3. M9 NIC29 A virus-free Belgian subclone of M9 that is slightly more vigorous than most others M9 clones.

Transcription

1 New Dwarfing Apple Rootstocks for Improving Efficiencies in Ontario Apple Orchards J.W. Zandstra G.J. Watt CORD IV Project # Final Report 15 November, 2007 Prepared for: Ontario Apple Growers PO Box 100, Vineland Station, Ontario, L0R 2E0 120 Main Street East Ridgetown, ON N0P 2C0 Phone: Fax:

2 Executive Summary Rootstock development objectives are moving more towards grower friendly characteristics, including insect and disease resistance and cold tolerance. Many newer dwarfing rootstocks included in this project demonstrate some degree of tolerance to fire blight, a very devastating bacterial disease (E. amylovora) presently controlled only by Streptomycin. The Vineland series of apple rootstocks, aside from demonstrating resistance to fire blight, have also been shown to be very cold tolerant. This characteristic will be useful to growers in the harsher regions of the province. Selecting the proper rootstock/scion combination is a critical part of planning an orchard. Many factors contribute to the final tree size and potential yield efficiency. While scion vigor, soil texture, soil fertility, water availability, climate, orchard management and training systems all contribute, the rootstock generally has the greatest influence on final tree size. Although the rootstocks used in this study were generally similar in reported vigor, there was a significant range in vigor, as is indicated by trunk cross sectional area. When averaged across the three cultivars, the ranking (from most to least vigorous) is M 26, PL 80, V 1, M 9 EMLA, Pajam 2, M 9 NIC 29, M 9 T337, C.G.16, V3, and B 9 ;this ranking was generally similar within each rootstock. Yields in 2007 were considerably greater than previous years as the trees were approaching a mature size. Gala on the rootstocks Pajam 2 and V3 produced the greatest cumulative yields and tended to have the greatest fruit yield consistently over the 4 years of harvest. Pajam 2 rootstock resulted in the largest fruit of all rootstocks, while V3 had one of the smallest, suggesting that fruit number rather than fruit size had a greater influence of fruit yield. B9 produced a weak tree, with small fruit and low yields consistently across all three cultivars. Of the rootstocks evaluated on the variety Honeycrisp, M26 and M 9 NIC 29 provided the greatest cumulative fruit yields. With this relatively weak growing scion variety, yields generally increased as rootstock vigor increased; however the top yielding rootstocks were not the most vigorous rootstocks. Fruit size tended to increase on the more vigorous rootstocks, with the most vigorous rootstock V1 producing the largest fruit. Tree yield efficiency tended to improve with the weaker rootstocks, as the most efficient tress were on the relatively weak rootstocks V3 and B9. Fruit yields and fruit size also tended to increased as Shizuka was grown on more vigorous rootstocks. Yield efficiency increased as rootstock vigor decreased. Fireblight was not noticed in the trials over the 3 years of this project. Crispin trees on M26 were planted within the Shizuka planting in order to compare the incidence of blister spot. While Shizuka fruit did show small amounts of blister spot when the condition was present, it is clearly more tolerant to this disease than Crispin (data not shown). 2

3 Project Results and Milestones Research was conducted for three years beginning in 2005 to document the performance of the apple cultivars Honeycrisp, Gala, and Shizuka on 10 dwarfing rootstocks, some of which show varying degrees of fireblight resistance. The rootstocks included M26 (standard comparison), M9 EMLA, M9 NIC29, M9 Pajam 2, M9 T337, Pi-80 Select (synonyms: Pillnitzer 80, PiR 80, Pi 80, Supporter 4), B9*, V1*, V3*, and CG16*. (Note: * indicates rootstocks with reported tolerance to fireblight). Honeycrisp was not available on the M9 EMLA rootstock, and Shizuka was not available of on the CG16 rootstock. Plots were established in May, 2002 Cedar Springs Research Station in Blenheim ON. The three scion varieties (Honeycrisp, Royal Gala, and Shizuka) were evaluated separately on the 10 rootstocks listed earlier. The experimental design consists of a randomized complete block, with 10 single tree replicates. All trees are spaced 2.5 m (8 ft) in the row, with 4.5 m (15 ft) between rows. A slender spindle training system is being used at Cedar Springs. Data will be collected on tree vigor, yield, fruit size and fruit quality. The incidence and spread of naturally occurring fireblight infections was also recorded. A. Rootstock Descriptions 1. M.26 (standard comparison) This precocious, and productive semi-dwarfing rootstock produces a tree approximately 55-60% the size of a seedling tree. It is the most common dwarfing rootstock used in Ontario, with approximately 40% of the trees on dwarfing rootstocks on M M.9 EMLA The original M9 rootstock produces at tree approximately 45-50% the size of a seedling tree. It is very precocious and productive. Fruit size tends to be slightly larger than on some other rootstocks and it may ripen slightly earlier. Its roots are brittle and the trees require support. It is susceptible to fire blight and woolly apple aphid, but very resistant to collar rot, produces few suckers, maintains good fruit size, and is extremely productive and precocious. A virus-free clone of M.9, denoted by the industry as M.9 EMLA or M.9 E, was developed in Britain by heat treatment and is slightly more vigorous than the original M.9 (M.9 is approximately 30% smaller than M.26 E). 3. M9 NIC29 A virus-free Belgian subclone of M9 that is slightly more vigorous than most others M9 clones. 4. M9 Pajam 2 Originating in France, Pajam 2 is possibly not a true subclone of M.9, but is treated as if it is. It is among the largest of the M.9 types 5. M9 T337 3

4 A virus-free Dutch subclone of M.9 with improved propagation characteristics; it is less vigorous than M.9E 6. Pi-80 Select (synonyms: Pillnitzer 80, PiR 80, Pi 80, Supporter 4) This is a M.9 X M.4 Malus cross which is similar in precocity and productivity to M.26, and is more yield efficient in some German trials. Tree support is usually recommended for young orchards, and anchorage is reported to be better M.26. The rootstock is extremely susceptible to fire blight (comparable to M.26) and powdery mildew. Little information is available on its susceptibility to crown rot and woolly apple aphid. The stock has moderate to excellent winter hardiness; however further testing of this is required. The stock also has few root suckers and burrknots. It performs well in the stoolbed, and is easier to propagate than M.26. Pi-80 Select has been planted in North America very recently in a few small trial plots. Pi-80 Select may become a strong competitor with M.26. Reports vary, but Pi-80 Select is usually reported to impart slightly more vigor on the scion than M.26. Extensive testing and planting in Europe has generated strong interest in this rootstock. 7. B.9 Very similar to M.9 in size, precocity, and productivity. It originated in the former Soviet Union from a cross between M.8 and Red Standard and was introduced in Its leaves and wood tissue have a dark reddish green colour. It is becoming of commercial importance in some areas especially because of its cold hardiness and reported slight tolerance to fire blight. 8. V.1 Originated in Ontario from a cross between M.9 and Kerr crab apple. It produces a tree which is similar to M.26 in size. The rootstock is precocious and productive. It is very cold hardy and resistant to fire blight. 9. V.3 Originated in Ontario from a cross between M.9 and Kerr crab apple. It produces a tree which is slightly smaller than M.9 EMLA (similar to the M.9' clones M.9 T337' and M.9 Flueren 56') but similar to M.9 in precocity and productivity. The rootstock requires support. Trees on V.3' have a similar propensity to form root suckers and appear to be as productive as the M.9' clones. Trees on V.3 have shown field immunity to fire blight and are very cold hardy. 10. CG.16 CG.16 is a cross of Ottawa 3 and Malus floribunda released by Cornell University. It is similar in vigour, productivity, and precocity as M.9. It s advantage over M.9 is its resistance to fire blight. The rootstock is hypersensitive to latent virus, therefore virus free scion wood is required. This stock is not widely tested and therefore should be considered on a trial basis. This project had the following 6 objectives: 1. Determine the precocity and productivity of new dwarfing apple rootstocks in order to make recommendations to Ontario apple producers 4

5 2. Quantify the performance of various rootstock/scion combinations under different orchard, environment and management systems. 3. Continue the commercial development of the Vineland series rootstocks 4. Evaluate the vigor and performance of Honeycrisp on more vigorous rootstocks 5. Document Shizuka performance and fruit quality in comparison to Crispin 6. Document the incidence and spread of naturally occurring fireblight infections Discussion Although the rootstocks were generally similar in reported vigor, there was a significant range in vigor, as is indicated by trunk cross sectional area. When averaged across the three cultivars, the ranking (from most to least vigorous) is M 26, PL 80, V 1, M 9 EMLA, Pajam 2, M 9 NIC 29, M 9 T337, C.G.16, V3, and B 9 (Table 1). This ranking was generally similar within each rootstock, with few exceptions (for example, M 9 EMLA falls behind M 9 NIC 26 in Gala, rather than 2 places above it (Table 1). Yields in 2007 were considerably greater than previous years as the trees were approaching a mature size. Gala on the rootstocks Pajam 2 and V3 produced the greatest cumulative yields and tended to have the greatest fruit yield consistently over the 4 years of harvest. Pajam 2 rootstock resulted in the largest fruit of all rootstocks, while V3 had one of the smallest, suggesting that fruit number rather than fruit size had a greater influence of fruit yield. B9 produced a weak tree, with small fruit and low yields. (Table 2). V3 was the most efficient tree in 2007, with 1.13 kg of marketable fruit produced for each cm 2 of trunk cross sectional area. (Table 2). With this variety, rootstock vigor did not appear to correlate with total yields (Table 2). Of the rootstocks evaluated on the variety Honeycrisp, M26 and M 9 NIC 29 provided the greatest cumulative fruit yields (Table 3). With this relatively weak growing scion variety, yields generally increased as rootstock vigor increased; however the top yielding rootstocks were not the most vigorous rootstocks. Fruit size tended to increase on the more vigorous rootstocks, with the most vigorous rootstock V1 producing the largest fruit. Tree yield efficiency tended to improve with the weaker rootstocks, as the most efficient tress were on the relatively weak rootstocks V3 and B9 (Table 3). Fruit yields and fruit size tended to increased as Shizuka was grown on more vigorous rootstocks (Table 4). M26 produced the greatest yield, while V1 had the largest fruit. Yield efficiency increased as rootstock vigor decreased. Fireblight was not noticed in the trials over the 3 years of this project. One Gala tree died over the spring of 2007, which may have been fireblight, but otherwise there was no indication of this disease. Crispin trees on M26 were planted within the Shizuka planting in order to compare the incidence of blister spot. Fruit yield and size were similar to Shizuka. While Shizuka fruit did show small amounts of blister spot when this condition was present, it is clearly more tolerant to this disease than Crispin (data not shown) 5

6 Table 1. Trunk cross sectional area of 3 apple cultivars on various rootstocks, sorted from most to least vigorous. Cedar Springs Research Station, Ridgetown Campus, University of Guelph Rootstock Cultivar Average Gala Honeycrisp Shizuka M a 27.3 ab 60.7 a 46.1 PL a 28.4 ab 52.2 b 45.0 V ab 31.7 a 48.8 bc 43.2 M 9 EMLA 37.8 c cd 41.5 Pajam b 24.4 bc 45.4 bcd 38.7 M 9 NIC ab 25.1 bc 41.4 d 38.4 M 9 T c 21.9 cd 40.3 d 33.7 C.G c 21.8 cd V c 17.6 d 30.6 e 28.4 B d 9.6 e 32.3 e 22.1 LSD (0.05) CV P-value

7 Table 2. Fruit yields (kg/tree) of Royal Gala on various rootstocks sorted from most to least vigorous for Gala. Cedar Springs Research Station, Ridgetown Campus, University of Guelph Yield of Gala (kg/tree) 2007 Rootstock Cumulative Yield Fruit Size (g) Yield Efficiency (kg/cm 2 ) Pl bcd abc 0.76 d M cd c 0.75 d V abc bc 0.90 cd M.9 NIC ab ab 0.95 bc Pajam a a 1.07 ab M.9 T a-d abc 1.13 a M. 9 EMLA d c 0.98 abc V bcd c 1.15 a C.G d bc 1.00 abc B e d 0.87 cd LSD (0.05) CV P-value

8 Table 3. Fruit yields (kg/tree) of Honeycrisp on various rootstocks sorted from most to least vigorous for Honeycrisp. Cedar Springs Research Station, Ridgetown Campus, University of Guelph Yield of Honeycrisp (kg/tree) 2007 Rootstock Cumulative Yield Fruit Size (g) Yield Efficiency (kg/cm 2 ) V a a 1.64 abc Pl cde bc 1.33 c M ab ab 1.65 abc M.9 NIC bc abc 1.68 abc Pajam bcd bc 1.64 abc M.9 T bcd bc 1.82 a C.G e cd 1.35 bc V de bc 1.89 a B f d 1.69 ab LSD (0.05) CV P-value

9 Table 4. Fruit yields (kg/tree) of Shizuka on various rootstocks sorted from most to least vigorous for Shizuka. Cedar Springs Research Station, Ridgetown Campus, University of Guelph Yield of Shizuka (kg/tree) 2007 Rootstock Cumulative Yield Fruit Size (g) Yield Efficiency (kg/cm 2 ) M a a 1.09 cd Pl ab ab 1.19 bcd V bc abc 1.11 cd Pajam ab abc 1.37 ab M. 9 EMLA cd e 1.08 d M.9 NIC ab bcd 1.44 a M.9 T ab bc 1.46 a B d f 1.37 ab V d de 1.46 a LSD (0.05) CV P-value

10 Milestones 1. Conduct research and summarize data: April, February, completed 2. Conduct research and summarize data: April, February, completed 3. Communicate with Industry: November, April presented data to the Ontario Apple Growers: February, Conduct research and summarize data: April, December, completed 5. Communication with Industry: September, December, a final report will be forwarded to the Ontario Apple Growers in November, 2007 Communication Plan Trial results were presented to representatives of the Ontario Apple Growers in February, A final report will be forwarded to the Ontario Apple Growers at the completion of this project A journal article will be prepared in collaboration with Dr. John Cline. Acknowledgment This project is funded in part through contributions by Canada and the Province of Ontario under the Canada-Ontario Research and Development (CORD) Program, an initiative of the federal-provincial-territorial Agricultural Policy Framework designed to position Canada s agri-food sector as a world leader. The Agricultural Adaptation Council administers the CORD program on behalf of the province. This support will be recognized in all future communication related to this project. 10