NORTH CENTRAL REGIONAL RESEARCH PROJECT NC-140
ROOTSTOCK AND INTERSTEM EFFECTS ON POME- AND STONE-FRUIT TREES
October 1, 1997, to September 30, 2002
The NC-140 Regional Research Project is designed to address a number of high-priority areas within the North Central Region as well as other parts of North America. This project seeks to enhance economically and environmentally sustainable practices in temperate fruit production by focusing on rootstocks. The NC-140 project addresses specifically several priorities outlined in the handbook entitled "Establishing Priorities for Regional Research: The Process" (September, 1996). Those priorities are labeled 4.2-D (1, 2, and 3), 4.3-D (1, 3, 4, and 5), 4.4-D (1, 2, 3, and 4), and 4.7-D (2) and fit into the seven cross-cutting issues.
With the increasingly competitive international market, the growing demand for higher quality fruit by consumers, the strong pressure to reduce chemical use, and an ever increasing need to enhance the economic efficiency of production, tree-fruit growers must look to alternative, economically and environmentally sustainable management schemes of production. Growers who want to stay profitable must establish high-density plantings with much smaller trees using new cultivars. These high-density plantings may cost 10 to 20 times more to establish than low-density plantings, thus greatly enhancing the economic risk. Potential returns of high-density plantings, however, far exceed those of low-density plantings, particularly during the first 10 years, often returning the grower's initial investment much sooner than the less-costly, low-density plantings. The central component of high-density systems is the rootstock. It is this part of the tree which provides dwarfing and allows for high-density plantings. As part of the tree, rootstock influences many factors in addition to tree size, particularly productivity, fruit quality, pest resistance, stress tolerance, and thus profitability.
As the industry moves from low- to high-density plantings, several rootstock-related problems must be addressed. New pome- and stone-fruit rootstocks cannot be recommended without reservations until there is sustained research as to soil and climatic adaptability, root anchorage, size control, precocity, productivity, pest resistance, and propagation. In general, field testing of rootstocks in an orchard setting requires a minimum of ten years to assess accurately the potential for improved profitability, reduction of inputs, and enhancement of production efficiency. With year-to-year variation in weather, this time span is necessary to obtain a true indication of rootstock performance.
The establishment of the NC-140 technical committee enabled researchers from IL, IN, IA, KS, KY, MA, MI, MO, NY, OH, and WI to develop a coordinated effort in apple rootstock research through the uniform testing of rootstocks and multiple genetic systems, and to discuss critically, evaluate, and coordinate other rootstock research. Such efforts allow the results to be interpreted directly in the various geographical regions. Since NC-140 is the only regional committee focusing on apple rootstock problems, researchers from AR, CA, CO, GA, MD, ME, MN, NJ, NC, OR, PA, SC, SD, TN, UT, VT, VA, WA, and WV (USDA-Kearneysville) have since joined the committee. The Canadian provinces of BC, NB, NS, ONT, and QUE, as well as a site in Australia are participating as cooperators in an effort to share results and plan a coordinated research program. Stone-fruit crops were included in the project in its 1982 revision.
A stable tree-fruit industry based on economically and environmentally sustainable orchard systems is one of the primary goals of NC-140 research. Prior to organization of NC-140, knowledge of rootstock and multiple genetic system performance and adaptability had to be obtained from a number of unrelated studies. The lack of common planting materials, spacing, and cultural procedures made comparison of the results of these studies difficult, and slowed the accumulation of knowledge that could be applied by orchardists. These difficulties coupled with the industry shifting to smaller trees with closer spacing resulted in serious planning and management errors. Also, such unrelated studies have been incomplete or slow in evaluating rootstock tolerances to biological, environmental, and edaphic stresses. Through the uniform cooperative testing undertaken by NC-140, new rootstocks can be exposed quickly and systematically to widely varying soil and climatic conditions to shorten the time necessary for thorough evaluation.
Each rootstock may react differently with a particular scion cultivar and each rootstock/cultivar combination may react differently under a particular training system. This interaction makes it necessary to field test rootstock/cultivar/system combinations that may be profitable for North American growers. Orchard systems must be designed to meet the specific needs of each fruit crop. In northern Europe, where labor is expensive and new land is unavailable, the apple and pear industries have developed orchard systems with a high number of trees per acre, with all tree maintenance occurring from the ground. In past years, the free-standing, central-leader system has been very profitable for North America, particularly with the weak, spur-type Delicious cultivar. As labor became more expensive and the list of profitable cultivars started changing rapidly, some North American growers began converting to smaller, high-density orchard systems. However, no entire system can be taken from one area and implemented in another without modifications. Growth characteristics of cultivars and rootstocks under North American conditions are much different than in northern Europe where most high density systems were developed. Also, tree response under a particular management system in different areas in North America can vary greatly. These problems require that various systems be tested under many North American climates and that modifications of training and pruning techniques be developed to match local growing conditions.
Any newly developed rootstock must exist ultimately as an integral part of a total orchard-management system. Current economic trends make production efficiency of new scion/rootstock combinations under various cultural-management systems one of the most important factors that must be evaluated thoroughly before specific combinations are recommended for large-scale plantings by fruit growers. A uniform apple orchard systems trial was established in 1990 by the NC-140 Committee and is currently under evaluation.
Knowledge of the propagation characteristics of newer rootstocks and reasons for incompatibility between cultivars and rootstocks is a continuing need. Some promising pome- and stone-fruit rootstocks presently cannot be considered for commercial use because of difficulty in rooting clonal material using existing techniques. Alternative methods of propagation only recently have begun to offer solutions to these problems. Using different propagation methods such as hardwood or softwood cuttings, which are not commonly used, may be very effective for mass production of some of the rootstocks that do not propagate well by conventional means. Expanded research with micropropagated plant material needs to be done to anticipate potential problems before widespread adoption by the fruit industry occurs. These techniques may also allow early screening of plant material for desirable characteristics such as disease and insect resistance.
With many new rootstocks available for growers and nurseries, the need to be able to identify these plants via morphological and biochemical methods is imperative. Some rootstocks stand out morphologically because of a difference in bark and leaf characteristics, but most do not. Developing methods for use in the laboratory and in the field will help all who use rootstocks to decrease the likelihood of planting mistakes.
If the pome and stone fruit industry is going to continue to change to meet the needs of the consuming public, new genetic material will need to be incorporated into existing material to enhance performance of rootstocks. Using both traditional plant breeding and genetic engineering methods, researchers can incorporate insect and disease resistance into existing rootstock material, as well as develop rootstocks with enhanced horticultural performance. Obtaining genetic material from research programs from throughout the world and testing those new rootstocks through the NC-140 cooperators has been an integral part of the project. Clonal materials of different rootstocks have been obtained from many countries since the inception of the NC-140 project and will continue. The 1994 apple rootstock trial contains rootstocks from England, Poland, Russia, and the United States. As a result of this planting, one of the Russian rootstocks is being propagated and sold extensively to orchardists in North America.
Low temperatures, soil adaptability, and susceptibility to pests limit the use of existing rootstocks, and potentially will limit the adaptability of some new rootstocks within the North Central Region and across North America. Understanding how different rootstocks respond to biotic and abiotic stresses can lead to recommendation for use or non-use under certain orchard conditions. Such studies must include factors contributing to stress tolerance, development of practical means for controlling various stresses, or development of rapid means for screening potential rootstock candidates for susceptibility to various stresses. A better understanding of the physiological mechanisms behind these responses may allow for development of cultural practices which can relieve the detrimental effects of stress.
Cooperative testing of new and existing rootstocks by NC-140 researchers continues to generate interest and support from the fruit and nursery industries. This interest has resulted in industry financial support for the establishment of cooperative plantings, grants for state rootstock research, and propagation of trees for several of the NC-140 plantings. It is estimated that over the term of the current project (1992-97), nearly $2,000,000 will be received to support its research from sources other than universities, Hatch funds, and RRF funds, and more than one half of this total will come from grower organizations. A compelling need exists to continue the present coordinated studies and to initiate new studies on a regional basis for both pome and stone fruit rootstocks as new plant materials are made available. Continued testing will provide a thorough evaluation of promising rootstocks, multiple genetic systems, and planting and training system efficiencies. This research project has led and will lead continuously to sound recommendations to growers and nurseries based on widespread knowledge of adaptability and performance of the plant material.
RELATED CURRENT AND PREVIOUS WORK:
Reports summarizing field observations of rootstock performance over many years (e.g., Barritt et al., 1995; Rom, 1980; Simons, 1984) indicate that many rootstocks have variable performance and no single rootstock is widely adaptable to the range of conditions in North America. Thus, a series of NC-140 trials has been established throughout a wide range of climatic and edaphic conditions. A 10-year apple interstem trial (Ferree, 1983; Simons et al., 1986) and a 10-year apple rootstock trial evaluating nine rootstock clones, including tree size and yield performance (NC-140, 1991a), location effects (NC-140, 1991b), nutrition (Rom et al., 1991), winter injury (Warmund et al., 1991), fruit maturity (Autio et al., 1991), and carbohydrate partitioning (Strong and Azarenko, 1991), have been reported. A 10-year apple rootstock trial was concluded, where the effects of rootstock on survival, tree size, and cropping (NC-140, 1996a; NC-140, 1996b), horticultural characteristics (NC-140, 1996c), bud development (Hirst and Ferree, 1996; Conrod et al., 1996; Rom, 1995), dietary fiber (Gheyas et al., 1996), fruit ripening and quality (Autio et al., 1996), and winter injury (Warmund, et al, 1996) were reported. A 10-year cherry rootstock trial reported effects on growth and cropping (Perry, et al., 1996), and a 10-year peach rootstock trial has been completed (currently in process of publication). When taken together, these findings clearly indicate the need and value of uniform testing in diverse environments in order to identify those rootstocks which are either acceptable or unacceptable for the tree fruit industries.
Fruit-tree rootstock breeding programs have been ongoing for more than 25 years in the United States, Poland, Sweden, Russia (and the USSR) (Beckman, et al., 1996; Cummins and Aldwinkle, 1982), and in other European countries (Fisher, 1996; Webster, 1996) to meet the worldwide demand for new pome- and stone-fruit rootstocks. A large amount of new rootstock material recently has been introduced and will be available in the near future (Barritt et al, 1990; Webster, and Tobutt, 1994). There are a number of other rootstocks that may be available in the next few years that are showing good potential in early trials but which have not been tested adequately to draw firm conclusions (Rom, 1988).
Propagation characteristics have been studied for many fruit tree rootstocks (Howard, 1987), and extensive research has been done on graft characteristics of many apple rootstock/scion combinations (Warmund et al., 1993; Warmund and Barritt, 1994). Micropropagation of apple rootstocks is an important step in accelerating a uniform supply of plant material for field performance studies (Welander, 1988; Howard, 1987); however, little is know about the long-term performance of micropropagated rootstocks (Quamme and Brownlee, 1993).
The identification of rootstock cultivars can accomplished by both traditional morpholocial techniques such as fruit morphology (Embree, 1995), or shoot and leaf morphology (Garner, 1946), or biochemical methods such as isozyme analysis (Mendez et al., 1986), electrophoresis of protein extracts (Huang et al., 1983), and other molecular techniques (Foolad et al., 1995; Simon and Weeden, 1992). NC-140 members are studying alternative biochemical techniques which may enhance repeatability and be economical.
Cold hardiness and winter injury of various fruit-tree rootstocks have been studied (e.g.,Warmund et al., 1991; Warmund et al., 1996), and it has been hypothesized that rootstock may affect scion winter hardiness by affecting the date of terminal bud set (Conrod et al., 1996; Rom, 1995) or the induction of early scion acclimation (Warmund et al., 1996). Rootstock waterlogging tolerance and response to water deficit stress (e.g., Anderson, et al, 1984; Olien and Lakso, 1986; Larson et al, 1988) and the interaction of rootstock and soil type (Fernandez et al., 1995) have had limited study. Other edaphic stresses also have been investigated in relation to rootstock tolerance, such as salinity (Therios and Misopolinos, 1989), alkalinity (Egilla and Byrne, 1989), soil acidity and related mineral toxicities (NC-140, 1991c), and soil physical limitations (Fernandez et al., 1995; Perry, 1987). Some economically important biological stresses of rootstocks being investigated include phytophthora root rot (Mircetich and Browne, 1989; Wicks, 1989), fireblight (Ferree et al., 1988), nematodes (Melakeberhan et al., 1994), and peach tree borer (Reilly et al., 1987). Also of interest are natural sources that offer stress tolerance or avoidance for the tree, such as mycorrhizal fungi (Morin et al., 1994). With the introduction of interspecific hybrid cherry and apple rootstocks, sensitivity to virus may become a problem (Lang et al., 1996).
1. To evaluate the performance of pome- and stone-fruit rootstocks in various environments and under different management systems.
2. To assess and improve asexual propagation techniques of pome- and stone-fruit rootstocks.
3. To improve the ability to identify pome- and stone-fruit rootstocks through morphological, biochemical, and genetic differences.
4. To develop new and better pome- and stone-fruit rootstocks through breeding and genetic engineering, and to acquire new rootstocks from breeding programs in other parts of the world.
5. To determine biotic and abiotic stress tolerances of pome- and stone-fruit trees in relation to new and existing rootstocks.
Objective 1: To evaluate the performance of pome- and stone-fruit rootstocks in various environments and under different management regimes.
To evaluate improved rootstock material and climatic and edaphic factors as related to tree performance, present replicated and randomized uniform plantings will be maintained, and new plantings will be established across North America under NC-140. Promising new and existing rootstocks and multiple genetic systems possessing desirable characteristics have been or will be selected. They will be evaluated with respect to precocity, productivity, size control, anchorage, suckering, pest resistance, adaptability, and production efficiency.
To provide a more thorough knowledge of tree performance, studies will be conducted to evaluate the performance of various orchard systems, including different cultivars on new and existing rootstocks and multiple genetic systems under various high-density orchard management systems. These systems will be evaluated as to precocity, productivity, ease of management, and production efficiency.
These plantings will be maintained and data will be collected according to specific uniform guidelines established by the technical committee. For each trial, data to be collected include a preplant soil test, weather, suckering, tree growth as measured by changes in trunk cross-sectional area, tree height, canopy spread, earliness of bloom, yield, and fruit size. Data will be transmitted annually to trial coordinators in Oregon (1988 pear rootstock), Massachusetts (1990 apple cultivar/rootstock), Virginia (1990 apple rootstock), Virginia (1990 apple systems), New York (1992 apple rootstock), New York (1993 apple rootstock), Virginia (1994 dwarf apple rootstock), Virginia (1994 semidwarf apple rootstock), South Carolina (1994 peach rootstock), British Columbia (1998 cherry rootstock), and New York (2000 apple rootstock). Standard statistical analyses will be performed on all data and will be summarized for joint publications after five and 10 years of testing.
Plantings being maintained for evaluation or proposed are as follows:
(a) Uniform rootstock trials for sweet and sour cherries were established in 1987 and 1988. The sweet cherry trial tests the performance of Bing (CA, CO, WA, OR, UT, MT, and BC) and Hedelfingen (MI, MD, NY, and ONT) on GI.148/1, GI.154/4, GI.154/7, GI.169/15, GI172/7, GI.173/9, GI.195/1, GI.196/4, GM.9, GM.61/1, GM.79, MxM.2, MxM.39, MxM.46, MxM.60, Colt, and Mazzard seedling (standard control) rootstocks. The sour cherry trial tests the performance of Montmorency (AR, KS, MI, NY, UT, WI, MT, NJ, OR, PA, and ONT) on GI.148/1, GI.173/9, GI.195/1, GI195/2, GI.196/4, GI.196/13, GM.9, GM.61/1, GM.79, MxM.2, MxM.39, MxM.46, MxM.60, Colt, Mazzard seedling, and Mahaleb seedling rootstocks. Tree size (trunk cross-sectional area, tree height, canopy spread), yield, yield efficiency, and fruit size will be measured each year by each cooperator. Further, fruit firmness, soluble solids, cracking, resistance to pitting and bruising, storability, and the development of off flavors will be evaluated (OR). Beginning in 1997, several sites will conduct a secondary study of the effects of pruning severity on fruit size of the GI rootstocks by splitting the plots (MI, NY, OR, and WA).
(b) A uniform rootstock trial for pear was established in 1988 at 15 locations (AR, CO, KY, NY, MD, OH, two in OR, two in WA, WV, BC, NS, and two in ONT). Depending on environment, sites are testing the performance and adaptability of two cultivars (selected from d'Anjou, Bosc, Comice, Clapp's Favorite, Magness, Harrow Delight, Maxine, Red Bartlett, and Bartlett) on OHxF.40, OHxF.217, OHxF.333, OHxF.339, OHxF.513, EM Quince C clones, Pyrus calleryana seedling, and P. betulaefolia seedling rootstocks with Bartlett seedling serving as the standard for comparison. Tree size (trunk cross-sectional area, tree height, and canopy spread), yield, yield efficiency, and fruit size will be measured each year of the project. Additionally, characteristics, such as anchorage and longevity, will be appraised.
(c) Apple rootstocks plantings through 1984 only evaluated the performance of one cultivar on the candidate rootstocks. To gain further information on rootstock performance and the potential interaction between scion cultivar and rootstock, a coordinated cultivar-by-rootstock trial was planted in 1990 at 16 locations (CO, GA, IN, IA, two in KS, KY, ME, MA, MI, OH, TN, PA, UT, VA, and QUE). This trial consists of all combinations of Smoothee Golden Delicious, Nicobel Jonagold, Empire, and Law Rome on M.9 EMLA, B.9, Mark, O.3, and M.26 EMLA. Additional cultivars were included for local or regional comparison: Chieftain (IA), Jonathan (IA), Liberty (KY), McIntosh (ME, MI, PA, and QUE), Stayman (PA and VA), and York (PA and VA). Also, additional rootstocks were included at a few sites: M.7 EMLA (GA), M.27 EMLA (IN and KS), and P.22 (IN, KS, and KY). Tree size (trunk cross-sectional area, tree height, and canopy spread), yield, yield efficiency, fruit size, suckering, and mortality will be measured each year of the project. At the termination of the project, horticultural characteristics, such as ease of training, will be rated. In addition to the standard average fruit size assessment, size distribution also will be evaluated (ME and VA).
(d) In 1990, an apple rootstock trial with the cultivar Royal Gala was planted in nine locations (IL, MI, MN, NY, NC, VA, WA, ONT, and QUE). Rootstocks include M.27 EMLA, M.9 EMLA, M.26 EMLA, MAC.39, P.1, O.3, B.9, and Mark. Trees are trained as tall slender spindles. Evaluations will follow guidelines similar to the previous apple rootstock trial.
(e) A uniform orchard systems trial was established in 1990 at 9 locations (IL, MI, MN, NY, NC, VA, WA, ONT, and QUE) utilizing the most promising rootstocks from the 1980 and 1984 apple rootstock trials. Cultivars included are Empire and Jonagold (IL, MI, NY, ONT, and QUE), Empire and Earli-Red-One Delicious (MN, NC, and VA), and Fuji and Braeburn (WA). The rootstock used depended upon the orchard system and are as follows: central leader -- Mark and M.26 EMLA; slender spindle -- Mark, B.9, and M.9 EMLA; and vertical axis -- Mark, O.3, M.9 EMLA, P.1, and M.26 EMLA. Orchard systems variables included are tree density, pruning and training, and support systems. In addition to data on the relative yield and management efficiency of the systems under different environmental conditions, it will also be possible to determine the separate contributions of rootstock and training/pruning to the overall production efficiency of the orchard management system. Cooperators will follow uniform guidelines of tree management and data collection, similar to cooperative rootstock trials. All sites will collect data on tree size (trunk cross-sectional area), yield, yield efficiency, and fruit size. Further, fruit quality will be assessed (AR, NY, and QUE), mineral nutrition will be monitored (AR, NY, and ONT), storability will be determined (MI and QUE), light interception within the canopy will be measured (AR, NY, WA), and water relations will be evaluated (MI).
(f) In 1990, a plum rootstock trial with Stanley as the scion was planted in four locations (IN, KY, MI, and NY). Also, Valor (MI) and Fellenburg (OR) were used as scions in one location each. Rootstock include Myrobolan seedling, Lovell, Marianna 2624, Marianna 4001, GF.8/1, GF.8/31, GF.8/677, Myrobolan 29-C, Citation, EMLA Pixy, Brompton, and St. Julian A. Growth and production efficiency will be evaluated in a manner similar to the previous apple rootstock trials.
(g) In 1992, apple rootstock trials in three size categories with Liberty as the scion cultivar were planted in 13 locations (AR, GA, IL, IN, ME, MI, MO, NY, VT, WA, NS, QUE, and ONT). Dwarf plantings included CG.13, KSC.28, CG.202, CG.11, CG.65, and CG.29 and M.26 EMLA and M.9 EMLA as standard controls. Semidwarf plantings included CG.30, CG.210, CG.707, CG.222, CG.521, and CG.179 and MM.106 and M.7 EMLA as standard controls. Vigorous plantings included CG.5, CG.934, CG.189, CG.239, Pleaf, CG.96, CG.253, CG.602, and CG.2 and MM.111 as a standard control. Evaluation of growth and production efficiency will be conducted as in other apple rootstock trials.
(h) In 1993, apple rootstock trials in three size categories with Liberty as the scion cultivar were planted in a total of 11 locations. Dwarf plantings (CA, KY, MN, MO, NY, PA, WV, UT, and ONT) included the rootstocks G.65, CG.007, CG.11, CG.29, CG.41, CG.179, CG.247, and CG.902 and M.9 EMLA as a standard control. Semidwarf plantings (CA, CO, IA, KY, NY, OR, PA, SD, UT, and WV) included the rootstocks CG.002, CG.13, CG.30, CG.103, CG.202, CG.210, and CG.222 and M.7 EMLA and M.7A as standard controls. Vigorous plantings (CA, KY, NY, OR, UT, and WV) included the rootstocks CG.228, CG.239, CG.253, CG.707, CG.760, and CG.934 and MM.106 and MM.111 as standard controls. Evaluation of growth and production efficiency will be conducted as in other apple rootstock trials.
(i) In 1994, an apple rootstock trial with Gala as the scion cultivar and dwarf rootstocks was planted in a total of 26 locations (AR, CO, GA, IL, IN, IA, ME, MA, MI, NJ, two in NY, NC, OH, OR, two in PA, SC, TN, UT, VT, VA, two in WA, WI, BC, NB, NS, ONT, and Australia). Rootstocks included were M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9 RN29, M.9 Pajam 1, M.9 Pajam 2, B.9, B.491, O.3, V.1, P.2, P.16, Mark, P.22, B.469, M.9 Fleuren 56, V.3, and M.9 NAKBT337). Evaluation of growth and production efficiency will be conducted as in other apple rootstock trials.
(j) In 1994, an apple rootstock trial with Gala as the scion cultivar and semidwarf rootstocks was planted in a total of 26 locations (AR, GA, IL, IN, IA, KY, ME, MI, NJ, NY, NC, OH, OR, PA, SC, TN, UT, VT, VA, two in WA, WI, BC, NB, NS, ONT, and Australia). Rootstocks included P.1, V.2, G.11, CG.13, G.30, and M.26 EMLA. Evaluation of growth and production efficiency will be conducted as in other apple rootstock trials.
(k) In 1994, a peach rootstock trial was established in 22 locations (AR, CO, GA, IL, IN, KS, KY, MD, MS, MI, two in MO, two in NJ, NY, OH, SC, TN, UT, and ONT). Redhaven on Lovell, Bailey, Tennessee Natural 281-1, Nemaguard, Stark's Redleaf, GF.305, Higama, Montclar, Rubira, Ishtara, Myran, S.2729, Chui Lum Tao, Tzim Pee Tao, H7338013, H7338019, BY520-8, Guardian, and Ta Tao 5/Lovell rootstocks were included. Tree size (trunk cross-sectional area, tree height, and canopy spread), time of bloom, yield, yield efficiency, suckering, time of ripening, fruit size, and mortality will be assessed at each site. At four sites (KS, MO, OH, and SC), the effects of these rootstocks on low-temperature tolerance of flower buds will be assessed.
(l) A cherry rootstock trial is scheduled for 1998. It will be planted in CA, CO, MI, NJ, NY, OR, PA, UT, SC, WA, BC, and ONT with a sweet cherry cultivar as the scion and in MI, NY, PA, UT, and ONT with a sour cherry cultivar as the scion. Fifteen rootstocks will be included. Performance will be assessed as in the previous cherry rootstock trial.
(m) An apple rootstock trial is scheduled to be planted in 2000. Possible rootstocks include Bemali, J.9, selections from the Morioka series (Japan), selections from the JE series (Czechoslovakia), selections from the P series (Poland), selections from the Suporter series (Germany), and selections from the G series (Cornell). Members from NY, MA, AR, and NS will lead the project. Performance will be evaluated as in other apple rootstock trials.
Other multi-state/province rootstock trials will be conducted on a regional basis, but will not involve the entire committee in the coordination. However, these will be reported as being under the work of NC-140. Tree performance in the projects will be evaluated as in previously mentioned rootstock trials. These projects include the following:
(a) In 1991, a trial was established at two locations (ME and MA) including Pioneer Mac, Marshall McIntosh, Chic-A-Dee McIntosh, and Rogers Red McIntosh on Mark, M.7 EMLA, M.27 EMLA, and M.26 EMLA rootstocks in all combinations. It will be determined whether or not rootstocks and scion cultivars can interact to affect fruit quality.
(b) In 1994 a pear cultivar/interstem trial was established at three locations (two in OR and WA). Scions included d'Anjou, Bartlett, Bosc, and Comice. All trees had Bartlett seedling as the rootstock, and interstems included d'Anjou, Bartlett, Bosc, Conference, or no interstem.
(c) In 1995, a trial was established at three locations (ME, MA, and NS) including Cortland, McIntosh, Macoun, and Pioneer Mac on B.491, B.146, P.2, P.22, V.1, V.3, B.469, P.16, B.9, M.9, M.9 NAKBT337, and Mark rootstocks in all combinations.
(d) In 1995, a trial was established at three locations (MA, PA, and NB) including Ginger Gold on B.491, P.2, P.22, V.1, V.3, B.469, P.16, B.9, M.9 NAKBT337, and Mark rootstocks.
(e) In 1996, a trial was established at 16 locations across NS, NB, QUE, and ONT including Hartenhof McIntosh and Idared on YP, AR 86-1-25, B.490, and KSC7.
(f) In 1998, a trial will be established at 16 locations (two in CT, four in ME, four in MA, two in NH, RI, and three in VT) including Pioneer Mac on M.9 EMLA, B.9, P.2, and O.3 rootstocks. The intent of this planting is to take the most promising rootstocks of previous NC-140 trials and establish second-level testing at grower orchards.
NC-140 participants will continue individual research to evaluate various aspects of performance and physiology as they related to rootstock and training system: (1) evaluating the performance of various apple rootstocks and interstem combinations (CA, IL, IA, KS, KY, ME, MA, MI, MN, MO, NY, NC, OH, PA, SD, VA, WA, BC, and ONT); (2) evaluating performance of various pear rootstocks and interstem combinations (CA, NY, OR, WA, and ONT); (3) evaluating the performance of various peach rootstocks (CA, GA, IL, and SC); (4) evaluating the performance of various cherry rootstocks (CA, MI, NY, OR, BC, and ONT); (5) assessing winter hardiness as affected by rootstock (IA, KS, MN, MO, OH, BC, NB, and NS); (6) studying the interaction of scion cultivar and rootstock (IA, ME, MA, NY, OH, and OR); (7) determining rootstock effects on fruit quality, maturity, and size distribution (ME, MA, NY, PA, and VA); (8) studying the performance of management and training systems with various species and rootstocks (MO, NY, OH, OR, and WA); (9) measuring the effects of rootstock and various factors on tree physiology (NY and BC); and (10) elemental composition of leaves as it relates to rootstock (OR); (11) evaluating rootstock effects on fruit storability (ME, MA, and OR); and (12) evaluating the economics of various rootstock/scion cultivar combinations (PA).
Objective 2: To assess and improve asexual propagation techniques of pome- and stone-fruit rootstocks.
Laboratory, greenhouse, and field studies will evaluate the propagation characteristics of existing and new rootstocks and develop improved means of asexual propagation for different materials. Studies contributing to this project include: (1) developing improved tissue-culture techniques to propagate apple, pear, and cherry rootstocks (NY, OH, and OR); (2) managing tissue-culture-propagated material after removal from culture (NY); (3) improving softwood and hardwood cutting techniques (GA, NY, and OR); comparing the effects of seedling and asexually propagated peach rootstocks on tree mortality and performance (GA); and (4) overcoming poor rootstock selection in the orchard with inarching (IA and MO).
Objective 3: To improve the ability to identify pome- and stone-fruit rootstocks through morphological, biochemical, and genetic differences.
Various means of rootstock identification will be evaluated during the term of this project. Generally, the rootstocks included under objective 1 will be the focus of these studies, but other rootstocks will be studied as well. Projects will evaluate four means of identification of rootstocks: (1) characterizing morphological differences in rootstock material to enhance identification in stool beds or of liners (PA); (2) utilizing isozyme analysis to identify rootstocks (NY and ONT); (3) adapting randomly amplified polymorphic DNAs to rootstock identification (MA, ME, MI, and NY); and (4) determining the suitability of Fourier transformed infrared spectroscopy as a means of identifying apple rootstocks (CO).
Objective 4. To develop new and better pome- and stone-fruit rootstocks through breeding and genetic engineering, and to acquire new rootstocks from breeding programs in other parts of the world.
To enhance tree performance and pest resistance, traditional breeding programs will pursue improved rootstocks for apples (AR, NY, and NS), pears (OR and WV), and peaches (GA). Further, genetic engineering procedures will be used to enhance pest resistance of apple rootstocks (NY). Many rootstock breeding programs exist worldwide. Significant effort will be made to acquire as much material as possible for future tests (AR, KY, MA, MI, NY, OH, BC, and NS).
Objective 5. To determine biotic and abiotic stress tolerances of pome- and stone-fruit trees in relation to new and existing rootstocks.
Studies will be done to determine stress tolerance of fruit trees as influenced by new and existing rootstocks. Many of these studies will involve rootstocks used in the various trials listed under Objective 1. These include: (1) the cold hardiness of rootstocks and the influence of rootstock on scion cold hardiness for apple (IA, MN, NY, SD, UT, BC, NB, and NS), peach (KS and MO), and cherry (UT); (2) the influence of the interaction of rootstock, scion, interstem, and planting depth on cold hardiness (IA); (3) high-temperature sensitivity of apple roots (PA); (4) effects of root pruning and restriction on tree performance (MD); (5) effects of soil moisture levels on apple tree performance as affected by rootstock (KY and NY); and (6) the influence of rootstock on mineral-stress sensitivity in apple (MI and OH).
Stress tolerance of rootstocks and multiple genetic systems in relation to pathogenic organisms will be investigated including: (1) apple rootstock tolerance of or resistance to fireblight (NY and VA), crown rot (NY and BC), and lesion nematode (NY and ONT); (2) pear rootstock tolerance of or resistance to fireblight (MD and WV); (3) cherry rootstock tolerance of or resistance to Prune Dwarf virus (WA) and Prunus Necrotic Ringspot virus (WA); (4) investigate the use of mulch insulation for reducing the incidence of cytospora canker in peach rootstocks (KS); and (5) root survival following attack by root-feeding nematodes, fungi, or insects in apple (PA) and peach (WV).
DISSEMINATION OF INFORMATION:
At all locations, significant efforts will be made to disseminate the results of both local and NC-140 studies to tree-fruit growers. The Committee will prepare written reports on each trial both five years and ten years after planting. However, particular attention will be given to disseminating results from the project using computer-based INTERNET/World Wide Web technologies. This effort will be led by NJ and VT. The NC-140 WWW 'Home Page' <HTTP://ORCHARD.UVM.EDU/NC140/> will be expanded to include both PUBLIC and PRIVATE information areas. Examples of information to be included in the PUBLIC area are: NC-140 Project objectives, cooperative trial information, project coordinator, and cooperators, rootstock descriptions, and final research results.
The PRIVATE (password-protected) area will be used as an INTRANET to facilitate communication and efficiency in reaching project objectives. Examples of information to be included in the PRIVATE area are: database of project leaders and collaborators, including contact information, interactive discussion forums to facilitate timely communication and collaboration among project members, databases of planted rootstocks, and new candidates for testing, and annual state reports.
This regional Technical Committee will be organized for the North Central Region as outlined in the Manual for Cooperative Regional Research. The executive committee shall consist of the chairperson, vice-chairperson, secretary, immediate past chairperson, and the coordinator of each NC-140 trial. Each year a secretary will be elected to serve for one year, and the past vice-chairperson and the secretary will advance to the next higher office commencing in January. Members of the executive committee will set the annual meeting agenda, write and distribute the minutes and annual report, and act on the Committee's behalf if necessary. An Adminstrative Advisor will act as an advisor to the Committee on procedures and policies related to regional research and provide coordination and communication with other regional projects and the North Central Directors. Annual meetings will be held for the purpose of evaluating current work, planning future work, and coordinating publications of a regional nature which may result from the work undertaken in the regional project.
Project coordinators will be appointed on a continuing basis to coordinate the cooperative rootstock and system trials undertaken in Objective 1: Perry (MI) -- 1987/88 cherry rootstock; Azerenko (OR) -- 1988 pear rootstock; Autio (MA) -- 1990 apple cultivar/rootstock; Marini (VA) -- 1990 apple systems/rootstock; Marini (VA) -- 1990 apple rootstock; Andersen (NY) -- 1990 plum rootstock; Robinson (NY) -- 1992 apple rootstock; Robinson (NY) -- 1993 apple rootstock; Marini (VA) -- 1994 apple rootstock; Reighard (SC) -- 1994 peach rootstock; Kappel (BC) -- 1998 cherry rootstock; Robinson (NY) -- 2000 apple rootstock. These coordinators will provide technical oversight concerning those plantings, maintain contact with the participants through correspondence, transmit pertinent information to participants and the Committee to insure uniformity of the studies, prepare data collection forms and details of coordinated procedures which will permit a consolidation of the research findings, assemble and analyze combined data or summarize data previously analyzed, initiate all publications regarding the planting, and report annually to the Committee on progress of the planting.
Anderson, P.C., P.B. Lombard, and M.N. Westwood. 1984. Leaf conductance, growth and survival of willow and deciduous fruit trees under flooded soil conditions. J. Amer. Soc. Hort. Sci. 109:132-138
Autio, W. R., J. A. Barden, and G. R. Brown. 1991. Rootstock affects ripening, size, mineral composition, and storability of 'Starkspur Supreme Delicious' in the 1980-81 cooperative planting. Fruit Var. J. 45:247-251.
Autio, W.R., R.A. Hayden, W.C. Micke, and G.R. Brown. 1996. Rootstock affects ripening, color, and shape of 'Starkspur Supreme Delicious'. Fruit Var. J. 50:41-45.
Barritt, B.H., M.A. Dilley, and B.J. Schonberg, 1990. Potential new apple rootstock producing trees similar to M.9 in size. Compact Fruit Tree 23:4-7
Barritt, B.H., B.S. Konishi, and M.A. Dilley. 1995. Performance of three apple cultivars with 23 dwarfing rootstocks during 8 seasons in Washington. Fruit Var. J. 49:158-170.
Beckman, T., W.R. Okie, and A.P. Nyczepir. 1996. The USDA-ARS stone fruit rootstock development program at Byron, GA. Acta Hort. (In press).
Conrod, J.D. , D.J. Larson, and E.E. Hoover. 1996. Rootstock effects terminal bud set in 'Starkspur Supreme Delicious' apples. Fruit Var. J. 50:43-44.
Cummins, J.N. and H.S. Aldwinkle. 1982. New and forthcoming apple rootstocks. Fruit Var. J. 36:66-73.
Egilla, J.N. and D.H. Byrne, 1989. The search for peach rootstocks tolerant to alkalinity. Fruit Var. J. 43:7-11.
Embree, C.B. 1995. A photographic description of fruit of certain apple rootstocks. Fruit Var. J. 49:59-64.
Fernandez, R.T., R.L. Perry, and D.C. Ferree. 1995. Root distribution patterns of nine apple rootstocks in contrasting soil types. J. Amer. Soc. Hort. Sci. 120:6-13.
Ferree, D.C., 1983. Cooperative rootstock research of the NC-140 and IDFTA in the US and Canada. Compact Fruit Tree 16:103.
Ferree, D.C., R.C. Funt, and C.K. Chandler, 1988. Comparison of early performance and fireblight susceptibility of 12 early season apple cultivars. Fruit Var. J. 42:24-28.
Fisher, M. 1996. The Pillnitz apple roostock breeding program. Acta Hort. (in press).
Foolad, M.R., S. Arulsekar, V. Becerra, and F.A. Bliss. 1995. A genetic map of Prunus based on an interspecific cross between peach and almond. Theor. Appl. Genet. 91:262-269.
Garner, R.J. 1946. The recognition of some apple and plum rootstocks in the nursery. Rpt. E. Malling Res. Sta. For 1945: 130.
Gheyas, F., E. Young, S.M. Blankenship, and R.F. McFeeters. 1996. Dietary Fiber composition of 'Starkspur Supreme Delicious' apple fruit as influenced by rootstock and growing region. Fruit Var. J. 50:35-41
Hirst, P.M. and D.C. Ferree, 1996. Effects of rootstock on bud development and flower formation of 'Starkspur Supreme Delicious' apple. Fruit Var. J. 50:24-34.
Howard, B.H. 1987. Propagation. pp. 29-77. In: R.C. Rom and R.F. Carlson (eds). Rootstocks for Fruit Crops. John Wiley & Sons, NY.
Huang, F.H., S. Tsai, and R.C. Rom, 1983. An electrophoresis method for water soluble protein of Prunus. HortScience 19:242-243.
Lang, G., W. Howell, D. Ophardt, and G. Mink. 1996. Biotic and abiotic stress responses of interspecific hybrid cherry rootstocks. Acta Hort. (in press).
Larson, K.D., T.M. DeJong, and R.S. Johnson. 1988. Physiological and growth responses of mature peach trees to postharvest water stress. J. Amer. Soc. Hort. Sci. 113:296-300.
Melakeberhan, H., G.W. Bird, and R.L. Perry. 1994. Plant parasitic nematodes associated with cherry rootstocks in Michigan. J. Nematology 26:767-772.
Menendez, R.A., F.E. Larsen, and R. Fritss. 1986. Identification of apple roostock cultivars by isozyme analysis. J. Amer. Soc. Hort. Sci. 111:933-937.
Mircetich, J.S.M and G.T. Browne, 1989. Phytophthora root and crown rot of deciduous fruit trees: The influence of different rootstocks and soil moisture conditions on severity of the disease. Compact Fruit Tree 22:115-125.
Morin, R., C. Hamel, J.A. Fortin, R.L. Granger, and D.L. Smith. 1994. Apple rootstock response to vesicular-arbuscular mycorrhizal fungi in a high phosphorous soil. J. Amer. Soc. Hort. Sci. 119:578-783.
NC-140. 1991a. Performance of 'Starkspur Supreme Delicious' apples on 9 rootstock over 10 years in the NC-140 cooperative planting. Fruit Var. J. 45:192-199.
NC-140. 1991b. Performance of 'Starkspur Supreme Delicious' apples on 9 rootstock at 27 sites over 10 years. Fruit Var. J. 45:200-208.
NC-140. 1991c. Abnormalities in 'Starkspur Supreme Delicious' on 9 rootstocks in the 1980-81 NC-140 cooperative planting. Fruit Var. J. 45:213-219.
NC-140. 1996a. Performance of the NC-140 Cooperative Apple Rootstock Planting: I. Survival, tree size, yield and fruit size. Fruit Var. J. 50:6-11.
NC-140. 1996b. Performance of the NC-140 Cooperative Apple Rootstock Planting: II. A 10-year summary of TCA, yield and yield efficiency at 31 sites. Fruit Var. J. 50:11-17.
NC-140. 1996c. Horticultural characteristics of 'Starkspur Supreme Delicious' apple on 15 rootstocks at 24 sites. Fruit Var. J. 50:18-24.
Olien, W.C. and A.N. Lakso, 1986. Effect of rootstock of apple (Malus domestica) tree water relations. Physiol. Plant. 67:421-429.
Perry, R. L. 1987. Cherry rootstocks. pp. 217-264. In: R.C. Rom and R. F. Carlson (eds). Rootstocks for Fruit Crops. John Whiley & Sons, NY.
Perry, R.L., G. Lang, R. Andersen, L. Anderson, A. Azarenko, T. Facteau, D. Ferree, A. Gaus, F. Kappel, F. Morrison, C. Rom, T. Roper, S. Southwick, G. Tehrani, and C. Walsh. 1996. Performance of the cherry rootstock trials in North America. Compact Fruit Tree 29:37-58.
Quamme, H.A. and R.T. Brownlee, 1993. Early performance of micropropagated trees of several Malus and Prunus cultivars on their own roots. Can. J. Plant Sci. 73:847-855.
Reilly, C.C., C.R. Gentry, and J.R. McVay. 1987. Biochemical evidence for resistance of rootstocks to peachtree borer and species separation of peachtree borer and lesser peachtree borer (Lipdoptera: Sesiidae) on peach trees. J. Econ. Ent. 80:338-343.
Rom, C.R. 1995. Apple shoot and trunk growth as affected by rootstock. HortScience 30:770.
Rom, C.R., R.C. Rom, W. R. Autio, D.C. Elfving, and R.A. Cline. 1991. Foliar nutrient content of 'Starkspur Supreme Delicious' on nine rootstock. Fruit Var. J. 45:252-263.
Rom, R.C. 1980. Problems associated with interstem apple trees. Proc. AR State Hort Soc.: 40-43.
Rom, R.C. 1988 Rootstock breeding and evaluation. Proc. XXII Int. Hort.Cong. 23:97-118.
Simon, C.J., and N.F. Weeden. 1992. Molecular analysis and cloniong of ribosomal DNA. J. Amer. Soc. Hort. Sci. 117:164-168.
Simons, R.K. 1984. Selecting rootstocks for Illinois apple orchards. Trans. IL State Hort. Soc. 118:47-51.
Simons, R., R.A. Hayden, P. Domoto, F. Morrison, W. Lord, R. Perry, M. Warmund, D.C. Ferree, and E. Stang. 1986. NC-140 1976 cooperative interstem plantings. Fruit Var. J. 40:108-115.
Stong, D. And A. Azarenko. 1991. Dry matter partitioning in 'Starkspur Supreme Delicious' on nine rootstocks. Fruit Var. J. 45:238-241.
Therios, I.N. and N.D. Misopolinos. 1989. Differences in tolerance to sodium chloride salinity between three commercial apple rootstocks. Soilless Culture 5:55-71.
Warmund, M.R., W.R. Autio, J.A. Barden, J.N. Cummins, P.A. Domoto, C.G. Embree, R.L. Granger, F.D. Morrison, J.R. Schupp, and E. Young. 1996. Blackheart injury in 'Starkspur Supreme' Delicious on 15 rootstocks in the 1984 NC-140 Cooperative Planting. Fruit Var. J. 50:55-62.
Warmund, M. R. and B.H. Barritt. 1994. Survival and growth of 'Empire' apple trees chip budded onto Mark and M.9 rootstock. Fruit Var. J. 48:245-250.
Warmund, M.R., B.H. Barritt, J.M. Brown, K.L. Schaffer, and B.R. Jeong. 1993. Detection of vascular discontinuity in bud unions of 'Jonagold' apple on Mark rootstock with magnetic resonance imaging. J. Amer. Soc. Hort. Sci. 118:92-96.
Warmund, M.R., D.C. Ferree, P. Domoto, J.A. Barden, C.A. Mullins, and R.L. Granger. 1991. Blackheart injury in 'Starkspur Supreme Delicious' on 9 rootstocks in the 1980-91 NC-140 Cooperative Planting. Fruit Var. J. 45:219-223.
Webster, A.D. 1996. A review of roostock research and development and future opportunities. Acta Hort. (in press).
Webster, A.D. and K. Tobutt. 1994. European and East Malling rootstock research -- new and promising apple rootstocks. Compact Fruit Tree 27:17-24.
Welander, M. 1988. Plant regeneration from leaf and stem segments of shoots raised in vitro from mature apple trees. J. Plant Physiol. 132:738-744
Wicks, T.J. 1989. Susceptibility of almond and cherry rootstocks and scions to Phytophthora species. Australian J. Exp. Agr. 29:103-109
Project Leaders and Cooperators:
Name, State, Institution, Specialization
Curt R. Rom*, AR, Arkansas Agric. Exp. Sta., Pomology
Scott Johnson*, CA, California Agric. Exp. Sta., Pomology
Stephen Southwick, CA, California Agric. Exp. Sta., Pomology
Ted DeJong, CA, California Agric. Exp. Sta., Pomology
Alvan Gaus*, CO, Colorado Agric. Exp. Sta. & Coop. Ext., Pomology
Harold J. Larsen, CO, Colorado Agric. Exp. Sta. & Coop. Ext., Plant Pathology
Tom Beckman, GA, USDA-ARS, Byron, Pomology
Mosbah M. Kushad*, IL, Illinois Agric. Exp. Sta., Pomology
Peter Hirst*, IN, Purdue Univ. Agric. Exp. Sta., Pomology
Paul A. Domoto*, IA, Iowa Agric. Exp. Sta., Pomology
Frank Morrison*, KS, Kansas Agric. Exp. Sta., Pomology
Alan Erb, KS, Kansas Agric. Exp. Sta., Pomology
Gerald R. Brown*, KY, Kentucky Agric. Exp. Sta., Pomology
John Strang, KY, Kentucky Agric. Exp. Sta., Pomology
Dwight Wolfe, KY, Kentucky Agric. Exp. Sta., Pomology
James R. Schupp*, ME, Maine Agric. Exp. Sta., Pomology
Christopher S. Walsh*, MD, Maryland Agric. Exp. Sta., Pomology
Wesley R. Autio*, MA, Massachusetts Agric. Exp. Sta., Pomology
Duane W. Greene, MA, Massachusetts Agric. Exp. Sta., Pomology
Daniel R. Cooley, MA, Massachusetts Agric. Exp. Sta., Plant Pathology
Ronald L. Perry*, MI, Michigan Agric. Exp. Sta., Pomology
Any Iezzoni, MI, Michigan Agric. Exp. Sta., Pomology
James Flore, MI, Michigan Agric. Exp. Sta., Pomology
James Nugent, MI, Michigan Agric. Exp. Sta., Pomology
Scott Swinton, MI, Michigan Agric. Exp. Sta. Agric., Economics
Alan Jones, MI, Michigan Agric. Exp. Sta., Plant Pathology
William Shane, MI, Michigan State Univ. Extension, Pomology
Philip Schwallier, MI, Michigan State Univ. Extension, Pomology
Emily E. Hoover*, MN, Minnesota Agric. Exp. Sta., Pomology
Michele Warmund*, MO, Missouri Agric. Exp. Sta., Pomology
Patrick Byers, MO, Southwest Missouri State Univ., Pomology
Martin Kaps, MO, Southwest Missouri State Univ., Pomology
Winfred P. Cowgill, Jr.*, NJ, New Jersey Agric. Exp. Sta., Pomology
Terence Robinson*, NY, New York Agric. Exp. Sta., Pomology
Robert L. Andersen, NY, New York Agric. Exp. Sta., Pomology
Herb Aldwinckle, NY, New York Agric. Exp. Sta., Plant Pathology
James Cummins, NY, New York Agric. Exp. Sta., Pomology
Norman F. Weeden, NY, New York Agric. Exp. Sta., Genetics
Stephen A. Hoying, NY, New York Agric. Exp. Sta., Pomology
Michael Parker*, NC, North Carolina Agric. Exp. Sta., Pomology
Turner Sutton, NC, North Carolina Agric. Exp. Sta., Plant Pathology
Richard Unrath, NC, North Carolina Agric. Exp. Sta., Pomology
David C. Ferree*, OH, Ohio State Agric. Exp. Sta., Pomology
Diane Miller, OH, Ohio State Agric. Exp. Sta., Pomology
Eugene Mielke*, OR, Oregon State Agric. Exp. Sta., Pomology
Tim Facteau, OR, Oregon State Agric. Exp. Sta., Pomology
Anita Azarenko, OR, Oregon State Agric. Exp. Sta., Pomology
George M. Greene*, PA, Pennsylvania Agric. Exp. Sta., Pomology
Robert M. Crassweller, PA, Pennsylvania Agric. Exp. Sta., Pomology
David M. Eissenstat, PA, Pennsylvania Agric. Exp. Sta., Root Physiology
James Travis, PA, Pennsylvania Agric. Exp. Sta., Plant Pathology
John Halbrendt, PA, Pennsylvania Agric. Exp. Sta., Nematology
Jay Hooper, PA, Pennsylvania Agric. Exp. Sta., Agric. Economics
Loren D. Tukey, PA, Pennsylvania Agric. Exp. Sta., Pomology
Gregory L. Reighard*, SC, South Carolina Agric. Exp. Sta., Pomology
Anne Fennell*, SD, South Dakota Agric. Exp. Sta., Pomology
Charles A. Mullins*, TN, Tennessee Agric. Exp. Sta., Pomology
Dennis Deyton, TN, Tennessee Agric. Exp. Sta., Pomology
J. LaMar Anderson*, UT, Utah Agric. Exp. Sta., Pomology
Donald V. Sisson, UT, Utah Agric. Exp. Sta., Statistics
Sherman V. Thompson, UT, Utah Agric. Exp. Sta., Plant Pathology
John A. Barden*, VA, Virginia Agric. Exp. Sta., Pomology
Richard P. Marini, VA, Virginia Agric. Exp. Sta., Pomology
Marvin Lentner, VA, Virginia Polytech. Inst. & State Univ., Statistics
Douglas Pfieffer, VA, Virginia Agric. Exp. Sta., Entomology
Lorraine Berkett, VT, Vermont Agric. Exp. Sta., Int. Pest Man.
Jon Clements, VT, Vermont Agric. Exp. Sta., Pomology
Bruce H. Barritt*, WA, WSU Agric. Res. Center, Pomology
Greg Lang, WA, WSU Agric. Res. Center, Pomology
Teryl Roper*, WI, Wisconsin Agric. Exp. Sta., Pomology
Richard Bell, WV, USDA-ARS, Kearneysville, Pomology
Bill Thompson, Australia, Institute of Plant Sci., Victoria, Pomology
Frank Kappel, BC, Agriculture Canada, Summerland, Pomology
H. A. Quamme, BC, Agriculture Canada, Summerland, Pomology
Jean-Pierre Privé, NB, Agriculture Canada, Bouctouche, Pomology
Charlie Embree, NS, Agriculture Canada, Kentville, Pomology
John Cline, ONT, Hort. Res. Inst., Simcoe, Pomology
Neil W. Miles, ONT, Hort. Res. Inst., Vineland, Pomology
William Lay, ONT, Hort. Res. Inst., Vineland, Plant Breeding
Gordon Bon, ONT, Agriculture Canada, Harrow, Plant Pathology
John Porter, ONT, Agriculture Canada, Vineland, Nematology
Raymond L. Granger, QUE, Agriculture Canada, St. Jean, Pomology
Administrative Advisor: Ian Gray MI Michigan Agric. Exp. Sta.
Summary of Work Accomplishments:
Over the current duration of this project, the NC-140 technical committee vigorously continued to evaluate and study fruit tree rootstocks on a national scale. Important highlights of accomplishments are:
The completion of one massive cooperative multi-state comparison of apple rootstocks planted in 1984 and the publication of 10 refereed papers summarizing the results;
The continuation of five other cooperative plantings made in 1990 and the publication of four interim reports summarizing the initial results;
The establishment of four additional cooperative plantings in 1992, 1993, and 1994;
The development of plans for the establishment of two additional plantings in the next five years;
The evaluation of more than 80 rootstock genotypes for commercial potential in all major fruit growing regions of the US and Canada;
The annual sharing of detailed state reports at the technical committee meeting;
The involvement of basic scientists to produce new rootstocks (biotechnologist to genetically engineer apple rootstocks for fireblight resistance) and study rootstock physiology and genetics;
The extension of results by cooperating members to fruit growers in cooperating states (over the period 1992-1996, cooperators gave more than 470 presentations to growers groups, held 170 field days in NC-140 plots, and had more than 70,000 grower contacts);
The publication of over 150 grower-oriented publications and 58 refereed journal articles on rootstocks during the project's duration by committee members;
The establishment of an e-mail discussion group 'list-serv' for project members in 1996 (the closed e-mail discussion group, <ROOTST-L@UAFSYSB.UARK.EDU>, has been used frequently by project members during 1996 to communicate, prepare joint publications, and plan for the annual technical committee meetings);
The establishment of an NC-140 Internet/World Wide Web (WWW) Home Page in 1996 (the WWW 'Home Page', <HTTP://ORCHARD.UVM.EDU/NC140/> is being developed and used to assist in disseminating NC-140 Project research-generated information to commercial tree fruit growers and nurserymen throughout the world); and
Individual committee members leveraged $1.1 million dollars in grant funds from grower groups from 1992-1996 to support NC-140 related research (this money allowed them to conduct the uniform trials and to carry on a wide variety of individual experiments on apple rootstocks, ranging from breeding new rootstocks to local evaluation of commercial rootstocks).
Impact of Accomplishments:
The impact of the accomplishments of this project on the commercial fruit industry and society at large is significant. In some cases, promising rootstocks have moved ahead while in other cases concerns were raised which resulted in the discontinuation of particular rootstocks. In still other cases, NC-140 data resulted in a slowing down of commercial adoption. Results from this project have saved the industry millions of dollars in costs from poor rootstocks and have helped earn millions of dollars from more productive and adapted rootstocks and training systems as the industry has moved to new cultivars. Helping the fruit industry stay competitive and healthy has benefitted society at large by providing a safe and inexpensive fruit supply and by improving the economy of rural America. Specific impacts were:
The demonstration of which climatic areas are suitable for M.9 apple rootstock and where the risk of fireblight is too severe for its use;
The identification of B.9 as a superior dwarfing apple rootstock with widespread adaptability and superior performance in northern fruit growing areas resulting in its large-scale commercial propagation and sale by several nurseries;
The identification of Bailey peach rootstock as a superior rootstock for northern fruit-growing areas resulting in an expansion of its commercial propagation and sale by several nurseries;
The development and identification of Guardian as superior peach rootstock with resistance to peach tree short life by SC and GA (this has resulted in immediate adoption and tremendous demand for this rootstock by nurseries and growers in the southeastern United States);
The identification of virus susceptibility of several Gisela cherry rootstocks and the subsequent slowing down of commercialization of these stocks until more data are acquired;
The prevention of commercialization of the GM cherry rootstocks due to poor performance;
The discontinuation of Mark apple rootstock due to serious declines in tree vigor induced by soil line swelling as the trees aged; and
Information from these studies has assisted nurserymen in propagation technology and in deciding whether or not to utilize micropropagation in commercializing new rootstocks.
The final results of the 1984 apple rootstock project, which was planted in 31 states and compared 15 rootstocks, were summarized and published in 10 papers in the Fruit Varieties Journal 50 (1), 1996. Major points from those papers are: Tree loss was greatest on P.22 (32%) and MAC.39 (21%). Trees on P.18, A.313, B.490, MAC.1, and M.4 had trunk cross-sectional areas and yield efficiencies similar to seedling. P.1 produced trees similar in size, production, and yield efficiency to M.7 EMLA. C.6 and M.26 EMLA resulted in trees of similar size, yield, and yield efficiency. MAC.39 and B.9 had similar trunk cross-sectional area, yield, and yield efficiency, but trees on B.9 were shorter with smaller spread. Fruit size over six years from trees on P.22, M.4, and seedling was small, while fruit size tended to be large from trees on P.18, A.313, and C6. Practical recommendations to the fruit industry are that P.1 could be an alternative rootstock for M.7 in regions where lack of winter hardiness is a concern. In the M.26-tree-size class, there was no clear advantage to suggesting alternatives to M.26. In the M.9-tree-size class, B.9 should be considered where M.9 has not been sufficiently hardy. Tree losses were highest in six Midwestern sites, exceeding 20%. B.9 had the best survival of the dwarfing rootstocks in this study. Sites in KS, GA, IL, CA, VA, MO, NC, and MI had trees with 39 to 16% larger-than-average trunk cross-sectional area, while trees in TN, PA, and Mex were 40% smaller than the average of all sites. Averaged across rootstocks, sites with the greatest yield efficiency were MA, CA, OH, and BC and those with lowest efficiency were KS, TN, MN, NY, AR, and NC.
At the conclusion of the experiment, various tree factors were rated along with the potential for each stock at each site. Although, in general, results were consistent across sites, there was considerable variation across sites with some factors. In some cases, sites were at opposite extremes in their ratings which indicates that the rootstock choice will continue to be very site specific.
Other results from subsets of all the sites were numerous and included the following. The timing of flower formation varied from year to year, but was not affected by rootstock. Fruit ripening was correlated with tree vigor, with the most dwarfing rootstocks resulting in the earliest ripening. The consistent early ripening fruit were from trees on B.9 and P.16 and the most consistently late ripening fruit from trees on M.4, P.18, and seedling. Black-heart winter injury was greatest in IA, KS, MO, and QUE, while injury was least in MA, NC, NS, NY, and VA. Overall, trees on B.9, P.2, P.16, and P.22 were more susceptible to black-heart injury than those on B.490, MAC.1, C.6, and MAC.39. Stability of rootstock performance across sites was inversely related to mean yield performance, indicating that among the higher performing dwarfing rootstocks, performance will be variable depending on the site. This result requires local testing of dwarfing rootstocks to ensure their local adaptability. Such testing is the goal of the NC-140 committee and these results support the validity and need for this project and the approach taken by the technical committee.
The two uniform trials established in 1990 (interaction of cultivar and rootstock and interaction of system and rootstock) have completed 5 years. An interim report has been published on the cultivar/rootstock trial (Fruit Varieties Journal 50:175-187) and two are in press for the system/rootstock trial. Preliminary results from the cultivar-by-rootstock study show that M.26 EMLA, B.9, and Mark were consistent in their performance across scion cultivars. M.26 EMLA resulted in a large tree with low precocity, high yields, low yield efficiency and large fruit size while B.9 produced a small tree, with low yields, high yield efficiency, and large fruit. Mark produced a small tree with high precocity, low yields, high yield efficiency, and small fruit. M.9 EMLA and O.3 were variable in their results across scion cultivars. With Golden Delicious, Empire, and Rome, O.3 produced a large tree, with low precocity, high yields, moderate yield efficiency, and small fruit. With Jonagold, O.3 resulted in a moderately sized tree, with moderate yield. With Jonagold, Empire, and Rome, M.9 EMLA resulted in a moderately sized tree, with low precocity, high yield, moderate yield efficiency, and large fruit. With Golden Delicious, M.9 EMLA resulted in low yields and low yield efficiency. From these results B.9 appears to be the most promising rootstock.
Preliminary results from the system-by-rootstock interaction study showed that there were significant system-by-rootstock-by-site interactions. The vertical axis (VA)/P.1, VA/M.26, and central leader/M.26 had the largest trunk cross-sectional area and canopy volume while the slender spindle system had the smallest canopy volume. The systems with lowest tree densities had the lowest cumulative yields at almost all sites, while treatments with the highest tree densities had the highest yields. Lowest yield efficiency occurred for treatments with P.1 and M.26 rootstocks, and the highest yield efficiency occurred with VA/M.9, VA/O.3, and VA/Mark with each cultivar and at most sites. In the guard rows of the systems trial, another rootstock study was conducted. Preliminary results from this study showed that at all sites, P.1 had the largest trunk cross-sectional area and M.27 the smallest. At most sites, M.9, MAC.39, Mark, B.9, and O.3 were similar. At most sites Mark, O.3, and B.9 had the highest yields and M.27 and P.1 the lowest. Yield efficiency at all locations was lowest for P.1 and M.26, and there was little difference among the other rootstocks.
The trials established in 1992 and 1993 are comparisons of new rootstocks from the Geneva breeding program of Drs. Cummins and Aldwinckle. They were planted over two seasons, with 13 sites in 1992 and 11 sites in 1993. It is too early for conclusions from these trials, but an interim report is planned for 1997. The trial established in 1994 is a comparison of 18 dwarfing rootstocks and 6 semidwarfing rootstocks, including several rootstocks which showed promise in preliminary trials by individual cooperators. Preliminary results should be available in 1999.
Many additional results have been reported from studies by individual cooperators during this project's current duration. Considerable work was reported on Mark rootstock. The work showed that Mark produces soil line swelling of undifferentiated tissue, which leads to a debilitating effect on the tree. This response results in extreme drought sensitivity and small fruit size. These problems have lead to abandonment of this rootstock in the commercial industry. Other areas receiving considerable work are winter hardiness, drought tolerance, and fireblight of rootstocks. Several new rootstocks have been released in the U.S. and around the world. The NC-140 Committee is attempting to evaluate these as quickly as possible.
The first NC-140 cooperative pear rootstock trial was established at 16 sites in 1988. Over the current duration of this project, the NC-140 technical committee continued to evaluate this planting. A final report is planned for 1999. Preliminary results have shown than OHXF.40 has the best cumulative yield and the highest yield efficiency. Pyrus calleryana seedlings also have shown promise.
Individual committee members have conducted considerable additional research on pear rootstocks. Results show that OHXF.87 shows considerable promise, giving high cumulative yield. In many of these trials, OHXF.40 also has been one of the best performing rootstocks. Neither of these rootstocks is dwarfing. Results from pear training-system research showed that the central palmette system had greater cumulative yield than either central leader or slender spindle systems. The central leader system was the least productive.
The completion of the initial peach trial in 1991 was followed in 1994 with a second trial located at 22 sites. Results from the initial trial assisted in reducing the number of standard rootstocks, and it identified promising candidates needing a second test. Plum rootstocks and hybrid peach X plum rootstocks generally had low survival and performances in the initial trial. Bailey rootstock was identified as a superior rootstock for states and provinces in the north, with the highest tree survival and longevity rating. As a result of this trial, a large commercial nursery in Michigan (Hilltop) now offers 75 per cent of their commercial line of peach trees on this rootstock. Poor results with the hybrid and plum rootstocks, inhibited these candidates from gaining commercial acceptance and availability in North America.
A new peach rootstock, tolerant of peach tree short life decline, developed in the southeastern United States was released by those cooperators and included in the 1994 trial.
In the 1987 sweet- and tart-cherry trial, several of the rootstock candidates demonstrated very promising potential of dwarfing and produce large, early crops of sweet cherries. The North American producers became very excited as a result of early cooperator reports in various mediums and presentation venues. Some of the more precocious and dwarfing rootstocks in the first five years began to decline in production and health in the second five years. Cooperators became concerned and provided budwood to assess the potential association with virus infection, which proved negative. A very comprehensive terminal report was presented to the International Dwarf Fruit Tree Association at their 1996 annual meeting and published in their conference proceedings. As a result of this trial, MXM 2 was confirmed as a commercial rootstock for standard-size trees in the Great Lakes region for sweet cherry. The Gembloux rootstocks performed poorly across North America and reduced their commercial potential and availability. Results from the sweet-cherry trial indicated that subsequent field testing of the Gisela rootstocks should be accompanied by a management plan to include strategic renewal pruning to avoid stunting and runting on these precocious rootstocks. These strategies also will be incorporated in the 1998 trial. For Montmorency tart cherry, none of the candidates tested, appeared to be superior to Mahaleb seedling, the standard rootstock.
Promising candidates from the initial trial have been included among untested ones in the planning of a new trial that is scheduled for establishment in 16 locations in 1998. Planning and preparation of the 1998 trial began in 1994 meetings.
The 1990 plum rootstock trial continues to produce brief progress reports. A new coordinator will be assigned in 1996, following the passing of its coordinator G. Tehrani (ONT).
Degree of Objective Accomplishment:
Objective 1. To evaluate rootstock and multiple genetic systems in different environments.
To a large extent this objective continues to be met by the project. Evidence of this is:
The completion of the 1984 cooperative apple planting and the coordinated publication of 10 research papers in Fruit Varieties Journal on the results;
The publication of interim reports on the 1987 cherry rootstock trial in Compact Fruit Tree, the 1990 cultivar/rootstock trial in Fruit Varieties Journal, and two papers on the 1990 system/rootstock trial in Acta Hort;
The continued planning and implementation of new trials resulting in the 1992/1993 apple trials, the 1994 apple and 1994 peach trials, and future plans for a 1998 cherry rootstock trial and a 2000 apple rootstock trial with the most promising rootstocks from the Geneva breeding program and new rootstocks from Europe and Japan;
The formation of new subcommittees at the 1995 technical committee meeting to work on a future plantings of apple, cherry, pear, and plum/peach trials with a host of new rootstocks from Europe and South Africa;
The formation of a new subcommittee to work on importation and quarantine problems associated with bringing new rootstocks into the United States;
The extension of research results from this project to growers and nurserymen as evidenced by some 470 oral presentations at grower meetings and 150 publications aimed at growers;
The multi-state/province trials with both apple peach and cherry have shown significant interaction of rootstock, site, and cultivar, leading to different conclusions for different locations across North America, illustrating the necessity of the coordinated trial approach that this committee has taken to test rootstocks nationwide; and
This results of the field trials have significantly impacted the fruit industry in North America [in some cases, promising rootstocks have moved ahead (e.g., B.9 for apples and Bailey for peaches), in other cases, concerns were raised which resulted in the discontinuation of particular rootstocks (e.g., Mark for apple and the GM rootstocks for cherry), and in other cases, concerns resulted in a slowing down of commercial adoption (e.g., several Gisela cherry rootstocks, while promising, elicited concerns about rootstock/scion compatibility which emphasized the need to be cautious in commercial recommendations and for the need for both long-term and widespread testing)].
Objective 2. To evaluate the performance of various rootstock/scion combinations under different management systems.
This objective has been addressed successfully for apple but not sufficiently for other fruits. With apple, we have addressed this objective by organizing and conducting the 1990 rootstock/system trial. In addition, several cooperators are conducting separate research on orchard systems and rootstock interactions which contribute to this objective. In
general, results have indicated that with the more dwarfing rootstocks, a support system is important or essential for optimum performance. We also have observed that training systems that involve pruning in the early years reduce tree performance. These observations have led to the modification of testing protocols under Objective 1 to include support systems for dwarfing rootstock trials and minimal pruning strategies.
For stone fruits and pears, no uniform trials were established; however, independent trials were established by NC-140 members in OR and WA. Information and progress reports have been shared with the committee in annual meetings. In Utah, an independent study was begun on the effects of ground-cover management on the performance of tart cherries.
Objective 3. To develop improved means of asexual propagation of pome and stone fruit rootstocks.
Work under this objective has been conducted by individual cooperators yet good progress has been made in several key areas:
The improvement of conventional propagation of hard-to-root clones of apple (NY), cherry (BC, NY, and OR), and peach (BC and GA);
Biochemical methods of rootstock identification, (MA, ME, and NY); and
Micropropagation of rootstocks and micropropagation carryover effects on orchard performance (NY).
Information from these studies has assisted nurserymen in propagation technology and in deciding whether to utilize micropropagation in commercializing new rootstocks.
Objective 4. To determine biotic and abiotic stress tolerance of fruit trees in relation to new and existing rootstocks and multiple genetic systems.
Work under this objective has made good progress toward understanding the stress tolerance of various rootstock clones and how to manage stresses of rootstocks. The work is being done by individual cooperators and is often not coordinated by the committee, but results are shared at the annual meeting. With many studies, experiments are done using the uniform trials set up under Objective 1. Studies have included:
Evaluation of timing of winter freezes on rootstock cold tolerance of rootstocks and their effect on scions (IA, KY, MN MO, BC, and NB);
Evaluation of water stress tolerance of dwarfing rootstocks (MI and NY);
Evaluation of water penetration and utilization rates among rootstocks (MI);
Breeding new rootstocks for cold hardiness and fireblight and crown rot resistance (AR, NY, and NS);
Testing rootstocks for vole resistance (NY);
Studies on the virus sensitivity of apple and cherry rootstocks (CA, NY, and WA) (several of the new Gisela rootstocks were found to be highly sensitive, and independent studies are being conducted on effects of cherry rootstock on cherry stem pitting, prune dwarf, and prunus necrotic ring spot viruses);
Evaluation of fireblight susceptibility of apple cultivars and rootstocks (OH, NY, and WA);
Evaluation of apple rootstocks for tolerance to apple replant disorder (NY);
Evaluation of phenolic and tannin content of apple rootstocks (PA);
Screening of peach rootstocks to reduce or suppress the effects of peach tree short life in the southeastern United States [a new rootstock, BY520-9 (Guardian), was identified, developed, and released that demonstrated increased longevity in peach-tree-short-life sites (GA and SC)];
Studies on the effects of rootstock on peach tree suckering, bacterial canker, and short life (SC);
Studies on the effects of cytospora and rootstock on sweet and tart cherry tree survival (UT); and
Research on rootstock effects on bacterial canker of cherry (CA);
Objective 5. To develop expert systems which will identify key research needs and improve the decision-making process regarding choice of rootstock, scion and management system.
Work on computer expert systems, including decision-making assistance for rootstock selection and orchard spacing is continuing at two locations (OH and PA). Results are shared at
the annual meeting. The committee has not met this objective fully, and work is proceeding.
Areas Needing Further Investigation:
1) Uniform rootstock evaluation trials of new promising rootstocks. A number of new apple, pear, peach, plum, and cherry rootstocks are now becoming available. A number of these are being commercialized without being tested adequately. A pressing need for the North American fruit industry is to get unbiased performance data as soon as possible. The most efficient and economical way to get this information is through the coordinated trials of NC-140 which are universally accepted and respected. Barriers to accomplishing this are the lack of suitable plant material. In some cases, virus-free plant material is not available and will require first passing the material through quarantine. One of NC-140's primary concerns is the need to develop protocols that will help expedite the importation and multiplication of rootstock candidates for trials and independent study projects. The newly formed germplasm acquisition committee of NC-140 will help to speed the process of getting new rootstocks into trials.
2) Systems trials with promising rootstocks in a limited number of sites. The initial apple systems trial has shown that rootstock performance can be affected by training system. The latest sweet-cherry rootstock trial demonstrated the need to evaluate the performance of promising rootstocks under differing management systems in a uniform cooperative trial.
3) Develop new rootstocks through both traditional sexual breeding and through genetic engineering. A number of important problems with rootstocks have not been addressed through breeding. A proposal has been supported by the NC-140 committee to have the USDA take over the national apple breeding program at Geneva which would assure a continued stream of new apple rootstocks for the NC-140 testing program.
4) Improve the propagation of rootstocks. Many of the new rootstocks for apple and pear are difficult to propagate, and if improved methods are not developed, their adoption by the nursery industry will be resisted. More work is needed in developing methods for the biochemical identification or confirmation of the identity of stone-fruit rootstock candidates.
5). Understand environmental and biotic stress tolerances of existing and new rootstocks. Important areas include low temperature, orchard replant disease, fireblight, collar rot, union necrosis, and soil adaptability. Research efforts to understand stress tolerance will lead to management strategies and also to breeding strategies. Further work is needed in the area of virus sensitivity and its impact on tree longevity and productivity of stone fruit.
6) Improve the methods of rootstock identification. The use of new rootstocks can lead to errors in the propagation. In addition, all the new stocks are patented and the protection of the inventors rights requires accurate identification methods.
Barden, J.A., and M.E. Marini. 1992. Maturity and quality of 'Delicious' apples as influenced by rootstock. J. Amer. Soc. Hort. Sci. 117:547-550.
Barritt, B.H. 1992. Hybrid tree cone orchard system for apple. Acta Hort. 322:87-92.
Beckman, T.G., W.R. Okie, and S.C. Myers. 1992. Rootstocks affect bloom date and fruit maturation of 'Redhaven' peach. J. Amer. Soc. Hort. Sci. 117:377-379.
Beckman, T.G., J.A. Flore, and R.L. Perry. 1992. Short-term flooding affects gas exchange characteristics of containerized sour cherry trees. HortScience 27:1297-1301.
Brown, G.R. and D. Wolfe. 1992. Rootstock affects maturity of 'Starkspur Supreme Delicious' apples. HortScience 27:76.
Cummins, J.N. and H.S. Aldwinckle. 1992. Resistant host plants--The too-often absent component of integrated fruit production. Proc. Australian Soc. Hort. Sci. 1:157-163.
Cummins, J.N. and R.L. Andersen. 1992. A New York test of some advanced rootstock candidates for sweet cherry. Proc. Australian Soc. Hort. Sci. 1:165-169.
Cummins, J.N. and H.S. Aldwnicnkle. 1992. Geneva 65 (G.65)--A disease-resistant superdwarfing rootstock for apples. Compact Fruit Tree 25:61-64.
Ferree, D.C. 1992. Ten year summary of the performance of nine rootstocks in the NC-140 trial. Compact Fruit Tree 25:5-11.
Feerree, D.C. 1992. Performance over 10 years of 4 apple cultivars in intensive orchard systems. HortScience 27:619-620.
Feerree, D.C. 1992. Time of root pruning influences vegetative growth, fruit size, biennial bearing and yield of 'Jonathan' apple. J. Amer. Soc. Hort. Sci. 117:198-202.
Hoying, S. A. and T. L. Robinson. 1992. Effects of chainsaw girdling and rootpruning of apple trees. Acta Hort. 322:167-172.
Krzesinska, E. and A.N. Miller-Azarenko. 1992. Excised twig assay to screen cherry rootstocks for tolerance to Pseudomonas syringae pv. syringae. HortScience 27:153-155.
Reighard, G.L. 1992. Using interstems to delay bloom in peach. Compact Fruit Tree 25:90-91.
Robinson, T.L. 1992. Physiological basis for orchard system performance. Compact Fruit Tree 25:24-28.
Robinson, T. L. 1992. Performance of Y-shaped apple canopies at various angles in comparison with central leader trained trees. Acta Hort. 322:79-86.
Samimy, C. and J.N. Cummins. 1992. Distinguishing apple rootstocks by isozyme banding patterns. HortScience 27:829-831.
Schupp, J.R., D.C. Feerree, and I.J. Warrington. 1992. Influence of root pruning and deblossoming on growth, and yield of 'Golden Delicious' apple. J. Hort. Sci. 67:465-480.
Also in 1992: 16 grower-oriented publications, 7 research reports, 5 abstracts.
Autio, W.R. and F. W. Southwick. 1993. Evaluation of a spur and a standard strain of 'McIntosh' on three rootstocks and one dwarfing interstem over ten years. Fruit Var. J. 47:95-102.
Barritt, B.H. and B.J. Konishi. 1993. Influence of apple cultivar and canopy position on seasonal development of fruiting spurs. Fruit. Var. J. 47:5-12.
Bell, R.L., H.A. Quamme, R.E.C. Layne, and R.M. Skirvin. 1993. The pear. In: Advances in Fruit Breeding. ed.: J. Janick and J.N. Moore. Purdue Univ. Press, West Lafayette, IN.
Crassweller, R. M., G. M. Greene II, S. S. Miller, and V. Eby. 1993. A chemical thinning expert system on the Penn State Apple Orchard Consultant expert system. Acta Hort. 313:215-218.
Crassweller, R. M., J. W. Travis, P. H. Heinemann, and E. G. Rajotte. 1993. The actual and potential future use of expert system technology in horticulture. HortTechnology 3:203-208.
Crassweller, R. M., J. W. Travis, E. G. Jajotte, J. McClure, and P. H. Heinemann. 1993. Building expert systems for use by commercial farmers. Acta Hort. 313:205-208.
Embree, C.G., H.B. Lesser, and A.D. Crowe. 1993. Characterization of the KSC apple rootstocks. I. Growth and efficiency. J. Amer. Soc. Hort. Sci. 118:170-172.
Embree, C.G., H.B. Lesser, and A.D. Crowe. 1993. Characterization of the KSC apple rootstocks. III. Quality and overall performance. J. Amer. Soc. Hort. Sci. 118:177-180.
Ferree, D.C., K. Clayton-Greene, and B. Bishop. 1993. Influence of orchard management system on canopy composition, light distribution and net photosynthesis of apple trees. J. Hort. Sci. 68:377-392.
Granger, R.L., M. Meheriuk, S. Khanizadeh, and Y. Groleau. 1993. Performance of 'Starkspur Supreme Delicious' grown on 24 rootstocks in Quebec. Fruit Var. J. 47:226-229.
Krzesinska, E., A.N. Miller-Azarenko, and D. Gross. 1993. Inducing the syrB gene in Pseudomonas syringae pv. syringae in twig extracts from cherry genotypes. HortScience 28:335-337.
Lesser, H.B., C.G. Embree, and A.D. Crowe. 1993. Characterization of the KSC apple rootstocks. II. Precocity and productivity. J. Amer. Soc. Hort. Sci. 118:173-176.
Parker, M.L., J. Hull, and R.L. Perry. 1993. Orchard floor management affects peach rooting. J. Amer. Soc. Hort. Sci. 118:714-718.
Perry, R.L. and R.T. Fernandez. 1993. Apple rootstock performance in Michigan. Compact Fruit Tree 26:97-99.
Perry, R.L. and J.A. Flore. 1993. Management systems for new sweet cherry rootstocks. Compact Fruit Tree 26:116-119.
Perry, R.L., J.L. Runkel, and M.A. Longstroth. 1993. The effects of rootstock on the performance of Hedelfingen and Montmorency cherry in Michigan, USA. Proc. ISHS International Cherry Symposium, 14-18 June 1993, Budapest, Hungary.
Proebsting, E. and D. Ophardt. 1993. Cherry rootstocks in the Washington NC-140 trial. Compact Fruit Tree 26:116-113.
Quamme, H.A., and R.T. Brownlee. 1993. Early performance of micropropagated trees on several Malus and Prunus cultivars on their own roots. Can. J. Plant Sci. 73:847-855.
Robinson, T.L. and W.C. Stiles. 1993. Fertigation of young apple trees to improve growth and cropping. Compact Fruit Tree 26:61-65.
Robinson, T.L., S.A. Hoying, and W.H. Smith. 1993. Canopy design and management for improved orchard production efficiency. Compact Fruit Tree 26:46-49.
Robinson, T. L., J. Wünsche, and A. N. Lakso. 1993. The influence of orchard system and pruning severity on yield, light interception, conversion effciency, partitioning index and leaf area index. Acta Hort. 349:123-127.
Warmund, M.R., B.H. Barritt, J.M. Brown, K.L. Schaffer, and B.R. Jeong. 1993. Detection of vascular discontinuity in bud unions of 'Jonagold' apple on Mark rootstock with magnetic resonace imaging. J. Amer. Soc. Hort. Sci. 118:92-96.
Also in 1993: 42 grower-oriented publications, 4 research reports, 12 abstracts, 2 Masters theses.
Autio, W.R. 1994. Rootstock affects apple ripening, quality and storability. Compact Fruit Tree 27:41-47.
Autio, W.R. and D.W. Greene. 1994. Effects of growth retarding treatments on apple tree growth, fruit maturation, and fruit abscission. J. Hort. Sci. 69:653-664.
Barritt, B.H., M.A. Dilley, and B.S. Konishi. 1994. Influence of rootstock on 'Delicious' apple fruit shape. Fruit Var. J. 48:126-130.
Barritt, B.H., B.S. Konishi, and M.A. Dilley. 1994. Performance in Washington of 23 dwarfing apple rootstocks in 8 seasons with 3 varieties. Compact Fruit Tree 27:28-31.
Ferree, D.C. 1994. Early performance of two apple cultivars in three training systems. HortScience 29:1004-1007.
Ferree, D.C. 1994. Performance of eight strains of 'Rome Beauty' over eight years. Fruit Var. J. 48:240-244.
Ferree, D.C. 1994. Root pruning on root distribution of 'Melrose'/M.26 apple trees after nine years of root pruning. HortScience 29:76-78.
Ferree, D.C. 1994. Performance after 8 years of 20 dwarfing rootstocks on 3 cultivars. Compact Fruit Tree 27:32-36.
Ferree, D.C. and J.C. Schmid. 1994. Early production of apple cultivars on M.9 and Mark rootstock. Fruit Var. J. 48:130-132.
Ferree, D.C., D.D. Miller, and M. Lynd. 1994 Performance of AL800 as an apple rootstock and interstem in Ohio. Fruit Var. J. 48:186-191.
Greene, D.W. and W.R. Autio. 1994. Notching techniques increase branching of young apple trees. J. Amer. Soc. Hort. Sci. 119:678-682.
Meheriuk, M., H.A. Quamme, and R.R. Brownlee. 1994. Influence of rootstocks on fruit quality, size, and yield of Macspur apples. Fruit Var. J. 48:93-97.
Melakeberhanm H., G.W. Bird, and R.L.Perry. 1994. Plant-parasitic nematodes associated with cherry rootstocks in Michigan. J. Nematology 26:762-772.
Morin, F., C.Hamel, J.A. Fortin, R.L. Granger, and D.L. Smith. 1994. Apple rootstock response to vesicular-arbuscular mycorrhizal fungi in a high phosphorus soil. J. Amer. Soc. Hort. Sci. 119:578-583.
Okie, W.R., T.G. Beckman, A.P. Nyczepir, G.L. Reighard, W.C. Newall, Jr., and E.I. Zehr. 1994. BY520-9, a peach rootstock for the southeastern United States that increases scion longevity. HortScience 29:705-706.
Okie, W.R., G.L. Reighard, T.G. Beckman, A.P. Nyczepir, C.C. Reilly , E.I. Zehr, W.C. Newall, Jr., and D.W. Cain. 1994. Field screening Prunus for longevity in the southeastern United States. HortScience 29:673-677.
Quamme, H.A. and E.J. Hogue. 1994. Improved rooting of Ottawa apple rootstock by softwood cuttings using micropropagated plants as a cutting source. Fruit Var. J. 48:170-173.
Robinson, T.L., S.A. Hoying, and W.H. Smith. 1994. New York orchard system demonstrations: What we have learned so far. Compact Fruit Tree 27:73-77.
Rom, C.R. 1994. Balancing growth and cropping: Which comes first, the canopy or the crop? Compact Fruit Tree 27:53-59.
Rom, C.R. 1994. Managing the central leader. Compact Fruit Tree 27:83-84.
Rom, C.R. 1994. Apple cultivars for the Southeastern United States: Trends perspectives, and prospects. Compact Fruit Tree 27:160-164.
Warmund, M.R. and B.H. Barritt. 1994. Survival and growth of 'Empire' apple trees chip budded onto Mark or M.9 rootstock. Fruit Var. J. 48:245-250.
Also in 1994: 38 grower-oriented publications, 6 research report, 9 abstracts, 2 Masters theses, 2 PhD Dissertations.
Autio, W. R., R. A. Hayden, W. C. Micke, and G. R. Brown. 1995. Rootstock affects ripening, color and shape of 'Starkspur Supreme Delicious' apples in the 1984 NC-140 Cooperative Planting. Compact Fruit Tree 28:52-59.
Barden, J. A. 1995. Experience in Virginia with slender spindle, vertical axe, and central leader on several rootstocks with Delicious and Empire. Compact Fruit Tree 28:9-11.
Barritt, B. H., B. S. Konishi, and M. A. Dilley. 1995. Performance of three apple cultivars with 23 dwarfing rootstocks during 8 seasons in Washington. Fruit Var. J. 49:158-170.
Bower, K. N., L. P. Berkett, and J. F. Costante. 1995. Non-target effect of a fungicide spray program on phytophagous and predacious mite populations in a scab resistant apple orchard. Environmental Entomology. 24:423-430.
Embree, C. G. 1995. A photographic description of the fruit of certain apple rootstocks. Fruit Var. J. 49:59-64.
Fernandez, R. T., R. L. Perry, and D. C. Ferree. 1995. Root distribution patterns of nine apple rootstocks in two contrasting soil types. J. Amer. Soc. Hort. Sci. 120:6-13.
Ferree, D. C. 1995. Performance of apple rootstocks in the NC-140 trial. Compact Fruit Tree 28:49-51.
Ferree, D. C., P. M. Hirst, J. C. Schmid, and P. E. Dotson. 1995. Performance of the apple cultivars with 22 dwarfing rootstocks during 8 seasons in Ohio. Fruit Var. J. 49:179-189.
Granger, R. L., M. Meheriuk, S. Khanizadeh, and Y Groleau. 1993. Performance of 'Starkspur Supreme Delicious on 24 rootstocks in Quebec. Fruit Var. J. 47:226-229.
Hirst, P. M. and D. C. Ferree. 1995. Rootstock effects on shoot morphology and spur quality of 'Delicious' apple and relationships with precocity and productivity. J. Amer. Soc. Hort. Sci. 120:622-634.
Hirst, P. M. and D. C. Ferree. 1995. Effect of rootstock and cultivar on the growth and precocity of young apple trees. Fruit Var. J. 49:34-41.
Hooker, J. E., K. E. Black, R. L. Perry, and D. Atkinson. 1995. Arbuscular mycorrhizal fungi induced alteration to root longevity of poplar. Plant and Soil Vol. 172:327-329.
Landry, B. S., R. Q. Li, W. Y. Cheung, and R. L. Granger. 1994. Phylogeny analysis of 25 apple rootstocks using RAPD markers and tactical gene tagging. Theor. Appl. Genet. (Springer-Verlag) 89:847-852.
Lu, Z. X., G. L. Reighard, W. V. Baird, A. G. Abbott, and S. Rajapakse. 1995. Identification of peach rootstock cultivars by RAPD markers. HortScience 31:127-129.
Mandre, O., M. Rieger, S. C. Myers, R. Severson, and J. L. Regnard. 1995. Interaction of root confinement and fruiting in peach. J. Amer. Soc. Hort. Sci. 120:228-234.
Morin, F., C. Hamel, J. A. Fortin, R. L. Granger, and D. L. Smith. 1994. Apple rootstock response to vesicular-arbuscular mycorrhizal fungi in a high phosphorus soil. J. Amer. Soc. Hort. Sci. 119:578-583.
Olien, W. C., D. C. Ferree, B. L. Bishop, and W. C. Bridges, Jr. 1995. Prediction of site index and apple rootstock performance from environmental variables. Fruit Var. J. 49:179-189.
Perry, R., S. Swinton, and P. Schwallier. 1995. Performance and labor requirements for orchard systems in the Michigan NC-140 trial. Compact Fruit Tree 28:12-14.
Reighard, G. L. 1995. Use of peach interstems to delay peach phenology. Acta Hort. 395:201-207.
Robinson, T. L. 1995. A comparison of orchard systems with 'Empire' and 'Jonagold' on various rootstocks in New York. Compact Fruit Tree 28:5-8.
Tukey, L. D. 1995. An apple rootstock story to be told: from M.26 to M.27. Compact Fruit Tree 28:81-85.
Wunsche, J. N., A. N. Lakso, and T. L. Robinson. 1995. Comparison of four methods for estimating total light interception by apple trees of varying forms. HortScience 30:272-276.
Also in 1995: 42 grower-oriented publications, 3 research report, 4 abstracts.
Autio, W. R., R. A. Hayden, W. C. Micke, and G. R. Brown. 1996. Rootstock affects ripening, color, and shape of 'Starkspur Supreme Delicious' apples in the 1984 NC-140 cooperative planting. Fruit Var. J. 50:45-53.
Barritt, B. H., B. S. Konishi, and M. A. Dilley. 1996. Performance of three apple cultivars with 18 vigorous rootstocks during 9 seasons in Washington. Fruit Var. J. 50: (in press).
Beckman, T. G., G. L. Reighard, W. R. Okie, A. P. Nyczepir, E. I. Zehr, and W. C. Newall. 1996. History, current status and future potential of GuardianTM peach rootstock. Acta Hort. (in press).
Conrod, J. D., J. Larson, and E. Hoover. 1996. Rootstock effects terminal bud set in 'Starkspur Supreme' Delicious apple. Fruit Var. J. 50: (in press).
Flore, J.A. and R.L. Perry. 1996. Can shelters over cherry trees to prevent rain induced cracking be proftitable. Proc. Int. Conference on Cracking of Cherries. Michigan State Univ., Dept. of Hort. Science Special Report. pp78-79.
Granger, R.L., S. Khanizadeh, Y. Groleau, and C.N. Fortin. 1996. 'Belmac' apple. HortScience 31: (in press).
Granger, R.L., S. Khanizadeh, Y. Groleau, and C.N. Fortin. 1996. 'Primevere' apple. HortScience 31: (in press).
Hirst, P.M. and D.C. Ferree. 1996. Effect of rootstock on bud development and flower formation of 'Starkspur Supreme Delicious' apple. Fruit Var. J. 50:25-34.
Kaps, M.L., G.M.Greene, and D.C. Ferree. 1996. Performance of 'Starkspur Supreme Delicious' apple over 10 years at three axillary sites. Fruit Var. J. 50:41-44.
Longstroth, M. and R.L. Perry. 1996. Selecting the orchard site, orchard planning and establishment. In: Cherrries: Crop Physiology, Production;, and Uses. A.D. Webster and N.E. Looney (eds.) CAB International. Wallingford, UK, pp.203-222.
NC-140. 1996. Performance of the NC-140 Cooperative Apple Rootstock Planting: I. Survival, tree size, yield and fruit size. Fruit Var. J. 50:6-11.
NC-140. 1996. Performance of the NC-140 Cooperative Apple Rootstock Planting: II. A 10 year summary of TCA, yield, and yield efficiency at 31 sites. Fruit Var. J. 50:11-18.
NC-140. 1996. Horticultural characteristics of 'Starkspur Supreme Delicious' apple on 15 rootstocks at 24 sites. Fruit Var. J. 50:18-24.
NC-140. 1996. Rootstock and scion cultivar interact to affect apple tree performance: A five-year summary of the 1990 NC-140 cultivar/rootstock trial. Fruit Var. J. 50:175-187.
Neilsen, G. and F. Kappel. 1996. 'Bing' sweet cherry leaf nutrition is affected by rootstock. HortScience 31:(in press).
Olein, W.C., D.C. Ferree, and B.L. Bishop. 1996. Performance potential and stability of 15 apple rootstocks as affected by North American growing sites over the period 1984-1993. Fruit Var. J. 50:62-68.
Olein, W.C. and A.N. Lakso. 1996. Effect of rootstock on apple (Malus domestica) water relations. Physiologia Plantarum 67:421-430.
Perry, R., J. Flore, M.Whalon, J. Johnson, A. Jones, G. VanEe, and C. Edson. 1996. The development of integrated fruit management programs in Michigan, USA. Int. Conference on Integrated Fruit Production. IOBC wprs Bull. 19(4):85-89.
Perry, R., G. Lang, R. Andersen, L. Anderson, A. Azarenko, T. Facteau, D. Ferree, A. Gaus, F. Kappel, F. Morrison, C. Rom, T. Roper, S. Southwick, G. Tehrani, and C. Walsh. 1996. Performance of the NC-140 Cherry rootstock trials in North America. Compact Fruit Tree 29:37-56.
Reighard, G. L., C. J. Graham, and D. R. Ellis. 1996. Efficacy of nutrient supplements and rootstock on mineral nutrition, growth and survival of peach on replant sites. Acta Hort. (in press).
Reighard, G. L., W. C. Newall, T. G. Beckman, W. R. Okie, E. I. Zehr, and A P. Nyczepir. 1996. Field performance of Prunus rootstock cultivars and selections on replant soils in South Carolina. Acta Hort. (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., S.A. Hoying, and W.H. Smith. 1996. Apple orchard systems trials in New York. Compact Fruit Tree 29:107-113.
VanVranken, R.W. and W.P. Cowgill, Jr. 1996. Utilizing electronic mail list discussion groups on the internet to enhance communication in specific commodity groups. HortTechnology 6:318-324.
Warmund, M.R., W.R. Autio, J.A. Barden, J.N. Cummins, P.A. Domoto, C.G. Embree, R.L. Granger, F.D. Morrison, J.R. Schupp and E. Young. 1996. Blackheart injury in 'Starkspur Supreme Delicious' on 15 rootstocks in the 1984 NC-140 cooperative planting. Fruit Var. J. 50:55-62.
Wunsche, J. N., A. N. Lakso, T. L. Robinson, F. Lenz, and S. S. Denning. 1996. The bases of productivity in apple production systems: the role of light interception by different shoot types. J. Amer. Soc. Hort. Sci. 121:886-893.
Also in 1996: 45 grower-oriented publications, 15 research report, 14 abstracts.
1997 (in preparation, submitted, or in press)
Anderson, J.L., T.E. Lindstrom, and J.I. del Real-Laborde. 1997. Rootstock effects on growth and productivity of 'Montmorency' sour cherry. Acta Hort. 410: (in press).
Autio, W.R., D.W. Greene, and W.J. Lord. 1997. Performance of 'McIntosh' apple trees on seven rootstocks over 10 years and a comparison of methods of presenting productivity. HortScience 31:(in press).
Autio, W.R., J.R. Schupp, D.C. Ferree, R. Glavin, and D.L. Mulcahy. 1997. Identification of apple rootstocks by random amplified polymorphic DNA's (RAPDs) HortScience (in preparation).
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 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).
Fernandez, R.T, R.L. Perry, and J.A. Flore. 1997. Water stress physiology of apple rootstocks. J. Amer. Soc. Hort. Sci. (in press).
Fernandez, R.T., M. McLean, J.A. Flore, and R.L. Perry. 1997. Carbon partitioning of flooded apple on dwarfing rootsocks. J. Amer. Soc. Hort. Sci (in press).
Khanizadeh, S., D. Buszard, and R.L. Granger. 1996. Cultural and environmental factors associated with winter injury to apple trees in Quebec (submitted).
Khanizadeh, S., R.L. Granger, G.L. Rousselle, M.Meheriuk and Y.Groleau. 1997. Perfomance of 'Spartan' apple on several rootstocks from a breeding program at St-Jean-sur-Richelieu. (submitted).
Lakso, A.N. and T.L. Robinson. 1997. Principles of orchard systems management--Optimizing supply, demand and partitioning in tree fruits. Acta Hort (in press).
Lang. G., W. Howell, D. Ophardt, and G. Mink. 1997. Biotic and abiotic stress responses of interspecific hybrid cherry rootstocks. Acta Hort. (in press).
Perry, R., G. Lang, R. Andersen, A. Azerenko, T. Facteau, D. Ferree, A. Gaus, F. Kappel, F. Morrison, C. Rom, T. Roper, S. Southwick, G. Tehrani, and C.Walsh. 1997. Performance of the NC-140 cherry rootstock trails in North America. Acta Hort. (in press).
Perry, R., S. Swinton, and P. Schwallier. 1997. Labor requirements for Empire and Jonagold apple as affected by rootstock and three orchard systems in the Michigan NC-140 trial. Acta Hort. (in press).
Perry, R. 1997. The performance of Jonagold and Empire apple in an NC-140 rootstock and orchard systems trial in Michigan. Acta Hort. (in press).
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. (in press).
Robinson, T.L., J.N. Cummins, and S.A. Hoying. 1997. Commercial orchard evaluation of the new Cornell-Geneva rootstocks. Acta Hort. (in press).
Rom, C.R., W.R. Autio, and F. Morrison. 1997. Rootstock affects elemental composition of 'Starkspur Supreme Delicious' apple trees in the 1984 NC-140 Cooperative planting Fruit Var. J. 51:(in press).