC-140 trials across North America. Acta Hort. 622:521-530.
  • DeMarree, A., T.L. Robinson. and S.A. Hoying. 2003. Economics and the orchard system decision. Compact Fruit Tree 36:42-49.
  • Hoying, S.A. and T.L. Robinson. 2003. Tree quality: An important part of successful plantings. Compact Fruit Tree 36:21-24.
  • Lakso, A., D. Eissenstatt, and T. Robinson. 2003. Root growth patterns and mineral nutrient uptake. Proc. In-depth fruit school on apple mineral nutrition. p. 26. Cornell University, Ithaca, NY
  • Norelli, J.L., H.T. Holleran, W.C. Johnson, T.L. Robinson, and H.S. Aldwinckle. 2003. Resistance of Geneva and other apple rootstocks to Erwinia amylovora. Plant Disease. 8(1):26-32
  • Robinson, T.L. 2003. Rootstocks and production systems for success. 2002. Nova Scotia Fruit Growers Assoc., 2002 Annual Rpt. p. 31-45.
  • Robinson, T.L. 2003. Rootstock as a key component to high density orchards. Compact Fruit Tree 36:9-13.
  • Robinson, T.L. 2003. Tree density: The key factor in early production. Light interception: The key factor in high mature production. Compact Fruit Tree 36:14-20.
  • Robinson, T.L. 2003. Achieving a balance between vegetative growth and cropping. Compact Fruit Tree 36:33-36.
  • Robinson, T.L. 2003. A comparison of orchard systems with Empire, Jonagold, and Gala on eight rootstocks in New York. Compact Fruit Tree 36:37-40.


Progress 01/01/02 to 12/31/02

Outputs
In 1999 we established a replicated cherry systems trail at Geneva, NY with 3 cultivars (Hedelfingen, Lapins and Sweetheart), 3 rootstocks ( Gi.5, Gi.6 and MXM.2.) and 6 training systems (Zahn system-1196 trees/ha, Vogel system-897 trees/ha, Spanish Bush system-672 trees/ha), Central Leader system-336 trees/ha), Marchant system-1033 trees/ha, and the Perpendicular V system-996 trees/ha). After the first 4 years trees on Gisela 5 and Gisela 6 rootstocks have had 7 to 11 times greater production than trees on a standard rootstock MxM.2 when averaged over all 6 training systems. Fruit size from trees on Gisela 5 was smaller and had lower soluble solids than the other 2 stocks indicating that trees on this rootstock over-cropped in 2002. On a hectare basis the Zahn system had the highest yield (6.2 tons/ha) followed by the Vogel system (3.4 tons/ha), the Marchant system (2.3 tons/ha), the Perpendicular V system (2.3 tons/ha), the Spanish Bush system (1.2 tons/ha), and the Central Leader system (0.5 tons/ha). Results with Lapins and Sweetheart were similar. The combination of Zahn training and Gi.5 rootstock resulted in very high yields per hectare of 10.2, 6.9 and 7.2 tons/ha for Hedelfingen, Lapins and Sweetheart respectively. Yields among systems largely reflected planting density. The Zahn system had the highest tree density and the highest yield per hectare while the traditional Central Leader system had the lowest yield and the lowest tree density. The Zahn system had the smallest fruit size and the lowest fruit soluble solids indicating that trees trained to Zahn over-cropped in 2002. The Vogel system had the second highest yield but had the best fruit size and soluble solids indicating that it was not over-cropped. Although results are preliminary, it appears that high density planting systems combined with new precocious rootstocks can give much higher yields of excellent quality fruit in the first 4 years than the traditional Central Leader system. A sweet cherry rootstock trial planted in 1998 has shown three groups of rootstocks with respect to sweet cherry scion vigor. The two seedling stocks (Mazzard and Mahaleb) continue as most vigorous with Gisela 6, Weiroot 10, and Weiroot 13 not statistically different from the seedling stocks. There appears to be a trend that the 3 later stocks will end up statistically smaller than the seedling stocks after a few more years. The mid-vigor group included Weiroot 158, Gisela 195-20, and Edabriz. The low vigor group included Gisela 7, Weiroot 72, Gisela 5, Weiroot 53, and Gisela 209/1. In general, less vigorous stocks were more yield efficient, except that Gisela 209/1 had low fruit set and had the lowest vigor status. Relative propensity to sucker (most to none) was: Gisela 7, Weiroot 13, Weiroot 10, Weiroot 72, Weiroot 158, Weiroot 53, Mazzard, Edabriz, Gisela 195/20, Mahaleb, Gisela 209/1, Gisela 6, Gisela 5.

Impacts
Our trials with sweet cherries dwarfing rootstocks are providing guidance to NY growers on how to profitably grow sweet cherries. Our results show the value of the precocious Gisela rootstocks and high planting densities for early production. Among the pruning systems the Zahn system had the least pruning in the first 2 years and has had the highest yield per tree. High density orchard systems that combine new precocious rootstocks, high tree densities, raised-beds to circumvent low oxygen/wet-feet problems and minimal pruning can give yields up to 10 Mt/ha in the fourth year. With a high value crop like sweet cherries this should help rapidly recoup the investment associated with planting a new cherry orchard. Although our early results are very encouraging the long term performance of high density sweet cherry systems in the North East of the United States is not proven. This work will help to strengthen the NY cherry industry by giving growers viable options for diversification.

Publications

  • Agnello, A.M., A.J. Landers, W.W. Turechek, D.A. Rosenberger, T.L. Robinson, J.R. Schupp, L. Cheng, P.D. Curtis, D.I. Breth, and Hoying, S.A. 2002. Pest management guidelines for commercial tree-fruit production 2002. Cornell University, Ithaca NY
  • Kuo-Tan L., A. Lakso, and T. Robinson. 2002. Summer pruning: The good the bad and the ugly. New York Fruit Quarterly 10(4):29-31.
  • Lang, G, R. Andersen and T. Robinson. 2002. Gaining on Gisela cherries. Fruit Grower 121(1):17-18.
  • Marini, R.P., J.A. Barden, J.A. Cline, R.L. Perry, and T. Robinson. 2002. Effect of apple rootstocks on average Gala fruit weight at four locations after adjusting for crop load. J. Amer. Soc. Hort. Sci. 127:749-753.
  • Norelli J.L., H.S. Aldwinckle, H.T. Holleran, T. L. Robinson and W.C. Johnson. 2002. Resistance of Geneva apple rootstocks to Erwinia amylovora when grown as vegetative shoots and orchard trees. Acta Hort.
  • Robinson, T. 2002. The New York state apple research and development program: Ten years of successful research support for the apple industry. New York Fruit Quarterly 10(2): 3-17.
  • Robinson, T and S. Hoying. 2002. The New York Fruit Quarterly magazine's 10th anniversary. New York Fruit Quarterly 10(3): 1
  • Robinson, TL. and S.A. Hoying. 2002. On-farm trials of the Cornell Geneva apple rootstocks in NY. New York Fruit Quarterly 10(4):22-26.
  • Robinson, T. and S. Hoying. 2002. What we have learned from our latest orchard planting systems trial in New York State. Compact Fruit Tree 35(4):103-106.
  • Robinson, T., H.S. Aldwinckle, and J.L. Norelli. 2002. Effect of Mineral Nutrition on Blossom, Shoot and Rootstock Fire Blight of Young, Dwarf Apple Trees. Proc. 9th International Workshop on Fire Blight. Havelock North, New Zealand. (In press)
  • Robinson, T., L. Anderson, A. Azarenko, B. Barritt, G. Brown, J. Cline, R. Crassweller, P. Domoto, C. Embree, A. Fennell, D. Ferree, E. Garcia, A. Gaus, G. Greene, C. Hampson, P. Hirst, E. Hoover, S. Johnson, M. Kushad, R. Marini, R. Moran, C. Mullins, M. Parker, R. Perry, J.P. Prive, G. Reighard, C. Rom, T. Roper, J. Schupp, M.Warmund. 2002. Performance Of Cornell-Geneva Rootstocks in the Multi Location NC-140 Rootstock Trials Across North America. Compact Fruit Tree 35(4):99-102.
  • Schupp, J.R., D.A. Rosenberger, T.L. Robinson, H. Aldwinckle, J. Norelli, and P.J. Porpiglia. 2002. Post-symptom sprays of Prohexadione-calcium affect fire blight infection of Gala apple on susceptible and resistant rootstocks. HortScience 37:903-905.


Progress 01/01/01 to 12/31/01

Outputs
Two large field trials of 4 orchard systems were planted on growers farms in 1994 and 1995 (Central Leader/M.7, Vertical Axis/M.7, Vertical Axis/M.26 and Vertical Axis/M.9). In the first two years there was no fruit production with any system. Beginning in the third year there was a small crop with systems that utilized either M.26 or M.9 rootstock but not with systems that utilized M.7 rootstock. In years 5-8 trees approached full production with some varieties in the highest density systems reaching 50 tons/ha. Cumulative yields over the development years were largely a function of tree density with systems on dwarfing rootstocks (M.9 and M.26) giving the highest yields. The traditional system of Central leader/M.7 rootstock achieved less than 1/3 of the high density system. There was considerable variation among the productivity of varieties. In the older plot the most productive variety was Jonagold but it suffered from extreme biennial bearing with low crops in 1998 and in 2000. Rome and Idared were much more annual but slightly lower yielding. Averaged over all varieties the highest density system produced almost 3 times that of the traditional central leader system over the first 7 years. At the younger block, Mutsu, NY674 and Fortune were the most productive varieties when grown in the Vertical Axis/M.9 system. Liberty, Fuji and Jonagold were intermediate and Northern Spy was very unproductive. Averaged over all varieties the highest density system produced almost 4 times that produced by the traditional low density system over the first 6 years. In 1999 we established a replicated cherry systems trail at Geneva, NY with 3 cultivars (Hedelfingen, Lapins and Sweetheart) and 3 rootstocks ( Gi.unknown, Gi.6 and MXM.2.) In 2001 (the first crop), yields of the Gi.unknown rootstock were highest (1.01 kg/tree) with Gi.6 yields intermediate (0.83 kg/tree) and MXM2 with the lowest yield (0.02 kg/tree). Among systems, the Zahn system (1196 trees/ha) had the highest yield per tree (1.08 kg/tree) followed by the Vogel (897 trees/ha - 0.76 kg/tree), Spanish Bush (672 trees/ha - 0.57 kg/tree), Central Leader (336 trees/ha - 0.50 kg/tree), Marchant ( 1033 trees/ha - 0.44 kg/tree) and the Perpendicular V system (996 trees/ha) with the lowest yield per tree (0.28 kg/tree). On an acre basis the Zahn system had the highest yield (0.58 tons/acre) followed by the Vogel system (0.31 tons/acre), the Marchant system (0.20 tons/acre), the Spanish Bush system (0.17 tons/acre), the Perpendicular V system (0.12 tons/acre and the Central Leader system (0.08 tons/acre). The yields largely reflected density; however, the Zahn system because of its high yield per tree and the highest tree density produced almost double the yield per acre of any other systems. Fruit size was largest on Gi.6 (7.0g), intermediate on Gi.unknown (6.8g) and smallest on MXM2 (6.4g). Fruit soluble solids was highest with the Zahn, Central Leader, and the Perpendicular V systems ((17.5%), intermediate with the Vogel and Marchant systems (16.5%) and lowest with the Spanish Bush system (16.1%). This likely reflects excessive shade within the Spanish Bush canopy.

Impacts
Our results with orchard systems show that the highest tree densities are much more productive than the traditional lower densities. It appears that low density systems are not profitable any more while the high density systems are still profitable. The productivity of varieties varies considerably and the profitability of high density systems depends on high yielding varieties. Our trials with sweet cherries dwarfing stocks Gisela Series rootstocks is providing guidance to NY growers on how to profitably grow sweet cherries. Our results so far show the value of the precocious Gisela rootstocks and the value of high tree densities for early yields. Among the pruning systems the Zahn system had the least pruning in the first 2 years and has had the highest yield per tree. This coupled with our work on the use of raised-bed-culture in stone fruit orchards to circumvent low oxygen/wet-feet problems will help to strengthen NY cherry industry by giving growers viable options for diversification.

Publications

  • Hirst, P.M., C.R. Rom, C.R. Hampson, A. Gaus, S.C. Myers, J. Garner, P.A. Domoto, M.M. Kushad, G.R. Brown, J.R. Schupp, W.A. Autio, R.L. Perry, J.P. Prive, W.P. Cowgill Jr., M.L. Parker, R. Unrath, T.L. Robinson, E. Stover, D.C. Ferree, J.A. Cline, E. Mielke, R. M. Crassweller, G.M. Greene, G.L. Reighard, C.A. Mullins, J.L. Anderson, J.A.Barden, R.P. Marini, B.H. Barritt, T. Roper. 2001. Early performance of Gala on 18 dwarf and 4 semi-dwarf rootstocks growing at 24 sites in North America. Acta Hort. 557:199-205.
  • Johnson W.C., H.S. Aldwinckle, J.N. Cummins, P.L. Forsline, H.T. Holleran, J.J. Norelli, and T.L. Robinson. 2001. The USDA-ARS/Cornell University apple rootstock breeding and evaluation program. Acta Hort. 557:35-40.
  • Johnson W.C., J.N. Cummins, H.T. Holleran, S.A. Hoying and T.L. Robinson. 2001. Orchard trial performance of elite Geneva series rootstocks. Acta Hort. 557:63-68.
  • Marini, R.P., B.H. Barritt, J.A. Barden, J. Cline, E.E. Hoover, R.L. Granger, M.M..Kushad, M. Parker, R.L. Perry, T. Robinson, S. Khanizadek, and C.R. Unrath. 2001. Performance of ten apple orchard systems: Ten-year summary of the 1990 NC-140 systems trail. Journal of the American Pomological Society 55(4): 222-204.
  • Marini, R.P., B.H. Barritt, J.A. Barden, J. Cline, R.L. Granger, M.M..Kushad, M. Parker, R.L. Perry, T. Robinson, S. Khanizadek, and C.R. Unrath. 2001. Performance of Gala apple on eight dwarf rootstocks: Ten-year summary of the 1990 NC-140 rootstock trail. Journal of the American Pomological Society 55(4): 197-204.
  • Robinson, T.L. 2001. Principios de manejo de huertos de alta densidad. IV Enfrute: Encontro National Sobre Fruticultura de Clima Temperado p183-196.
  • Robinson, T.L. 2001. Principios de manejo, de poda y portainjertos de huertos de alta densidad. VII Simposium Internacional Sobre el Manzano y Frutales de Clima Templado, Cuauthemoc, Chih., CD-Rom Proceedings.
  • Robinson, T. and S. Hoying. 2001. Processing apple planting systems trials. New York Fruit Quarterly 9(4): 17-19.
  • Robinson, T., H.S. Aldwinckle, and J.L. Norelli. 2001. Effect of Mineral Nutrition on Blossom, Shoot and Rootstock Fire Blight of Young, Dwarf Apple Trees. 9th International Workshop on Fire Blight, Abstracts (Abstr.)
  • Robinson, T., H.S. Aldwinckle, and J.L. Norelli. 2001. Effect of Mineral Nutrition on Blossom, Shoot and Rootstock Fire Blight of Young, Dwarf Apple Trees. Proc. 9th International Workshop on Fire Blight. Havelock North, New Zealand. In press.
  • Turechek, B., D. Rosenberger, H. Aldwinckle, J. Schupp, and T. Robinson. 2001. Using Apogee to help manage fire blight. Scaffolds 8:1-4.


Progress 01/01/00 to 12/31/00

Outputs
In a 1994 Gala apple plot the greatest cumulative yield efficiency was with P.16 followed by M.9T337, M.9Emla, Mark, B.491 M.9Pajam2 and P.22. All of the other M.9 clones had lower efficiency as well as B.9 and O.3. There were significant differences in tree size among M.9 clones. The smallest clone was M.9Flueren56 followed by M.9T337. The M.9EMLA clone was intermediate while the Pajam1, Pajam2 and Nic29 clones were the most vigorous. The three most vigorous clones were similar in size to M.26. The V.3 rootstock gave a tree size similar to M.9T337 and B.9 and had similar yield efficiency. In the semi-dwarf plot G.30 had the highest yield efficiency followed by V.2. A group of younger trials planted in 1998 at Geneva, in the Hudson Valley and in the Champlain Valley showed that Gala trees on G.16 have grown significantly larger than trees on M.9. However with Jonagold there was no significant differences in tree size between the G.16 and M.9 trees. With the Jonagold trees CG.3041 was included and was similar in tree size to the G.16 and M.9 trees. G.16 had the highest yield efficiency with Jonagold but had intermediate yield efficiency with Gala. Greenhouse inoculations of a collection of apple stocks from around the world with 4 strains of fire blight showed that the CG stocks are largely resistant while the JTE stocks are highly susceptible. The JM and Vineland stocks are intermediate. A field planting of third year Gala on CG rootstocks which was inoculated with fire blight in 1999 was evaluated for tree survival in 2000. Most of the CG rootstocks had high survival rates while most M.9 and M.26 trees were killed. G.11 gave intermediate survival. In a 1998 sweet cherry rootstock trial there appear to be three size categories of rootstocks: High vigor (Mazzard, Mahaleb, Gi 6, and Weiroot10), Mid-vigor (Weiroot13, Weiroot158, Gi 195-20, Edabriz, and Gi 473/10) and Low Vigor (Gi 7, Weiroot72, Gi 5, Weiroot53, and Gi 209/1). The correlation between vigor and earlier defoliation was significant (r=-0.55). The more vigorous stocks were later in defoliation. Correlations between rootstock vigor and bacterial cankers (as visually diagnosed as gummy eruptions from injury points in the bark of primary and secondary scaffolds) had a correlation coefficient of 0.32. But the correlation between vigor and cankers on the central leaders was much weaker, (r=0.13). A sweet cherry branching experiment showed that spraying with Promalin mixed in white paint or notching above every third bud at bud swell were relatively ineffective methods of stimulating branching in the lower or middle third of 1 year cherry shoots. However bud removal which consisted of removing 2/3 of the buds along the shoot (every third bud was left and the others were rubbed out at bud swell) was very effective and gave a relatively uniform distribution of lateral branches along the shoot.

Impacts
The NC-140 plantings are regularly used as demonstration plots of new and future introductions from Geneva rootstock series to visiting scientists, nurserymen, graduate students, and interested growers. The cooperative testing of the new rootstocks through the national NC-140 group will speed the selection process of superior stocks with widespread adaptability. This will aid in the profitability of apple growing and allow successful growing of dwarf trees in fire blight prone areas of the US. Our comparisons of M.9 clones is helping to provide growers with guidance about which clones of M.9 to plant in NY. Our trials with sweet cherries dwarfing stocks Gisela Series rootstocks is providing guidance to NY growers on how to profitably grow sweet cherries.. This coupled with our work on the use of raised-bed-culture in stone fruit orchards to circumvent low oxygen/wet-feet problems will help to strengthen NY cherry industry by giving growers viable options for diversification

Publications

  • Aldwinckle, H., J. Norelli, S. Brown, T. Robinson, E Borejsza-Wysocka, H. Gustafson, J.P. Reynoird, and M.V.B. Reddy. 2000. Genetic engineering of apple for resistance to fire blight. New York Fruit Quarterly 8(1)):24-26.
  • Hoying, S.A, and T.L. Robinson. 2000. The orchard planting systems puzzle. Acta Hort. 513:257-260.
  • Hoying, S.A., T.L. Robinson and A.DeMarree. 2000. Production, fruit quality and labor requirements of five high-density apple orchard systems over 10 years. 7th International Symposium on Orchard and Plantation Systems. Program and Abstracts p. 35.
  • Johnson W.C., H.S. Aldwinckle, J.N. Cummins, P.L. Forsline, H.T. Holleran, J.J. Norelli, and T.L. Robinson. 2000. The USDA-ARS/Cornell University apple rootstock breeding and evaluation program. 7th International Symposium on Orchard and Plantation Systems. Program and Abstracts p. 3.
  • Johnson W.C., J.N. Cummins, H.T. Holleran, S.A. Hoying and T.L. Robinson. 2000. Orchard trial performance of elite Geneva series rootstocks. 7th International Symposium on Orchard and Plantation Systems. Program and Abstracts p. 7.
  • Marini, R.P., T. Robinson, et al. 2000. Performance of `Gala' apple on Four Semi-dwarf rootstocks; A five year summary of the 1994 NC-140 Semi-dwarf rootstock trial. Journal of the American Pomological Society 54(2): 84-91.
  • Marini, R.P., T. Robinson, et al. 2000. Performance of `Gala' apple on Four Semi-dwarf rootstocks; A five year summary of the 1994 NC-140 Semi-dwarf rootstock trial. Journal of the American Pomological Society 54(2): 92-107.
  • Robinson T.L. 2000. Long-term performance and economics of high-density apple orchard systems. 7th International Symposium on Orchard and Plantation Systems. Program and Abstracts p. 33.
  • Robinson, T.L. 2000. V-shaped apple planting systems. Acta Hort. 513:337-347.
  • Robinson. T.L. 2000. Pruning, training and planting density to make money. Proc. New England Fruit Meetings 106: in press
  • Robinson T.L. and J.A. Flore. 2000. The physiological basis of orchard systems. 7th International Symposium on Orchard and Plantation Systems. Program and Abstracts p.61.
  • Robinson, T. L and S. A. Hoying. 2000. Lessons learned about tree support from the 1998 labor-day storm. Compact Fruit Tree 33:12-18.


Progress 01/01/99 to 12/31/99

Outputs
A trial of commercially available dwarf stocks was concluded after 10 years. The highest cumulative yield was with O.3 followed by M.9, B.9, M.26, and Mac.39 respectively. The highest cumulative yield efficiencies were with M.27, Mark, M.9, and Mac.39. B.9 had significantly lower cumulative yield efficiency than M.9. M.26 and P.1 showed the lowest yield efficiency. Two trials with the new Cornell-Geneva (CG) apple rootstocks has shown the best dwarf stocks are CG.26, CG.4247, CG.3041, CG.3902, CG.4003, CG.38 CG.5046 CG.6737, CG.3029, and G.11. They all exceeded the performance of M.9. . Among this group CG.3041 has been tested on several grower's farms where it has been a top performer in the dwarf class. Another Geneva dwarfing stock, G.65, had significantly lower cumulative yield efficiency and smaller fruit size than M.9. Among semi-dwarf stocks, G.30, CG.6210, CG.2a CG.67, CG.222, CG.6143, CG.517, CG.6874, CG.5012, and CG.7760 were top performers. They exceeded the performance of M.7. Among vigorous stocks CG.756, CG.6239, CG.6253, CG.5156, CG.6723, and CG.8189 were top performers. These stocks exceeded the performance of MM.111. In another trial of dwarfing stocks the greatest cumulative yield efficiency was with B.491 followed by Mark, P.16, P.22 and M.9 (6 clones). There were significant differences in tree size among M.9 clones. The smallest clone was M.9Flueren56 followed by M.9T337. The M.9EMLA clone was intermediate while the Pajam1, Pajam2 and RN29 clones were the most vigorous. The three most vigorous clones were similar in size to M.26. B.9 and O.3 had intermediate efficiency while V.1 and P.2 had the lowest yield efficiency. In the semi-dwarf plot G.30 had the highest yield efficiency followed by V.2. M.26 was third while P.1 was lowest. G.30 was the smallest tree and was significantly smaller than V.2. Based on our rootstock work we continue to recommend M.9, B.9, O.3 and M.26 as the preferred rootstocks for NY. Since O.3 is more vigorous than M.9, it should be especially useful in low vigor sites and in cooler climates Trees on G.16 are recommended only for trial since long-term trials are not yet complete and its ultimate tree size is unclear at this time. It may be closer to M.26 in size than M.9. Within M.9 clones the more vigorous clones (Pajam 2 or RN29) which are very similar to M.26 in size should be used in weaker soils or with weak scions while the weaker M.9 clones should be used in virgin ground or with vigorous scions. Both M.9EMLA and M.9T337 are intermediate in size and similar in performance. B.9 and O.3 are specifically recommended over M.9 for the cold climate areas of New York. Among semidwarf stocks, G.30 which is M.7 size continues to perform much better than M.7 and in some cases better than M.26. Its problems are that it is difficult to produce in the stool bed due to spines and the graft union is more brittle than M.7 especially with Gala. Thus G.30 will have to be supported with a post and wire system in all orchards. Despite its problems, G.30's yield performance is spectacular and is recommended for planting in NY.

Impacts
Based on our rootstock work we recommend M.9, B.9, O.3 and M.26 as the preferred rootstocks for NY. B.9 and O.3 are specifically recommended over M.9 for the cold climate areas of New York. Trees on G.16 are recommended only for trial since long-term trials are not yet complete. Among M.9 clones, the more vigorous clones (Pajam 2 or RN29) should be used in weaker soils or with weak scions. Among semidwarf stocks, G.30 continues to perform much better than M.7 and is recommended for planting in NY. It should be supported with a post and wire system in all orchards.

Publications

  • Andersen, R.L, T.L. Robinson and G.A. Lang. 1999. Managing the Gisela cherry rootstocks. New York Fruit Quarterly 7(4):19-22.
  • Hoying S.A. and T.L. Robinson. 1999. The super spindle in New York. New York Fruit Quarterly 7(1):23-26.
  • Johnson W.C., H.S. Aldwinckle, P.L. Forsline, H.T. Holleran, J.J. Norelli, and T.L. Robinson. 1999. The USDA-ARS/Cornell University apple rootstock breeding and evaluation program. HortScience 34:450 (Abstr.)
  • Johnson W.C., K.J. Niklas, T.L. Robinson, H.T. Holleran, S.A. Hoying, M. Goffinet and M.J. Welser. 1999. Graft union strength in apple trees. HortScience 34:450 (Abstr.)
  • Robinson, T. L and S. A. Hoying. 1999. What we learned about tree support from the 1998 Labor-Day storm. New York Fruit Quarterly 7(2):17-24.
  • Robinson, T.L., and W.C. Johnson. 1999. Apple rootstocks for the next century. HortScience 34: (Abstr.)


Progress 01/01/98 to 12/31/98

Outputs
A 1990 rootstock trial using Gala as the scion showed that cumulative yield was highest with O.3 followed by M.9EMLA, B.9, M.26 and Mark, respectively. P.1 and M.27 had the lowest yield. The highest cumulative yield efficiencies were with M.9, M.27, Mark and Mac.39. B.9 had significantly lower yield efficiency than M.9. M.26 and P.1 showed the lowest yield efficiency. A 1992 trial of CG rootstocks showed that among dwarf stocks CG.29, CG.737 and G.11 had the highest cumulative yield efficiency and also had good average fruit size. All three exceeded the performance of M.9. G.65 had significantly lower cumulative yield efficiency than CG.11 and also had significantly smaller fruit size. Among semi-dwarf stocks, CG.30, CG.210, CG.2a CG.67, CG.222, CG.143, CG.517 were top performers. They exceeded the performance of M.7. Among vigorous stocks CG.189 and CG.239 were top performers. These stocks exceeded the performance of MM.111. A 1993 trial of CG rootstocks showed that among dwarf stocks CG.26, CG.247, CG.902, CG.41, CG.3, CG.38 and CG.46 had the highest yield efficiencies. All performed significantly better than M.9. Among this group CG.41 has been tested on several grower's farms where it has been a top performer in the dwarf class. Among the semi-dwarf stocks top performers were CG.30, CG.874, CG.75-11 and CG.210. All performed significantly better than M.7. Among vigorous stocks CG.239, CG.253, CG.156, CG.723, and CG.189 and were top performers. These stocks exceeded the performance of MM.111. Trees of G.30, M.7 and M.26 with Gala, Liberty and Empire were dug-up and subjected to graft union breakage tests. The G.30 union was found to be weaker than either of the other two stocks. This will require this semi-dwarfing stock to be trellised. The Gala/G.30 union was much weaker than the Gala/M.26 union. All Gala unions were weaker than Liberty or Empire unions.

Impacts
(N/A)

Publications

  • Stover, E.W., Walsh, C.S. 1998. Shank tissue proliferations in apple rootstocks: effects on tree growth, and correlation with site factors.Fruit Var. J. 52:28-31.
  • Stover, E., Walsh, C. 1998. Crown gall in apple rootstocks: inoculation above and below soil and relationship to root mass proliferation. HortScience 38:92-95.
  • Rashid, A. Y. 1998. Effect of irrigation on young apple tree growth and yield. M.S Thesis, Cornell Univ. Ithaca NY.
  • Robinson, T.L. 1998. Effect of canopy angle and row spacing on tree growth, yield, light interception, and fruit quality of Y-trellis trained apple trees. HortScience 33:547. (Abstr.)
  • Robinson, T.L. 1998. The apple orchard planting systems puzzle. XXVth International Hort. Congress Abstracts. p.134. (Abstr.)
  • Robinson, T.L. 1998. V-shaped apple planting systems. XXVth International Hort. Congress Abstracts. p.137. (Abstr.)


Progress 01/01/97 to 12/31/97

Outputs
The 1987 cherry rootstock trial has shown that Gisela 10 (Gi 173-9), Gisela 6 (Gi 148-1), Gi 172-7 and Gi 154-7 had better yield efficiency than 9 others. Heavy dormant pruning resulted in larger fruit size but lower yields. Irrigation did not increase fruit size. The 1988 pear rootstock trial has shown that fruit size and production efficiency were greatest for OHF.40 and the large tree type of Pyrus calleryana followed by OHF.217 and P.betulifolia. The 1990 apple rootstock trial has shown that the highest cumulative yield was with M.9, B.9 and O.3 while the higher cumulative yield efficiency was with M.27, Mark, Mac.39, and M.9. Only M.26 and P.1 showed lower yield efficiency than the other stocks. The 1992 apple rootstock trial has shown that CG.29, CG.50, G.11 had the highest cumulative yield efficiency. G.65 had significantly lower yield efficiency than CG.11. Among the more vigorous stocks the highest yield efficiencies were with CG.737, CG.30, and CG.2. The 1993 apple rootstock trial has shown that CG.26, CG.902, CG.247, CG.41, CG.3, and CG.38 were the top performers. Among the more vigorous stocks, top performers were CG.30, CG.874, and CG.75-11. In the 1994 apple rootstock trial comparing clones of M.9, three clones (Nic29, Pajam2 and Pajam1) were more vigorous than the EMLA clone while two clones (NAKBT337 and Flueren56) were less vigorous than M.9EMLA. All appear to have similar productivity and yield efficiency. In the 1994 semi-dwarf plot G.30 had the highest yield efficiency followed closely by V.2. M.26 was intermediate while P.1 was lowest.

Impacts
(N/A)

Publications

  • Barritt, B.H. J.A. Barden, J. Cline, R.C. Granger, M.M. Kushad, R.P. Marini, M. Parker, R.L. Perry, T.L. Robinson, C.R. Unrath, and M. A. Dilley. 1997. Performance of Gala at year 5 with eight apple rootstocks at an 8 location North American NC-140 trial. Acta Hort. 451:129-135.
  • Robinson, T.L. 1997. Interaction of tree from and rootstock on light interception, yield, and yield efficiency of Empire and Jonagold trained to 4 systems. Acta Hort. 415:427-436.
  • Robinson, T.L. 1997. Effect of spacing and rectangularity on tree growth, yield, light interception, and fruit quality of Y-trellis trained apple trees. HortScience 32:506 (Abstr.)
  • Robinson, T.L., S.A. Hoying, and W.H. Smith. 1997. Training strategies for high density orchards of the future. Proc. New England Fruit Meetings. 103:27-36.
  • Robinson, T.L., J.N. Cummins, S.A. Hoying and W.H. Smith. 1997. Comercial orchard evaluation of the new Cornell-Geneva rootstocks. Acta Hort. 451:113-119
  • Barritt, B. H., J. A. Barden, J. Cline, R.C. Granger, M.M. Kushad, R.P. Marini, M. Parker, R.L. Perry, T.L. Robinson, C.R. Unrath and M.A. Dilley. 1997. North American NC-140 apple orchard systems trial. Acta Hort. 451:443-452.
  • Hoying, S.A. and Robinson, T.L. 1997. Planting systems trials in western New York. Compact Fruit Tree 30:41-45.
  • Hoying, S. A. and T. L. Robinson. 1997. The perfect apple planting system?. American Agriculturist. 1997.
  • Lakso, A.N. and T.L. Robinson. 1997. Principles of orchard systems management-Optimizing supply, demand and partitioning in tree fruits. Acta Hort 451:405-415.
  • Robinson, T.L., J.N. Cummins, S.A. Hoying, and W.H. Smith. 1997. The new Geneva apple roostsocks. Compact Fruit Tree 30:1-5
  • Tustin, S., D. Ferree, S. Myers, L. Corelli-Grappadelli, A. Lakso, T. Robinson, J. Flore, R. Perry, S. Breitdreutz, B. Barritt, B. Konishi, C. Rom, A. Webster, C. Atkinson, J. Palmer and W. Cashmore. 1997. The international apple growth study. Acta Hort. 451:693-699.


Progress 01/01/96 to 12/30/96

Outputs
Results with the new Cornell-Geneva apple rootstocks established on growers farms are: 1) Geneva 65 (G.65) is significantly smaller than M.9. Without irrigation Empire and Liberty trees on G.65 have been too weak with insufficient leaf area for optimum fruit size and have generally had lower efficiency than M.9. 2) G.16 is similar in size and productivity to M.9 but is resistant to Phytophthora, and fire blight. It is vigorous in the stoolbed and nursery row yet is size controlling in the orchard. It is suckerless, has superior anchorage to M.9 and is not as brittle. In Geneva it has grown without support, but support is recommended for commercial plantings. It slightly susceptible to woolly apple aphids and powdery mildew. It has had little testing outside of Geneva but is being released this winter. 3) Geneva 11 (G.11) is similar in size to M.26 and has performed as well as M.26 or M.9 through year 4 with Liberty as the scion. 4) Geneva 30 (G.30) is similar in vigor to M.7 but much more productive. After 6 years, trees on G.30 have had double the yield of trees on M.7 with yield efficiency as good as M.26. G.30 trees produced moderate suckering. 5) Four Cornell-Geneva rootstocks are under consideration for release as woolly apple aphid resistant stocks. CG.179, 202, 210 and 935. CG.179 and 202 are smaller than M.7 but larger than M.26. CG.935 is slightly larger than M.26 but has very high yield efficiency. CG.210 is similar in size to M.7 but with better efficiency.

Impacts
(N/A)

Publications

  • Barritt, B.H., T.L. Robinson, and et al. 1997. Performance of Gala through year 5 with eight apple rootstocks in an 8-location NC-140 trial. Acta Hort. (in press)
  • Barritt, B.H., J.A. Barden, J. Cline, R.C. Granger, M.M. Kushad, R.P. Marini, M.Parker, R.L. Perry, T.L. Robinson, C.R. Unrath and M.A. Dilley. 1997. Performance through year 5 of the NC-140 orchard systems trial. Acta Hort. (in press)
  • Robinson, T.L. 1997. Interaction of tree from and rootstock on light interception, yield, and yield efficiency of 'Delicious' and 'Jonagold' trained to 4 systems. Acta Hort. (in press)
  • Robinson, T.L., J.N. Cummins, S.A. Hoying and W.H. Smith. 1996. The new Geneva dwarfing apple rootstocks. Proc. Utah State Hort. Soc. (in press).
  • Robinson, T.L., J. Cummins, S. Hoying and W. Smith. 1996. Performance of the Cornell-Geneva apple rootstocks in New York. Compact Fruit Tree 29:7-11.
  • Robinson, T.L., J.N. Cummins, and S.A. Hoying. 1997. Commercial orchard evaluation of the new Cornell-Geneva rootstocks. Acta Hort. (in press)


Progress 01/01/95 to 12/30/95

Outputs
The commercialization of 3 previously released Geneva apple rootstocks (G.11, G.30 and G.65) is proceeding with the planned release of 2 more stocks in 1997 (G.16 and G.210). In mid 1995 it was discovered that several years ago, misidentified G.65 and G.11 plant material was sent out from Geneva to commercial nurseries. This has necessitated the destruction of existing commercial stoolbeds and the reintroduction of these two stocks. As a result the commercial sale of these two stock will be delayed until 1999. Early results with CG rootstock performance from NY trials and the nationwide NC-140 trials show: 1. G.65 has given a tree smaller than M.9 and has been too weak with insufficient leaf area for optimum fruit size with 'Empire' and 'Liberty' as the scions. In addition G.65 has generally had lower efficiency than M.9. It is likely that this rootstock may only be useful with very vigorous scion cultivars. It may also require irrigation for optimum fruit size. 2. G.11 was not included in the older trials with Empire but this stock has performed as well as M.9 through year 4 in the Liberty trails. Trees appear to be about M.26 size. 3. G.30 has given a tree about the same size as M.7 but much more productive. After 5 years trees on G.30 have had double the yield of trees on M.7 with yield efficiency as good as M.26. 4. CG.210 has given a tree similar in size and productivity to G.30 but has the added advantage of Woolly Apple Aphid resistance. This may be a significant advantage in warmer appl.

Impacts
(N/A)

Publications


    Progress 01/01/94 to 12/30/94

    Outputs
    In 1993 several of the Giessen and GM dwarf cherry rootstocks exhibited smaller fruit size and severe devitalization of tree vigor. A few accessions showed slight improvement in 1994 but others continued to decline. Pollen born NEPO viruses PNRSV and PDV were ruled out as causal agents through indexing every tree. We have no concrete evidence that genetic incompatibility is the cause but wood and bark tissue samples are being studied anatomically. Currently it is our opinion that the decline symptoms resulted from repeated heavy flowering and heavy fruit set combined with drought during the early years of the orchard. Overall the Gi 154/7 and Gi 172/7 rootstocks have shown superior performance in terms of yield, trunk growth and fruit size. A series of trials with the new Cornell-Geneva apple rootstocks was planted in 1991 in several locations in NY with Empire as the scion variety. To date three stocks have shown greater efficiency than M.9 (CG.41, CG.77, and CG.935). CG.77 appears to be smaller than M.9 while CG.41 is between M.9 and M.26. CG.935 had the highest yield and is slightly larger than M.26. CG.707 is a vigorous stock that has performed well. G.65 and CG.30 have performed below expectations. We think this could be related to the use of micro-propagation to produce these stocks. Following the severe winter of 1993/94 (-35 degrees Centrigrade), damage ratings showed some spur and scaffold branch damage on CG.13 and CG.103. Neither of these stocks has shown very good yield efficiency.

    Impacts
    (N/A)

    Publications


      Progress 01/01/93 to 12/30/93

      Outputs
      1988 ROOTSTOCK PEARS: After 6 years, Bartlett on OHxF 40 are the largest, most productive, and most efficient producers of the 8 rootstocks in the trial. 1984 APPLE ROOTSTOCK TRIAL: Spur-type Delicious on Bud.491 was very dwarfed very productive of large fruit. More P.16 and P.22 trees were killed by fire blight. Several P.1 trees were girdled by burrknots. 1987 CHERRY ROOTSTOCK TRIAL. The Giessen and GM dwarf cherry rootstocks showed the onset of a major health problem during June and July of 1993. The cause is not known, but delayed genetic incompatibility is suspected with symptoms being an early cessation of annual growth, pale, flagging of leaves, yellow-green foliage, early fruit ripening, and many unfruitful spurs. Individual trees were rated for symptoms and a narrated video tape of the above ground symptoms was made and is available. A multi-state rootstock trial was organized in 1992 (12 states) and in 1993 (11 states) to test the new Cornell-Geneva rootstocks using Liberty as the scion variety. The first EPA-approved field trial of a DNA- transformed apple clone was set in May 1993. It is a transgenic Malling 26 rootstock with a proteinase insert. The transformed clone was significantly less susceptible to fire blight in the laboratory and the greenhouse.

      Impacts
      (N/A)

      Publications


        Progress 01/01/92 to 12/30/92

        Outputs
        APPLES: 1984 Rootstock Trial - spur-type Delicious on P.16, P.22 and Bud.491 were dwarfed more than M.9; on Bud.9, C6, MAC.39 and CG.10 were between M.9 and M.26. P.18 and Antonovka 313 are very vigorous and those on Bud.490 slightly smaller than standard. 1990 Orchard Systems Trial-the slender spindle system had the highest yield and the central leader system had the lowest yield. Vertical axis and Y-trellis systems were intermediate. M.9 and M.26 the lowest. 1992 Plantings-elite CG rootstocks trials were planted in 12 states and Canadian provinces. PEACHES: After 9 years, Lovell seedling rootstocks were clearly superior to the 8 other stock systems, considering tree health, production efficiency and fruit size. CHERRIES: Hedelfingen on most of the Gisela clones produced medium-large fruits and high yields on intermediate-size trees with Gi.148/1 exceptionally productive. Colt, mazzard, and the MxM clones produced large trees with low yields; GM.9 and GM.61/1 demonstrated no commercial promise. Montmorency on GM.79 and Gi.172/7 had high mortality; Gi.195/1, Gi.148/1 and Gi.172/9 were most productive. PEARS: After 5 years, Bartlett on, OHxF 40 are the largest, most productive, and most efficient producers of the 8 rootstocks in the trial. PLUMS: After 3 growing seasons, trees on marianna 4001 are the largest. Crop on Citation approached commercial levels; trees on Damas GF 1869 suckered heavily.

        Impacts
        (N/A)

        Publications


          Progress 01/01/91 to 12/30/91

          Outputs
          The NC140 rootstock trials continued. Fire blight of rootstocks destroyed 1 P16and 1 P22 tree; all the very dwarfing stocks have now effectively "runted out" and only MAC39 appears to have potential. Under Redhaven, Lovel again was most efficient producer and continued to be rated best overall; GF1869 suckered very heavily; more split pits were observed on GF677. On heavy soil, Phytophthora killed 5/8 Montmorency/GM79, 2/8 Gil95/1 and 4/8 mahaleb SL275. Hedelfingen on Gil48/1 was outstanding for productivity and drought tolerance under load; GIL72/9 was drought sensitive under very heavy crop load, but with irrigation should be outstanding; cropping on GM9, GM61/1, Colt, mazzard and the MxM series was quite inefficient. Bartlett on Pyrus callervana seedling are dying; OHF 40, 333 and 513 were most productive in 4th leaf, although 339 has heaviest blossom.

          Impacts
          (N/A)

          Publications


            Progress 01/01/90 to 12/30/90

            Outputs
            CHERRIES: In the 4th year of the cherry rootstock trial, crop was killed by late frost. Good bloom was recorded on Gisela 172/9, Gi.148/1, Gi. 148/8 and Gi.195/1; there was no significant bloom on G.M. 9, G.M. 61/1, G.M. 79, Colt, mazzard, or the MxM series. Trees on Gi. 172/9, G.M. 9 and G.M.61/1 were distinctly smaller than those on other stocks. X-DISEASE: After artificial inoculation with the western X-disease agent, the following clones and species were resistant: PO. mahaleb, the MxM stocks, P. canescens, P. maackii, P. serotina, and some P. serrulata clones. Colt, G.M.61/1, and all P. avium, P. cerasus and P. fruticosa clones were susceptible. PEARS: All trees on Pyrus calleryana have died, apparently from winter damage. Bartlett/OHxF 333 had heavy bloom in 3rd leaf. PLUMS: Stanley trees on 7 rootstocks were planted as part of new NC-140 multi-state trial. We prepared trees on 6 more stocks for further multi-state planting in 1991; Eruni (from Sweden) is included.

            Impacts
            (N/A)

            Publications


              Progress 01/01/89 to 12/30/89

              Outputs
              In the 1984 apple rootstock trial, production efficiency of spur-type Delici on C6,P-2 and P-22 was again outstanding. Burrknots(BK) were very serious on P- 1; no BK were observed on C6,MAC-39,P-16 or P-18 and few BK on Bud.9,P-2 or P- 22. Montmorency on mahaleb, Inmil, Gisela 195/1 and Gi. 148/1 stocks were very precocious in their 3rd year. On this marginal site, 5/8 trees on Camil died, apparently from Phytophthora . Moderately heavy suckering developed from Gi. 172/7 and Gi.173/9. Significant crops of Hedelfinger sweet cherries were produced on Gisela 148/1 and Gi.195/1 in the 3rd season; no fruits were produced on Damil, mazzard, MxM- 60, MxM-46 on trees on Gi.154/7 stocks. Trees on Colt, MxM-2, MxM-39, MxM-60 and mazzard were largest, and those on Damil, Inmil and Gi.172/9 smallest. Jork 9, an M.9 OP selection, induced very heavy early production of Mutsu, McIntosh and Delicious. Unfortunately, J9 is extremely susceptible to fire blight and develops large numbers of exuberant burrknots.

              Impacts
              (N/A)

              Publications


                Progress 01/01/88 to 12/30/88

                Outputs
                NC-140 COOPERATIVE TRIALS: Apples: In the 1984 apple planting, P-1 shanks now display extremely heavy burrknotting; this stock will not be acceptable. Trees on M.4 and Bud.490 are larger than trees on M.7 and less productive. P-2, MAC-39 and C6 are most promising. Peaches: Redhaven on Lovell continues to be best combination. Redhaven on Citation was relatively little affected by drought; for the first time, this combination did not defoliate early. Suckering from Damas is unacceptably heavy. Cherries: Hedelfinger on GM 61/1 stopped extension growth earlier and had shorter internodes than on other stocks. Only 4/8 trees of Montmorency on GM 79 survived on a relatively poorly drained site. Pears: A trial planting of Bartlett on OHF selections was made. DISEASE RESISTANCES: In California, the X-disease trial is continuing, with readings expected next year. In Pennsylvania, we have had no positive readings in the Xiphinema /tomato ringspot virus transmission trials with various Prunus stocks. One replicate of a trial of Malus seedlings has been entered into the Pennsylvania TmRSV trial, and 3 additional reps have been propagated at Geneva; hybrids were derived from the susceptible Empire, MM.106, MAC-30 and MAC 39 and the immune Robusta 5, Novole, and Delicious. NEW ROOTSTOCKS: Eruni, Myro 2/5 and Myro 20-2 plum stocks were propagatged for NC-140 trial. Two MM.106 x M.27 hybrids from East Malling were recovered from field trees, virus indexed and propagated for further trial.

                Impacts
                (N/A)

                Publications


                  Progress 01/01/87 to 12/30/87

                  Outputs
                  NC-140 COOPERATIVE TRIALS: In 1984 apple planting, P-2 and MAC-39 continued to be outstanding as dwarfed trees. 'Redhaven' on Halford and own-rooted were least productive, and those on Lovell most productive. Suckering by 'Damas' was very heavy. Fruit from Damas-rooted trees ripened 3-5 days early. Plantings of 'Montmorency' and 'Hedelfinger' were made, with 17 new rootstocks included. ENVIRONMENTAL ADAPTATIONS: A cooperative trial of cherry and peach stocks for susceptibility to Western X disease was initiated in California. Thirty-five Prunus stocks were entered in a tomato ringspot virus susceptibility trial. Testing of Prunus for susceptibility to Phytophthora and Coccomyces and chilling requirements of apple stocks continued. INTERSTEMS: A 12-year trial of Delicious/Interstem/MM.106 was concluded. Trees were planted with half the length of the 20 cm interstem below ground. All M.9 interstems rooted, most of the M.27, and few of the Bud.9 and Ottawa 3. None of the interstem roots became dominant over the MM.106 root system. There were no rootstock-related differences in production efficiency. PEACH/PLUM COMPATIBILITY: Most of 11 cultivars of peaches continued to thrive on Stanley plum stock, but both 'Independence' and 'Nectared' nectarines exhibit the kind of union incompatibility typical on 'Damas'. A more extensive trial was initiated, including peach cultivars incompatible with 'Damas', and nectarine cultivars that are compatible.

                  Impacts
                  (N/A)

                  Publications


                    Progress 01/01/86 to 12/30/86

                    Outputs
                    APPLE TRIALS: In the 1983 NC-140 planting, trees on P-2 were very dwarfed andproductive. Shanks of P-1 were badly burrknotted, so much that this rootstock should be discarded. In the 1980 NC-140 planting, trees on Mark and on Ottawa 3 were outstanding; trees on MAC-24 were large, vigorous and unproductive and had numerous suckers. PEACH TRIALS: In the 1983 NC- 140 planting, Redhaven trees on Citation were very dwarfed and heavily productive, and appeared to exhibit symptoms of incompatibility. Own- rooted Redhaven and trees on GF 677 were superior to most others. Trees on Halford were least productive and were latest to drop foliage in the fall. Anchorage of trees on most Prunus besseyi clones was inadequate for general use. Madison trees on Sapa were of intermediate size, well anchored, and productive; fruits were unusually large and matured 3 days earlier than on other stocks. PEAR ROOTSTOCKS: Bartlett on OHF-69 and OHF-333 and Bosc on these stocks and OPR-40 were outstandingly productive, semi-dwarf trees; these stocks are recommended for commercial use. TESTING ENVIRONMENTAL ADAPTATIONS: Testing of Prunus stocks, especially cherry stocks, for resistance to Phytophthora cambivora and P. megasperma was continued. Evaluation of natural infection of cherry rootstock candidates with Coccomyces was continued at Geneva and in Germany.

                    Impacts
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                    Publications


                      Progress 01/01/85 to 12/30/85

                      Outputs
                      Interstems: Usually a clone which is dwarfing as a rootstock is dwarfing when used as an interstem. A conspicuous exception is CG.10, an open- pollinated seedling of Malling 8. CG.10 is as dwarfing as M.9 when used as a rootstock, but exerts no dwarfing effect when used as an interstem. Diseases: Twenty-four rootstock candidates were subjected to whole plant inoculation with Phytophthora megasperma or Ph. cambivora in July. Two selections from Germany -- Gi 196-4 and Gi 196-13 -- and two Belgian clones -- GM 9 and GM 79 -- were as susceptible as Prunus mahaleb. Two P. cerasus x P. fruticosa hybrids from Germany -- Gi 154-7 and Gi 172-7 -- were tolerant of both pathogens. Peaches on Stanley plum rootstocks were set in a site infested with TmRSV-carrying nematodes. Low Temperature Tolerance: Leaffall data on apple and cherry rootstocks and candidates were collected again. This year no differences were discerned in effect of rootstock on leaffall of apple scion varieties. Shoots of 29 cherry clones were subjected to programmed freezing in early winter. Colt and Prunus maackii were very sensitive; P. fruticosa clones and P. fruticosa x P. cerasus selections were highly tolerant to -25C. Propagation: Hormone and bottom heat requirements for softwood cuttage of 45 Prunus clones were studied. Clones with P. fruticosa parentage were especially difficult. Most P. besseyi selections rooted readily, but establishment required fungicide drenches.

                      Impacts
                      (N/A)

                      Publications


                        Progress 01/01/84 to 12/30/84

                        Outputs
                        New Plantings: Three trials sponsored by NC-140 were planted: (1) Redhaven peaches on 9 stocks, include own-rooted; (2) Rome Beauty apples on 11 interstem systems with MM.111 roots; (3) Starkspur Delicious on 19 dwarfing clonal stocks, including own-rooted. Peaches: in 2 trials of stocks under Madison, Sapa and 2 clonal selection of Prunus besseyi made very productive, mid-sized trees. Fruit on Sapa-rooted trees was uniformly large and Sapa-rooted trees were well-anchored. Apricots: Two P. besseyi stocks continued to perform well in second test under Alfred; these are proposed for introduction in 1987. Dwarf apples: After 5 years under Starkrimson Delicious, P-22, Bud. 146 and Bud. 491 and M.27 produced trees of similar productivity and diminutive size. Trees on M.9, Ottawa 3, Bud. 9 and P-2 were similar. Trees on M.26 and Bud. 490 were similar. Some trees on all stocks have been lost to fire blight. Bud. 146 stocks are extremely brittle. Propagation: K-14, a trunk stock with unusually long chilling requirement, has traditionally been propagated by grafting and has been regarded as impossible to root. After 2 weeks etiolation and then 2 weeks normal growth, cuttings of K-14 rooted 70% under intermittent mist.

                        Impacts
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                        Publications


                          Progress 01/01/83 to 12/30/83

                          Outputs
                          Apples: In the 5th year of a Starkrimson Delicious trial of new dwarfing stocks, P-22 and Budagovsky 54-146 were as dwarfing as M.27; however, Bud.146 is so brittle as to be of little value. As an unbudded stock, P-22 leafs out in the spring as late as M.26; we have not discerned any rootstock effect on budbreak of the scion variety. Pears: In a trial started in 1971, under both Bosc and Bartlett, OHF 69 and OHF 333 stocks have produced semi-dwarf, precocious, heavily productive, well-anchored trees, while none of 9 clonal quince stocks have performed adequately. Apricots: In a 11-year trial, Alfred on a P. besseyi x apricot hybrid produced dwarf, precodious, productive, well-anchored trees. However, almost all these trees were killed by low temperature in December 1980. Trees on Sunglo seedlings were very large and productive; the fruit mature late. A P. divaricata X P. spinosa amphidiploid appeared promising. A rootstock trial of the following Old Home x Farmingdale rootstocks was planted this year in Niagara Co., Seneca Co., Oswego Co., and Ulster Co.: OHF 51, OHF 97, OHF 217, OHF 282, and OHF 333. Trees on Bartlett seedling rootstocks were planted as checks. The scion varieties used include Bartlett, Bosc, Highland and Seckel.

                          Impacts
                          (N/A)

                          Publications


                            Progress 01/01/82 to 12/30/82

                            Outputs
                            In 1982, the senior leader of this project, Dr. J.N. Cummins, spent a sabbaticalleave with Dr. Gruppe, Giessen, Germany where he investigated techniques and philosophy of breeding new stone fruit rootstocks, especially stocks for tart cherries. The annual meeting of the USDA's Northcentral Regional project, NC-140, was held at the Univ. Ill. and was attended by Dr. R.C. Lamb. Yield and tree size data were collected from 7- yr-old interstem trees, Starking/M.9/MM.106. The experiment is a comparison of size-controlling effects of several strains of M.9, both virus-infected and virus-tested. In 1971, 13 semi-dwarf and semi-vigorous rootstocks were budded with spur-type Delicious. For the 12-year period, 1971-82, trees on MM.106 have had the best production efficiency. For trees planted at optimum spacing in 1976, greatest accumulated per-hectare yields have been for trees budded on M.9 roots. M.26 produced intermediate yields and MM.106, least.

                            Impacts
                            (N/A)

                            Publications


                              Progress 01/01/81 to 12/30/81

                              Outputs
                              Whether differences among strains of M.9 rootstocks are caused by genetic variations or by differences in virus contents is being examined with trellised trees of Empire/M.9 and with interstem trees of Starking Delicious/M.9/MM.106. After 6 years, we have not observed differences in yield, tree size, or production efficiency attributable to strain variations. We now have 19 subclones of M.9 in our collection, being propagated for further evaluation. Whether rootstock has an effect on phenology of the scion cultivar, especially as to blossom time, is being studied in cooperation with Dr. Robert Seem (Plant Pathology). Spring budbreak, flower bud development, and flower opening of spur-type Delicious are being compared on 15 rootstocks, including Robusta 5 (very early) and Malling 16 (very late) at Geneva and in 2 locations in Wayne county. No differences were observed in the first 2 seasons. In a block of spur-type Delicious set in 1971, MM.106 has been outstanding for production efficiency, compared to 12 other semi-dwarf and semi- vigorous stsocks. In a block set in 1976 to compare efficiency of stock systems, at optimum spacing, accumulated bu/acre were M.9=1016 bu., M.26=996 bu and MM.106=789 bu. In addition to Sugar crab, PI 286613, and a M. micromalus selection, we identified a selection of M. honanensis that is nonpreferred by meadow voles. Testing for vole resistance is being extended.

                              Impacts
                              (N/A)

                              Publications


                                Progress 01/01/80 to 12/30/80

                                Outputs
                                Meadow Vole Resistance: A method for evaluating vole preferences among apple shoots under orchard conditions was devised. Among 25 clones examined 'Sugar Crab', M. X micromalus and M.X sublobata PI 286613 were least preferred while M.9 and 'Golden Delicious' were highly preferred, "No-Choice" testing was not successful. Plantings: A planting of spur-type 'Delicious' on 10 stocks was made at Sodus; this is part of the NC-140 program. Also at Sodus, 900 trees of 'Northern Spy' on some 300 advanced selections from the Geneva rootstock breeding program were set for production evaluation. Interstems: In a 1976 planting of 'Starking Delicious' interstems on MM.106 roots, after 5 growing seasons, trees with M.27 interstems are slightly smaller than those with M.9, Buc.9 or Ottawa 3 interstems.

                                Impacts
                                (N/A)

                                Publications


                                  Progress 01/01/79 to 12/30/79

                                  Outputs
                                  Accessions: Six new rootstock selections were received: 3 of Trusevich's selections (Krasnodar, USSR); MB-4 from Finland; Bemaldi (BM 342) from Balsgard, Sweden; and Westwood's OAR-1 from Oregon. Two virus-free clones of M.9 were received from Germany and Budagovsky 9 cleaned up by the Canadian PEQ station, was added. Interstems: In a 2 year-old planting, we have lost about 10% of Delicious /M.27/MM.106 and Delicious/Ottawa 3/MM.106 for causes not yet determined. We noted purple foliage on many of these trees in Autumn 1978; in Summer 1979, the entire interstem was dead, with both scion and rootstock apparently healthy. We have had no mortality of this type with M.9 or Bud.9 interstems in the same planting. Bud.491 has continued to look promising as an interstem; trees with interstems of CG.10 continue to be vigorous. Viruses: Tomato ringspot virus continues to appear to be associated with the union necrosis and decline syndrome of trees of Delicious, Jerseymac and Tydeman's Early on MM.106. In 2 affected blocks in the Hudson Valley, we planted liners of 10 rootstock clones as inarches; grafting in April was 90% successful. We did not recover TmRSV from leaves of any of the inarches, including the control, MM.106. Scion-rooted trees developed classical union necrosis but have survived as quite unproductive trees.

                                  Impacts
                                  (N/A)

                                  Publications


                                    Progress 01/01/78 to 12/30/78

                                    Outputs
                                    In trials at Newfield and Geneva, trees of N.Spy/interstem/MM.lll were planted in 1975 to test stock candidates for induction of early fruiting and for tree size control. Trees with interstems of Budgaovsky 57-491 (Bud. 491) began bearing as early and were smaller than Spy/M.9/MM.lll controls. Trees of Spy/CG.10/MM.lll were larger and less fruitful. Trees with interstems of Bud. 54-118 or Bud. 57-490 were quite vigorous; the Spy/Bud. 490/MM.lll trees were moderately fruitful. After 4 growing seasons, we can distinguish no significant differences in tree stature or fruiting pattern in plantings of N.Spy/interstem/MM.106, in which the interstem is either (1) M.9 (carrying CLS, ASP and ASG latent viruses); (2) M.9A (carrying the same latents, but apparently genetically not identical with M.9); (3) M.9-Ohio (virus-free); or (4) M.9-Ohio inoculated with M.9. In a 1970 planting of Mutsu, the original Malling-Merton series was compared with M.7, M.26 and Merton Immune 779 stocks. Trees on MM.105, MM.110, MM.111, MM.113, MM.114 and MI 779 were largest; those on MM.101, MM.102 and MM.106 were intermediate; on M.7, small; and on M.26 dwarfed. Trees on M.26, MM.106, MM.102, M.7 and MI 779 were relatively efficient producers. Fruit on M.26-rooted trees matured 3-4 days earlier than on other stocks; all M.26-rooted trees required staking.

                                    Impacts
                                    (N/A)

                                    Publications


                                      Progress 01/01/77 to 12/30/77

                                      Outputs
                                      INTERSTEMS. A new planting of Delicious/int/MM.106 was established at Geneva using Bud. 9, 0. 3, M.27 and either virus-free or virus-infected M.9 as the interstems. Site was solid-fumigated before planting. Mechanical strength of unions of 18-yr-old Golden Del. with M.8, M.9 and some vigorous clonal stocks was examined on test bench. The M.8 and M.9 unions were more susceptible to stress than those of the more vigorous stocks; however, the reduced wind resistance of the smaller trees with M.8 and M.9 interstems made them little more susceptible to wind damage than were the large trees. There was no evidence that the M.8 and M.9 unions would be susceptible to damage from normal mechanical harvesting. LOW TEMPERATURE TOLERANCE. Standardized artificial freezing procedures now give results closely tied to field obsns. Shoots of previous summer's growth ca. 6-8 mm diam, are placed in polythene bags and frozen at Triangle equal to minus 1.6 C degrees/hr; samples are removed at 4 degrees intervals, usually from about minus 25C through minus 43C and thawed gradually. The shoots are held under intermittent mist at ca. 20C for approx 3 weeks, then examined for regrowth and tissue damage and T(50) established. GA is applied to shoots tested before normal chilling requirements have been satisified. In preliminary obsns, mid-Dec. T(50s) of hybrids which matured foliage early were ca. 3C degrees lower than those of late-maturing hybrids in R5 progenies, mid-Dec.

                                      Impacts
                                      (N/A)

                                      Publications