Backyard Fruit Production: Part 2 – Why Pruning Matters

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As I was writing the first real installment of the Backyard Fruit Production series, I realized I should probably stop and explain a few things about pruning first.  First of all, why is pruning so important for perennial crops in general, and tree fruits in particular?

Why do we Prune?

  • To improve the Health of the Tree

Tree fruits are wonderful.  But like most perennial food crops, the biggest challenge with tree fruits is combating the host of pests and diseases they are susceptible to.  Annual crops, like those in your vegetable garden, have their own problems with pests and diseases.  But with long-lasting perennials like fruit trees, you can’t practice organic pest management techniques like crop rotation or growing under row cover.  And you can’t start fresh with new plants each year.  Fruit trees are an investment, and the best (no-spray) way to protect that investment is to improve the health of the trees you’ve got through pruning.

How does pruning improve the heath of your trees?  First, getting rid of excess branches improves airflow through the tree.  This helps keep little moist microclimates from forming where foliage is too dense.  And because most fungi and bacteria love warm, moist places, more airflow is a very good thing for your trees.  Pruning also improves sunlight penetration through the tree, and the sun’s UV rays can also help to ward off fungal infection.

Second, pruning helps prevent the spread of disease within your trees.  By pruning off diseased branches as soon as you notice them and removing them from the area around your tree, you can help prevent infections from spreading to healthy branches or to other trees.

Third, pruning minimizes entry points for pests or infection-causing bacteria and fungi.  Dead wood or open “sores” are invitations for infection, so remove all dead or damaged branches as soon as you see them.  On a similar note, remove any branches that cross or rub, to avoid creating more “sores” on your tree.  (Note: a clean, properly performed pruning cut will heal much faster, and resist infection much better than a raggedy wound).

  • To Concentrate Energy on Fruit Production

Pruning removes growth that was previously using some of the energy supplies of the tree.  When too much of a tree’s energy supply goes to support vegetative (non-fruit) growth, the tree produces small, unimpressive fruits.  Removing some of that excess vegetation causes the tree to focus its energy on fruit production, producing bigger, more usable fruits.

  • To Produce Better Fruit

I mentioned that pruning increases sunlight penetration through a tree.  Well, in addition to helping fight fungal infections, more sunlight produces sweeter fruit!  Pruning to reduce disease risk also results in healthier fruits that look better, taste better, and keep longer in storage.

  • To Make Harvesting Easier

This one’s pretty simple.  Pruning to keep most of a tree’s branches at an easily reachable height makes harvest time a whole lot easier.  One of the things that determines a tree’s height is the rootstock it’s grown on (more on rootstocks in a later post), so you’re never going to be able to get a tree grown on standard-height rootstock look like one grown on dwarfing rootstock.  But you can prune to keep the height of your tree in check, increasing the amount of fruit you can actually get to at harvest.

A note on thinning:  Thinning is intentionally removing some of the potential fruit from a tree.  Thinning is usually done either at flowering time, when the amount of potential fruit sites (flowers) first becomes visible, or at the very beginning of fruit-set, when the fruits are tiny.  The desired fruit spacing after thinning varies between fruit types, but typically tree crops are thinned to about one fruit every 5 inches.  Thinning has a number of purposes in common with pruning:

  • It improves airflow between the fruits, reducing the disease risks caused by overcrowded or touching fruit.
  • It reduces competition between fruits, so the fruits produced are larger and better quality.
  • It allows the grower to keep only the most promising fruit in a cluster, concentrating the tree’s energy on those fruits that were likely to be the best anyway.
  • It helps prevent biennial bearing patterns.

Okay, so that last point may need some explanation.  Certain fruit tree cultivars tend to bear fruit biennially – that is, they have a really heavy fruit yield one year, and then the next year’s yield is very small.  While this is fine for the tree, typically the humans tending the trees would rather see a consistent amount of fruit produced each year.  Thinning will never eliminate a tree’s biennial tendencies, if a variety is prone to it.  However, thinning heavily during bumper crop years encourages the tree to set a good amount of fruit the next year.  Thinning during sparse years should be done sparingly, if at all.

That’s it for now, stay tuned for a fruit tree pruning primer!

 

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