Sweet Cherry Balanced Cropping
Some Cherry Pruning Considerations and Concepts for Discussion
Dr. Gregory A. Lang, WSU/IAREC Stone Fruit Field Day
June 6, 2000
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Good pruning is a combination of tradition,
art, and science, probably
in that order.
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The introduction of new plant factors – e.g., dwarf stocks, unique
bearing habit – place more emphasis on art and science than traditional
success.
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Why prune a fruit tree? 1) Contain tree in its allotted orchard space,
2) Remove unhealthy or poorly-placed wood, 3) Ensure light distribution
through out canopy, 4) Balance the future
crop load (“resource sinks”) with the future leaf area (“resource synthesis”).
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In cherries, a significant amount of spring fruit (and shoot) growth
is dependent on stored resources (synthesized carbohydrates, applied nitrogen)
from the previous year’s growing season. Jake Gutzwiler’s research has shown that in spring, new shoots out-compete developing fruits for stored resources.
As new shoots mature, photosynthesis from leaves near fruit become more
important than stored resources for the final stages of fruit development.
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Heavy cropping removes a lot of resources from a tree; these must be
replenished via greater opportunity for resource synthesis by leaves (e.g.,
more leaves) and/or via greater resource storage by higher fertilization
(foliar, maybe ground applications).
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The new shoot growth that occurs this year
will provide: in 2000, photosynthesis mostly for self-growth and
winter storage reserves; in 2001, sites for new flower buds to form microscopically
plus photosynthesis to support direct growth of older fruiting sites; and
in 2002, actual fruiting sites plus spur leaves to support those fruit.
Thus, the current 2000 crop was determined to a large extent by the new
growth that occurred in 1998 (and pruning decisions that were made then).
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Other ongoing research – Dormant heading cuts help balance the propensity
for heavy crop loads in trees on Gisela
® rootstocks by 1) possible removal
of existing flower buds to affect this year’s crop, 2) stimulation of new
shoots for eventual resource synthesis to affect this year’s crop, and/or
3) possible inhibition of flower bud formation on year-old wood, or flower
bud abortion on older existing spurs, to affect the size of next year’s
crop.
For more information, please refer to these recent Publications:
(Available links generally refer to the abstract from the article. Access to full text of the article may require membership and/or subscription. GoodFruit Grower articles are available online for subscribers by registering at www.goodfruit.com)
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Lang, G.A. 2001. Intensive sweet cherry orchard systems - rootstocks, vigor, precocity, productivity, and management. Compact Fruit Tree 34(1):23-26.
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Whiting, M.D. and G.A. Lang. 2001. Sweet cherry photosynthesis, crop load, and fruit quality relationships. Fruit Grower News 40(11):42-46.
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Guimond, C.M, G.A. Lang, and P.K. Andrews. 1998. Timing and severity of summer pruning affects flower initiation and shoot regrowth in sweet cherry. HortScience 33:647-649.
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Lang, G.A. 1998. High density orchards and intensive crop regulation. Good Fruit Grower 49(16):45-47.
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Maib, K.M., P.K. Andrews, G.A. Lang, and K.D. Mullinix (eds). 1996. Tree Fruit Physiology: Growth and Development. Good Fruit Grower Press, Yakima. 165 pp.