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 The Art and Science of Pruning
We are getting to that time of year where some folks are thinking about pruning. But hold on! Before you jump in and start exuberantly cutting away at branches, let's try to go over some basics to help your approach and refine your technique. In the next few newsletters, we'll cover important aspects of pruning. In early December we will have a webinar dedicated specifically to the Art and Science of pruning, so stay tuned for more information on that. For now, dear readers, take a step back and enjoy the change in seasons and the fruits of your labors.
At the end of this newsletter, please take note of the revised Calendar of Events and the addition of Announcements section.
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Everyone loves to prune. And at the beginning of each new season, we’re all chomping at the bit, just itching to get started. In fact, this time of year I get more questions about pruning than almost anything else. However, there's more to pruning than just going out and cutting off branches or vines. There is an art and a science to pruning.
Pruning is both dwarfing and invigorating for the plant. It helps you manage tree size and shape, while maintaining a proper level of growth to ensure healthy, annual bearing. You prune to get rid of last year’s unwanted growth, dead or diseased limbs, open up the tree and restructure the canopy for better light and air penetration, encouraging good fruit bud formation, and quality fruit development. Pruning too early can lead to bad results under the wrong circumstances – since you may prune off more potential fruit, lose crop to a freeze or frost, and send the plant back into a vegetative phase. Prune too little and the crop suffers. Pruning too late can just as easily cause an imbalance and poor fruit quality by eliminating too much of last year’s reserves from this year’s growth and fruit.
Why Prune?
Pruning is fundamentally about maintaining a healthy functional plant architecture, including maintaining a proper fruit to vegetative bud ratio, fruiting branches between 2-6 years old, and an open canopy. You need to prune your trees in a manner that ensures proper limb spacing, orientation, age, and size. Too many bigger, older limbs and you end up with trees that quickly decline in terms of the productive potential. Too many smaller, younger limbs and you end up with a tree that doesn’t have enough bearing wood and low productivity. Small, weak, damaged, rotten branches will never function properly, nor will they provide the structural strength needed to carry a crop.
The ideal is a good mix of young and old, big and small, properly spaced and oriented to permit good sunlight penetration, air movement, bearing and non-bearing wood for solid annual productivity. A healthy, physiologically active tree is the goal – and an annual pruning program will ensure this. Even if, you are shooting for distressed trees in order to drive down the vigor and drive up the concentration of fruit qualities, you need to prune. Low-functioning and diseased trees will not produce fruit of any quality except poor. And by the same token being heavy-handed with the loppers will lead to trees being over-vigorous and susceptible to all kinds of insect and disease issues - not to mention out-of-sync fruiting cycles. Pruning is an art and science. If you understand the science, but use your creative side to apply it, then you may end up with an orchard that outlives you. Pruning, as in all things in life, is about balance. And balance is the secret to happiness, no matter whether it is your trees or you - hopefully both.
Pruning - Cause and Effect
• Sunlight – first and foremost plants need quality sunlight. Without light they can’t photosynthesize, support a crop, develop high quality fruit, or develop fruit buds for next year. Opening up the tree or vine with proper pruning so the sunlight can reach all areas, striking the leaves and bark optimally is critical. More than anything else we do in farming, we principally are in the business of harvesting sunlight. Adequate pruning is critical for semi-dwarf and larger trees. It was shown years ago that even in well-pruned trees, only about 30% of the canopy (the exterior 30%) gets enough sunlight. The rest is shaded to varying degrees. So simply consider this: sunlight = sugar. If you’re not photosynthesizing, you’re not growing. The sugars produced during photosynthesis help the developing fruit buds overwinter properly and grow strong next spring.
• Air Movement – second only to sunlight, you need to consider how air moves through your tree's canopy and the crop, and how pruning can help that process. Good air movement in concert with good sunlight penetration can help dry out plants after a rain or heavy dew, while helping moderate the temperature throughout the tree.
• Water and Nutrients. Pruning also helps manage the number of growing points in the plant. Each growing point requires a certain amount of resources to grow properly. Too many growing points and it dilutes the available resources to other part so the plants. Too few and the plant could grow excessively vigorous, even rank, growth with very few fruit. So before you start pruning always keep in mind the ratio of fruit to vegetative buds on the plant before making the first cut.
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