Sweet and Tart Cherry Rootstocks for Ontario March, 2004
Dr. J. A. Cline, D. Norton University of Guelph, Vineland Campus Choosing a suitable rootstock for a new orchard has economic and orchard management consequences. A great number of cherry rootstocks are available for tender fruit producers – but many are not suitable for our climate, cultivars, or orchard systems. The Tree Fruit Research program at the University of Guelph, Vineland campus has been actively involved in rootstock research for peach, nectarine, plum and cherry production in Ontario. Long-term research is ongoing to assess size controlling characteristics of a number of rootstocks from around the world. The information gathered from these experiments is extremely useful in determining the environmental and genetic interactions rootstocks have on yield, precocity, tree performance, longevity, resistance to disease, winter injury, and tendency to sucker. This article will provide a brief summary of some of our most recent results from studies conducted in Vineland on sweet and tart cherries. Sweet Cherry New rootstocks are needed to keep the Ontario cherry industry competitive by reducing tree size, while increasing productivity and maintaining high fruit quality. A smaller tree can reduce expensive harvest labour costs, improve harvest efficiency, pest control, and facilitate new strategies to avoid rain-induced fruit cracking and bird damage. Ten trees each of Hedelfingen on 14 different rootstock (Edabriz, Gisela 195-20, Gisela 209-1, Gisela 4 (GI 473-10), Gisela 5 (GI 148-2), Gisela 6 (GI 148-1), Gisela 7 (GI-148-8), Mahaleb, Mazzard, Wieroot 10, Wieroot 13, Wieroot 158, Wieroot 53, Wieroot 72) were planted in 1998 at the Horticultural Experiment Station, Vineland at a spacing of 5.0 m within and 5.5 m between rows (364 trees/hectare; 147 trees/acre). The block, which completed its third year of fruiting in 2003, is not staked or irrigated, and is trained to a central leader with branch manipulation encouraged rather than pruning. Significant differences in yield, mean fruit weight, yield efficiencies, cumulative yield efficiencies, and tree growth (TCSA) have been observed. Apart from the loss of two trees on Mahaleb rootstock in the spring of 2001, all trees have generally grown very well. Highlights of this research are: • Wieroot 10, Mahaleb and Mazzard rootstocks Fig. 1 Tree size and cumulative yield of Hedelfingen in continued to produce the relation to rootstock largest trees based on trunk circumference (Fig. 35 100 1) Tree size Cumulative yield 30 • Gisela 209-1 and Gisela 4 80 25 rootstocks have been the 20 60 most dwarfing - 17, and 18 15 % of Mazzard, respectively 40 (Fig. 1) 10 20 • Cumulative yield efficiency 5 has been greatest on 0 0 Gisela 6 and Weiroot 10 while the lowest on Mazzard (Fig. 1)
Tree size (% of Mazzard)
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Rootstocks Origins Gisela Series Gisela rootstocks were developed in the 1960’s by Drs. Werner Gruppe and Hanna Schmidt at the Justus Leibig University, Giessen, Germany. Several of the more promising selections were imported into the United States and Canada in the 1980’s. Four of these have become commercially available: Gisela 5, Gisela 6, Gisela 7, and Gisela 12. Size control ranges from 45 to 80 percent of the size of Mazzard. Initial reaction was very favorable, but in recent years there has been concern about virus susceptibility, small fruit size when over-cropped which may also lead to poor canopy development. The Gisela series are reported to be winter hardy and tolerant of wet soils. Gisela® 5: Tested as Gi148/2, it is reportedly very precocious, producing a tree about 50 percent the size of Mazzard. The rootstock seems to induce an open canopy with wide branch angles. Trees produce few suckers. Gisela® 6: Tested as Gi 148/1, it is a very precocious semi-dwarf rootstock that produces trees about 65 to 95 percent of the size of trees on Mazzard. Extra care must be taken to ensure that desired shoot extension growth is maintained because of its potential to overbear in its formative years, and for the same reason requires support for its heavy crop loads. Gisela® 6 is reported to be tolerant of viruses., has a wide range of soil adaptability, and apparently does well in heavier soils. It has good resistance to bacterial canker and has shown no variety incompatibilities. Gisela® 7: Tested as Gi148/8, it is reported to be about 50 percent the size of Mazzard. The rootstock produces some suckers. Support is also recommended for trees on this rootstock. Gisela 7 in recent research has shown some sensitivity to Prunus Necrotic Ringspot virus. Therefore, nematode management strategies for peaches should also be used when planting this rootstock. Gisela® 12: Tested as Gi195/2, this is a precocious, semi-dwarf type producing a tree about 60-70% the size of Mazzard. It is reported to have good virus resistance and does not sucker. The tree structure is open and spreading, has wide soil adaptability and apparently does well on heavy soils. It requires a management system designed to maintain extension growth to balance its precocity and high bloom density. Although Gisela 12® is well anchored, support is recommended to carry its heavy crop.
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Root suckering has only been minor to date In 2003, Wieroot 72, Mazzard, Wieroot 158 and Wieroot 10 produced the largest fruit while Gisela 209-1 produced the smallest. In 2003, Gisela 6, Wieroot 10 and Wieroot 158 produced the heaviest yields while Gisela 209-1 produced the lightest yields (Fig. 2)
Fig. 2 Yield and mean fruit weight of Hedelfingen in 2003 in relation to rootstock
Yield 25 Yield (kg/tree) 20 15 10 5 0 Mean fruit weight 8 7 6 5 4 3 2 1 0 Mean fruit weight (g)
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Weiroot Series The Weiroot series of rootstocks were selected at Weihenstephan near Munich, Germany from wild sour cherry species growing in Bavaria. Originally, three clones were released for testing, numbers 10, 13 and 14. Although good compatibility with Van, Merton Glory and Merpet sweet cherry cultivars has been good in UK trials, problems of incompatibility with some cherry cultivars has been reported in Germany and Switzerland. Experiments at East Malling showed sweet cherry trees on Weiroot clones 10 and 13 to be extremely productive and of vigour approximately 66% the size of Mazzard. Several new Weiroot selections (clones 53, 72, 158) may be more compatible with sweet cherry scions. Trees on clones 53 and 72 are reported to crop very well and have size controlling ability. These are worthy of further evaluation in Ontario. Weiroot 10: Slightly smaller than Mazzard. Sensitive to prune dwarf virus (PVD) and prunus nectrotic ringspot virus (PNRSV). Excellent productivity and fruit size, even when cropped heavily. Weiroot 13: 84% the size of Mazzard. Poor productivity and fruit size in comparison with other Weiroot and Gisela selections. Weiroot 53: 30% the size of Mazzard. Slightly higher productivity than Weiroot 13. Weiroot 72: is approximately 40%- the size of Mazzard . Resistant to PVD and PNRSV. While cumulative yields have been only moderate, good fruit size has been observed. Weiroot 158: is approximately 60% t the size of Mazzard. Resistant to PVD and PNRSV. Good productivity and fruit size in heavily cropping years. Perhaps a more suitable rootstock for self-fruitful selections where small fruit size on Gisela 6 has been experienced. Further testing is required.
Sour Cherry The standard rootstock for sour cherry is Mahaleb. This rootstock is productive, however, an understock is needed with greater tree longevity where Phytophthora root rot and other soilborne diseases exist or when trees are planted in heavy or shallow soils. Ten trees each of Montmorency on 12 different rootstock (Edabriz, Gisela 195-20, Gisela 209-1, Gisela 5 (GI 148-2), Gisela 6 (GI 148-1), Gisela 7 (GI-148-8), Mahaleb, Wieroot 10, Wieroot 13, Wieroot 158, Wieroot 53, Wieroot 72 ) were planted in 1998 at the Horticultural Experiment Station, Vineland, at a spacing of 5.0 m within and 5.0 m between rows (400 trees/hectare; 162 trees/acre). Trees were not staked or irrigated and were trained to a central leader orchard system. Performance overall was good in 2003. Significant differences in tree size exist between rootstocks (Fig 2).
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Summary
Yield Mean fruit weight New options for reducing the tree size of sweet cherry trees is now becoming a reality. A dwarf tree will provide new prospects for rain covers, bird netting, and pedestrian orchards for pick-your own operations. Our preliminary results suggest that the Gisela and Wieroot series offer some distinct advantages for size control. However, one of the overriding concerns with the Gisela rootstocks, in particular, is that excessive over cropping in the first one-two years of fruiting can result in reduced fruit size. This problem may be accentuated when self-fruitful scions such as Vandalay and Tehranivee are used. Growers and nurseries should be aware that the new clonally propagated cherry rootstocks can be more susceptible to prune dwarf virus (PDV) and Prunus necrotic ringspot virus (PNRSV). Despite the concerns, these rootstocks deserve serious consideration. Growers are welcome to visit our research orchards in Vineland to observe first-hand the performance of Hedelfingen on these rootstocks.
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Mahaleb and Wieroot 10 Fig. 3 Tree size and cumulative yield of Montmorency continue to produce the in relation to rootstock largest trees Gisela 209-1, Edabriz and 45 Wieroot 53 are the most 100 40 dwarfing, all around 18% 35 80 30 of Mahaleb. 25 60 20 All trees are showing 40 15 minimal leaning and 10 20 5 require no additional 0 0 support. There has been nominal rootstock suckering in Gisela 195-20, Gisela 6 and Mahaleb Tree size Cumulative yield Cumulative yields (precocity) have been greatest for Mahaleb, followed closely by Wieroot 10 and Gisela 6, then Wieroot 158, Wieroot 13, and Gisela 195 and Gisela 7. (Fig. 3) Wieroot 53, Edabriz and Gisela 209-1 have been the least precocious In 2003, Wieroot 72, Fig. 4 Yield and mean fruit weight of Montmorency in Mazzard, Wieroot 158 and relation to rootstock Wieroot 10 produced the largest fruit while Gisela 35 6 209-1 produced the 30 5 smallest. 25 4 In 2003, Gisela 6, Wieroot 20 3 15 10 and Wieroot 158 2 10 produced the heaviest yields 1 5 while Gisela 209-1 produced 0 0 the lightest yields (Fig. 4)
Tree size (% of Mahaleb)
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