#DurhamCooperativeExtension – Extension Master Gardener Volunteers of Durham County

By Jeff Kanters, NC State Extension Master Gardener^SM volunteer of Durham County

“The only true wisdom is in knowing you know nothing.” –Socrates

This is an installment in our ongoing series “The Budding Orchardist,” where Jeff Kanters, orchard team leader, shares his know-how on growing fruit.

It’s summertime, summertime, sum-sum-summertime as the song goes.

Among the many tasks the orchard team has during the growing season at Briggs Avenue Community Garden’s Teaching Orchard, the most critical for fruit trees is summer pruning. So, let’s explore the when, why, and how of that activity.

When: Proper Pruning Time in the Orchard

Whereas winter pruning is completed in January, summer pruning is completed by the summer solstice or June 21^st. We strive to start the pruning by the middle of June to complete the pruning by the 21^st of the month.

Why: Purposes of Summer Pruning Fruit Trees

While winter pruning corrects for shape, pruning the trees at peak summer manages the size of the tree by removing much of the accumulated sugars built from photosynthesis that are still held in the canopy of the trees. This is important because starting in July, the trees–having maxed out their summer growth–begin to move the sugars in their canopies down to the roots for storage during the upcoming winter. By reducing the amount of sugars moved to the roots at the right time, we reduce the overall vigor of the tree. With repeated summer pruning, we can keep the tree at a much smaller size for ease of future maintenance and fruit harvest. The orchard team of Master Gardener volunteers aims to maintain the fruit trees to a height of between 8 and 10 feet.

How: Proper Pruning Techniques for Fruit Trees

We prune out roughly two thirds of the current season’s canopy growth. This includes dead or diseased limbs, crossing limbs, limbs growing inward, downward or upward so the center of the tree is opened. We prune to outward facing buds to push a potential limb out from the center of the tree to more sunlight. This is an aggressive pruning, but our aim is to secure the long-term health of the tree. Trees that are overgrown in size are more prone to diseases, limbs breaking from the weight of excess fruit that is smaller and of lesser quality, and a hampered ability to manage and care for the tree. If fruit trees are left unpruned, they may reach heights of 20 to 25 feet tall, well beyond the reach of many homeowners and small orchards.

Summer pruned orchard rows at the Briggs Avenue Community Garden’s Teaching Orchard. Note the manageable size we keep the fruit trees for easy maintenance. (Image credit: Jeff Kanters)

In addition to size, shape matters. We prune our peaches and plums to an open bowl shape and our apples and pears to a central leader or Christmas tree shape. Both keep the inside of the tree open to maximize good air circulation, photosynthesis, healthy and higher quality fruit production, and ease of harvesting.

(Left to right) Summer pruned peach tree showing the open center bowl shape maintained for stone fruit trees and summer pruned pear tree showing the central leader or Christmas tree shape. This promotes is good air-circulation, which reduces disease pressure. (Image credit: Jeff Kanters)

Summer pruning is a necessity to ensure future success in achieving manageable-sized healthy trees that produce delicious fruit. And of course, all this advice applies to all fruit trees whether it be those in a small teaching orchard or one just outside your back door.

Resources and Additional Information

Below you will find references on growing and pruning fruit trees.

Fruit Trees (General)

Grow a Little Fruit Tree: Simple Pruning Techniques for Small Space, Easy Harvest Fruit Trees; Dec 30,2014; Ann Ralph
North Carolina Production Guide for Smaller Orchard Plantings: https://content.ces.ncsu.edu/north-carolina-production-guide-for-smaller-orchard-plantings
North Carolina Extension Gardner Handbook, Chapter 15 Tree Fruits and Nuts: https://content.ces.ncsu.edu/extension-gardener-handbook/15-tree-fruit-and-nuts

Fruit Tree Pruning Basics

Article Short Link https://wp.me/p2nIr1-4OV

by Andrea Laine, EMGV

You know you’re a serious gardener when you get excited about preparing a sample for the NCSU Plant Disease and Insect Clinic. I just wish I had engaged this problem-solving staff sooner and I hope you will learn from my experience.

Over the last three or four years, the mature evergreen azaleas in my landscape – of which there were many – began to succumb to a sudden dieback. Where there was once dark green glossy leaves and abundant flowering, seemingly overnight a swath of vertical branches would turn brown and die. I was alarmed, but knew not what to do. So, I did next to nothing: I trimmed out the crispy parts and hoped for the best.

I am ashamed to admit this experience was after my master gardener training. In training we certainly learned about the services provided by the Plant Disease and Insect Clinic, but either I didn’t think my plant problem was important enough to bother someone at NC State, or I was too lazy to prepare a sample. Probably a little of both.

*The photo on the left was taken in 2013. The one on the right was taken summer 2019. It’s heartbreaking to see how robust the azaleas once were and are no more. Photos by A. Laine.*

Inspired to act

Fast forward to this summer when two things happened that inspired me to act. First, the mysterious dieback attacked a stand of azaleas that are a key structural element in the design of my landscape (see photos above). And secondly, I noticed the exact symptoms on a few azaleas in a Durham neighborhood far from my own. The problem no longer belonged just to me; I resolved to seek a diagnosis on behalf of all of us.

My first step was to collect a soil sample from the vicinity of the azalea with the most recent dieback. The results showed that the soil pH was too high – 6.2 – where azaleas prefer a number between 4.7 and 5.3. Phosphorus was high and potassium was a little low. While all that is not a great situation for these acid-loving plants, it did not explain the sudden dieback. I needed to delve deeper.

I decided to access the NCSU Plant Disease and Insect Clinic. (You’ll find a direct link to it on the right side of this blog’s homepage as well as in the list of resources below.) I dug up a smaller azalea that had browned out a year or so earlier, left a good bit of the roots and soil intact and plunked it into a double plastic bag. Back indoors, I downloaded a submission form from the Clinic’s website, filled it out to the best of my ability and brought it and the sample to the master gardener office where I enlisted the help of our County Ag Agent Dr. Ashley Troth. Ashley submitted the sample on my behalf and we included digital images of the affected plants in my landscape. The more information a client can provide, the better will be the diagnosis and recommendations.

*I had decided to remove these small, scraggly azaleas from the landscape anyway. So, I used half of one as my sample to the Plant Disease and Insect Clinic. Photo by A. Laine.*

A diagnosis

A week later the diagnosis was in: Symptoms are typical of Phomopsis dieback, a fungus disease. “The disease can be very serious if the fungus moves into larger branches and the base of the plant. This dieback was found down into the base of the plant submitted,” wrote Shawn Butler, an ornamentals diagnostician. “Presence of this disease,” he continued, “often is an indicator of stressed or injured plants. Photos show that there is probably a problem in the root zones of these plants. No root rot pathogens were isolated from these roots. If the plants have been water-stressed in the past, then that might be the primary problem.”

He also sent a root sample out to check for presence of damaging nematode populations. Some parasitic nematodes were found but populations were not high enough to cause damage.

A new pledge

I will take away at least two lessons from this experience (and I hope you do, too). The first is to seek help sooner, and the second is to not ignore long-established shrubbery. (These azaleas were planted at least 20 years ago.) The plants I inherited with my landscape deserve tender-loving-care equal to that which I provide to the plants I personally select for the landscape.