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Improving Economic and Environmental Sustainability in Tree-Fruit Production Through Changes in Rootstock Use
Department of Horticulture
The information developed through this project is vital to the economic success of the North American fruit industry by preventing mistakes by the industry and identifying rootstocks that are more productive and thus more profitable than existing rootstocks. This project has already become the primary source of information on rootstocks for the North American tree-fruit industry in each fruit production region of the continent.
The primary outputs of this project have been and will continue to be unbiased information on the field performance, stress tolerance, and propagation of fruit tree rootstocks in different climates and soils across North America. This is measured by the continued flow of information to fruit growers and nurserymen through both oral presentations and publications from each of the uniform multi-state orchard plantings and from rootstock development and evaluation work done by the individual cooperators.
Since the last project revision, this project has published 17 refereed reports on nine multi-state rootstock trials. Publications from individual researchers or groups or researcher under the objectives of this project are also an important measure of success, and since the last rewrite of this project, there have been more than 140 publications by individual researchers.
Outcomes or projected Impacts: The expected outcome of this project is a more profitable and competitive tree fruit industry in North America. To remain competitive in the world fruit market, fruit growers need to replant old orchards, but the high level of investment required and the long-term nature of the investment to plant new orchards require that growers make sound research-based decisions of which rootstock and cultivar to plant. If the wrong rootstock is used, it can result in low production and reduced profitability or in the worst case, death of the trees and significant economic losses. If superior rootstocks are used, yields, fruit quality and hence profitability can be improved. As results from this project are made available, the fruit industry has made and will continue to make changes in the rootstocks used.
The impact of this project will be measured by the changes the fruit industry makes in adopting new improved rootstocks and by the prevention of serious rootstock failures and associated economic losses. This will be measured by surveying rootstock propagation nurseries to determine trends in which rootstocks are being planted by North American fruit growers. In addition, data from the National Agricultural Statistics Service http://www.nass.usda.gov/Census of Agriculture/index.asp is analyzed to determine planting trends. The Census of Agriculture is published every five years and contains valuable data. This is then incorporated into our impact statements. Impacts are posted on our website http://www.NC140.org
Many individual states also conduct tree fruit planting surveys periodically that are utilized to track planting trends of dwarfing tree fruit rootstocks and will be utilized to measure the impact of NC140 in individual states.
2009 Project Description
Reported research results at state and regional conferences.
The 2009 growing season averaged 0.4 F lower than normal. The state apple crop was about 60% of normal due to a lighter bloom from the biennial effect of the year following a heavy crop and to poor pollination caused by a cool wet spring. Fruit size was often smaller than desired due to low seed number, though adequately pollinated fruit were of sufficient size. Fruit color was outstanding because of the cooler-than-normal July and August.
The 1999 apple trial with Fuji as the scion was terminated at the end of 2008 after collecting data on winter injury. There were no significant differences among either the dwarfing or semi-dwarfing rootstocks with regard to either blackheart injury in the xylem or winter injury on the scions. The percent winter injury on the bark of M.9 NAKBT337 and Supporter 4 was significantly higher than that observed for the other rootstocks.
In the 2002 apple trial with Buckeye Gala as the scion, significant differences were observed for cumulative yield, 2009 yield, fruit weight, and trunk cross-sectional area (TCSA), but no differences were observed in tree mortality, cumulative yield efficiency, or number of root suckers. The cumulative yield was greatest for scions on P.14 and M.9 Burgmer 756. P.14 and the two B.9 rootstock strains have produced the largest and smallest trees, respectively.
In the 2003 apple rootstock and physiology trials with Golden Delicious as the scion, mortality, cumulative yield, 2009 yield, TCSA, and cumulative yield efficiency varied significantly among the rootstocks. The highest cumulative and annual yields were observed on PiAu 56-83, which also had the largest fruit size and trunk cross-sectional area.
In the physiology trial, there was no significant interaction between crop load treatments imposed in 2008 and rootstock. However, 2009 yield, fruit weight, and crop density were significantly affected by crop load treatments imposed in 2008, while TCSA, number of flower clusters per cm2 of limb cross-sectional area, and cumulative yield efficiency were not affected. Yield and yield/TCSA were positively correlated with fruit/TCSA in 2008, while fruit weight was negatively correlated. In 2009, yield, yield/TCSA, fruit weight, and flower clusters/limb cross-sectional area were negatively correlated with fruit/TCSA treatments in 2008.
The 2009 peach rootstock and physiology trials were planted.
Wolfe, D., D. Archbold, J. Johnston, and G. Travis. 2009. Rootstock Effects on Apple and Peach Tree Growth and Yield. 2009 Fruit and Vegetable Crops Research Report. University of Kentucky College of Agriculture, Agricultural Experiment Station PR-603: 13-15.