Good to Know: Sleeping Eye Cherries

As sweet cherry growers around the world adopt higher density, more efficient orchard systems, they face increased financial burdens from orchard establishment. Most new cultivars and rootstocks have royalty fees, and quality nursery stock can cost more than $10 per tree. Assessments of the costs of establishing a high density sweet cherry orchard and forecasts of return on investment and breakeven price highlight the importance of tree costs in orchard profitability. As a result, there is interest in novel planting strategies to reduce establishment costs and improve profitability. The apple industry has experimented with planting bench grafts and sleeping eyes as less expensive alternatives to standard nursery trees. However, to date, no research has investigated the potential for such planting strategies in sweet cherry.

We initiated an investigation of the potential for adopting a sleeping eye planting system for sweet cherry, comparing tree survival and growth with standard nursery trees. Sleeping eyes are fall budded in the nursery and then dug and planted in the orchard the following spring. Nursery trees are fall budded but grown in the nursery for a year and dug the following fall, then planted in the orchard in the spring.

We utilized three rootstocks (Mazzard, MxM.60, and Gisela 6) and chip-budded (single bud) three cultivars (Bing, Chelan, and Tieton) on each rootstock genotype for a total of nine scion/rootstock combinations. The same person performed all budding in the first week of ­September 2005, at six to eight inches above the soil surface. To study the role of the common virus Prune dwarf virus on tree survival and growth, we also budded half of the tree with virus-free bud wood and half with virus-infected bud wood. One hundred buds were placed for each combination, creating a total of 1,800 trees (two planting systems, two virus statuses, three rootstocks, and three cultivars with ten five-tree ­replicates).

The sleeping eye trees were headed to about two inches above the dormant bud, harvested in March 2006, and shipped to the test orchard site at Washington State University’s Roza experimental farm in Prosser. Each tree was supported with a bamboo stake and plastic tree guard. The other half of the trees remained in place in the nursery row to complete the standard 18-month growth cycle as nursery trees.

Trees were trained similarly at both locations until late July when sleeping-eye trees were headed (at about 48 inches) to promote lateral branching. Nursery trees were headed only at harvest (at about 60 inches) for convenience in storage and shipping. Nursery trees were dug the first week of November 2006, and stored until April 2007, when they were planted in ten replications of five trees in an orchard immediately adjacent to the sleeping-eye trees that were established the previous spring. What follows is a preliminary assessment of tree survival and growth.

Tree survival

Overall tree survival after year one (in nursery for nursery trees and in orchard for sleeping-eye trees) was high for both systems but greater for nursery trees (87%) than sleeping-eye trees (76%). Tree survival was greatest for virus-free, nursery trees (94%) and lowest for virus-infected, sleeping-eye trees (71%). Among the cultivars tested, survival was lowest for Tieton (78%), and highest for Chelan (86%). Bing was intermediate. Among the rootstocks, MxM.60 exhibited the lowest tree survival rate (78%), and G.6 and Mazzard were similar (84%). We did observe a range of about 38% among the various combinations of planting systems, virus statuses, and genotypes. The treatment with the lowest survival was virus-infected Bing sleeping eye on MxM.60 at 60%, whereas Chelan on G.6 that were nursery, virus-free trees had the highest survival at 98%. Overall, the survivability data do not indicate a clear best choice among cultivars or rootstocks but do suggest that virus-free bud wood is important to use in creating sleeping-eye trees. Bing exhibited particularly poor survival when virus-infected bud wood was used. Average survival of Bing as a sleeping eye on all rootstocks was 85% using virus-free bud wood but 65% using virus-infected bud wood. It is important to remember also that the overall survival rate of 76% for sleeping-eye trees represents an actual reduction of 24% compared with nursery trees because trees that perish in the nursery are culled and not delivered. Therefore, the potential economic benefits of planting lower cost, sleeping-eye trees might be offset by the need to replace those trees.

Tree growth

We found that final tree height was about 8% less for trees made from virus-infected bud wood and that sleeping-eye trees were about 10% less vigorous than nursery trees. However, since trees were retrained with heading cuts in the beginning of the second year, there may not be any advantage to more vigorous growth in year one. Total root dry weight (indicative of root growth) of nursery trees was about 10% greater than that from sleeping-eye trees after year one. In addition, nursery trees had 40% higher total shoot dry weight after year one than sleeping-eye trees.

These differences may have been
due to sleeping-eye trees experiencing transplant shock, sleeping-eye trees being headed in year one, or cultural practices between the nursery and the orchard site. However, after year two (second year in place for sleeping-eye trees and first year in orchard for nursery trees), sleeping eye trees exhibited more than twice the growth of nursery trees. This growth is future fruiting wood that may improve system precocity in third and fourth leaf versus nursery trees.

Key considerations

Sleeping-eye trees

• Lower costs of establishment ­versus greater tree losses

• Increased demand for management and care in first year versus the potential to implement specific training strategy in first ­(normally nursery) year

• Strong growth in second year because of no transplant stress

• Improved precocity?

Nursery trees

• Higher establishment costs versus greater tree survival

• Nursery assumes risk of poor bud take

• Better growth in nursery

• Poorer growth in first orchard year than sleeping eye trees

• Precocity?

Further reading

Whiting, M.D., Lang, G., and Ophardt, D. 2005. Rootstock and training system affect sweet cherry growth, yield, and fruit quality. HortScience 40(3):582-586.

Warner, G. 1995. "Orchard-grown trees are cheaper, but riskier." Good Fruit Grower, Yakima, Wash. www.goodfruit. com/subscriber/archive/1995/44other.html.

Warner, G. 1996. "The pros and cons of a do-it-yourself nursery." Good Fruit Grower, Yakima, Wash. www.goodfruit. com/subscriber/archive/Feb_1-96/special 2.html.

Warner, G. 1998. "Price of sleeping eyes may be sleepless nights." Good Fruit Grower, Yakima, Wash. www.goodfruit. com/subscriber/archive/June98/feature7.
html.

Warner, G. 2006a. "Feathered trees v. sleeping eyes." Good Fruit Grower. Vol. 57 no. 7. p 35. Yakima, Wash.

Warner, G. 2006b. "Grower finds trees a better bet than bench grafts." Good Fruit Grower. Vol. 57 no. 7. p 17. Yakima, Wash.

Warner, G. 2006c. "Sleeping eyes cut initial costs." Good Fruit Grower. Vol. 57 no. 7. p 14. Yakima, Wash.

Witney, G. 1998. "Practical Grower: Growers may save on nursery costs, but…." Good Fruit Grower, Yakima, Wash. goodfruit.com/subscriber/archive/ Dec-98/column3.html.