What is the Apical Bud?

I would like to start this article with a riddle: 

When I pull a cart I go real slow, but with "Au" instead of "O" I'll decide how long a branch will grow. What am I?

Keep reading to find the answer to this riddle.

The apical bud on a plant is the bud at the very tip. You might be thinking, "What does this have to do with fruit trees?" Well, understanding this part of a fruit tree's anatomy is very important and knowing more about it could make the difference between a bountiful harvest and your fruit trees not producing anything.

In this blog, the apical bud is also refereed to as the terminal bud, or the bud that terminates (ends) the branch. In apple trees, the dormant, apical bud is where the trees is storing microscopic flower parts that will emerge in spring. These flowers, once pollinated, will become fruit. If you prune off the apical bud, you will not have any apples.

In stone fruit. the axillary buds, also know as lateral buds will bear fruit, but leaving the apical bud intact will result in a leggy tree at risk of multiple branch failures under the heavy weight of the fruit.

The Apical bud is responsible for elongation. This means that it grows at a faster rate than the lateral buds. The apical bud produces a hormone that it sends "down stream", through the phloem, to the other buds. This hormone, called Auxin suppresses the growth of the other buds on a branch. 

Did you catch the answer to the riddle above? When an Oxen pulls a cart, it goes real slow, but if you spell Oxen with an "AU" instead of "O", Auxin will decide how long a branch will grow.

Ok, so it's not perfect, but you get the gist.

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So now you know what the apical bud is, how it applies to apples and stone fruit, and how this bud affects a plant... but wait, there's more!

What happens to a plant when the apical bud is pruned out?

Have you ever pinched back your tomato plants or houseplants that are getting too leggy? When you pinch back a plant you are removing the apical bud, which temporarily removes the hormonal affects of the apical bud. The result is that your plant will fill out and become more "bushy".

I like to use a business as an example. When the board of directors decides to oust the CEO of a company, what happens? The CFO, COO, and the CMO all start competing for the CEO position. This is exactly what a plant will do. The lateral buds closest to the pruning cut will all start to elongate and begin producing Auxin.

When referring to trees, we don't pinch them back because they are woody and you would need some pretty tough finger nails to pinch back a fruit tree branch. We use the term tipping which can be done with a sharp pair of pruning shears. When you tip back you fruit trees, they will respond like your tomatoes and send out several new branches at each cut.

Tipping is a great way to help young fruit trees to fill in faster. In the summer, after the new branches have hardened off, you can lightly tip back each apical bud on your fruit tree, and if there is enough time left in the season, it will send out another flush of growth. It's important to do this early enough in the season, so the newest flush has time to harden off again before the cold temperatures in the fall.

Summer Pruning Fruit Trees

Tipping fruit trees is also how you can keep a tree from getting too tall. No one wants to rent a boom lift every time you want to harvest apples. You can learn more about maintenance pruning, and how to keep you fruit trees at any desired height by reading Lesson 7 in our free 9 part fruit tree pruning course.

I mentioned this earlier, but it bears repeating. When pruning stone fruit, it is imperative that you aggressively tip back each and every branch. This will accomplish two things. First, tipping back branches will remove several lateral buds and lighten the fruit load so that your branches don't break under all that weight. Second, tipping branches will stimulate new branches that will become productive the following season. Stone fruit produce fruit on last year's new growth.

For more information about stone fruit pruning follow these links:

How to Prune Peach Trees

How to Prune Apricot Trees

How to Prune Sweet Cherry Trees

The opposite is true when referring to Pome fruit. The apical bud is where the fruiting occurs. This doesn't mean that you can't tip back your Pome fruit, you just need to know the difference between a water sprout and a spur.

For more information about pruning Pome fruit follow these links:

How to Prune Apple Trees

How to Prune Pear Trees

Thanks for reading! If you would like to learn more about the care and pruning of fruit trees, please browse our 100+ fruit tree articles here, join our Backyard Fruit Growers Facebook Group, and take our free Fruit Tree Pruning Course. Also, please subscribe to our Fruit Pruning YouTube Channel.