The Budding Orchardist: There is No Off-Season

On By durhammastergardenersIn Uncategorized

The Third Installment in the Series “The Budding Orchardist”

By Jeff Kanters, Master GardenerSM Volunteer

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

(Image credit: Jeff Kanters)

After the long, hot, and drought-ridden summer of 2022, mid-October and November ushered in cooler weather along with shortening days. With these seasonal changes, the orchard trees, having stopped their robust vegetative growth, began to harden off and dropped their leaves through December. During this time, sugars once built and maintained in the trees’ leaf canopies via photosynthesis were transported down to the roots to be stored over the cold months ahead.

Preparations began in November to ready the trees for cold dormant-season management. Fruit tree care during the fall and winter seasons is as vital as it is in the spring and summer. Our team undertook the following to ensure future successes in the orchard.

• Painting the Trunks of Young Fruit Trees Before Winter

Trunk of fruit trees painted with white latex paint which helps prevent unwanted damage and subsequent problems. (Image credit: Jeff Kanters)

In early November all fruit trees were painted with a 1:1 dilution (one part water, one part paint) of white water-based (latex) paint along their trunks from the ground up to the first scaffold limbs. Important Note: Do NOT use OIL-based paint, as OIL-based paint is TOXIC to the trees! We did this for one main reason, and we get many questions about this.

The white latex paint reflects the sun’s rays and discourages large temperature swings to the bark’s surface. An extreme rise in heat of bark along the south-facing lower trunk can cause expansion and cracking when the daytime and nighttime ambient or air temperatures are at or below freezing. The cracking and damage to the trunk from temperature extremes opens the tree up to diseases and insects.

• Winter Pruning of Young Fruit Trees

After painting the trees, we scheduled winter pruning. Research has shown that the most optimal time to winter prune trees in the piedmont of North Carolina is between late December and early March, with February being the optimum month. There are fewer insects and diseases present, and the trees are dormant.

Winter pruning allows better visualization of the branching structure and the identification of diseased or damaged limbs. Also, by this time all the trees’ excess food (i.e. carbohydrates) is now stored in the roots, so pruning during dormancy does not decrease the available food stores of the trees when spring arrives.

While some root stocks may have a dwarfing influence on the top above-ground growth of some trees such as apples, this is not true of other types of fruit trees like peaches and plums. If you want to keep your fruit tree at a reasonable size for managing and harvesting fruit most easily, annual winter pruning is essential.

Neglecting annual training and pruning of fruit trees results in poor shape development, less quality fruit, greater disease susceptibility, and shortened life span of the tree.

Key fruit tree pruning priorities to maintain health and productivity of the tree are

  1. Remove all dead, dying, and diseased limbs.
  2. Remove limbs that crossover which can rub together causing damage to limbs and harboring disease.
  3. Remove limbs that grow downward or straight up.
  4. Increase sunlight penetration into canopy.
  5. Increase air flow in canopy and reduce fungal disease.
  6. Increase fruit production.
  7. Develop strong 45-degree angles on limbs to support fruit load.
  8. Maintain tree size (5 to 10 feet is the ideal size for the home orchard in terms of accessibility).

Important Note: Structurally, pome fruits (apples and pears) are pruned as a central-leader, Christmas- tree-like shape; stone fruits (plums and peaches) are pruned as an open-vase, bowl-shaped, multiple trunk form.

Form of plum tree (Prunus sp.) before winter pruning. (Image credit: Jeff Kanters)
Same plum tree (Prunus sp.) after winter pruning. Note the open vase-like shape. (Image credit: Jeff Kanters)

Key Pruning Equipment For Small Fruit Trees

A line-up of some of the fruit grower’s most important tools. (Image credit: J. Kanters)
  1. Lysol® disinfectant spray – Critical to ensure that the pruning tools are kept disinfected between pruning cuts to avoid the spread of disease. You can also spray tools with a 70-90% concentration of rubbing alcohol or 10:1 diluted bleach. The rule we apply is that if a tree appears healthy, then spray tool once before starting to prune and then spray again after completing the pruning of the entire tree. If, on the other hand, you have a tree with damage and potential disease on a particular branch you select to prune out, sterilize the pruning tool before and immediately after the pruning cut to avoid spreading disease to other healthy branches or limbs on the same tree you plan to prune next.
  2. Handheld bypass pruning shears – for pruning small branches up to ½ inch in diameter. Attempts to cut larger branches with pruning shears often results in torn, jagged pruning cuts and may damage the shears.1 (See note below for more information on bypass vs. anvil-action tools).
  3. Compact pruning tool blade sharpener – Very handy in keeping the blades of shears and loppers sharpened for clean prune cuts.
  4. Bypass pruning lopper – for pruning larger branches between ½ inch up to 1 ¾ inches in diameter.
  5. Pruning saw – for pruning large branches and limbs greater than 1¾ inches in diameter. Pruning saws are unique in that the blade teeth are oriented in alternating fashion forward and backward along the saw blade, thus allowing you to cut both on the forward push and the backward pull of the saw. Many shapes and sizes are available, from compact folding saws to straight fixed blades.

• Dormant Spraying of Young Fruit Trees

As soon as possible after the trees are winter pruned, we dormant spray the entire tree with horticultural oil and fungicide. This treatment focus is preventative spraying before symptoms are observed. After pruning, the tree structure is smaller and less spray is needed to cover the tree. Also, the spray application covers pruning wounds adding further protection from diseases.

The horticultural oil typically kills overwintering aphids, spider mites, scale, and eggs as they are hatching and before populations take off in warmer weather. The fungicide kills overwintering fungal spores to suppress development of rusts, fire blight, and peach leaf curl diseases. We opted to use Neem horticultural oil as the base oil.

We are testing the use of a liquid copper-based fungicide that can be mixed with the Neem oil and applied at the same time to the trees. We follow the manufacturer label directions on mixing and dilution in the spray pump spray tank. We wear rubber gloves, face masks, and safety goggles when spraying the trees, along with long sleeve shirts and pants.

Important Note: Keep sprayers dedicated to the sprays applied. Do NOT use one sprayer for different types of spraying. For instance, commercial growers have a specific sprayer for herbicide control and another sprayer for disease and insect control. We label our sprayers with waterproof markers designating their specific use. Be careful not to use more spray solution than needed.

The timing of spraying is the tricky part. By late February temperatures are starting to moderate more in the Piedmont. To maximize the effectiveness of the spraying, ambient air temperatures should be above 40 degrees Fahrenheit. Second, rainfall is not good within a 24 to 48-hour period after spraying as the effectiveness of spraying is considerably lessoned. As you can imagine, this task is easier said than done, given the fluctuating late-winter to early-spring temperatures and sporadic rains. We keep a close eye on both temperature and precipitation forecasts to optimize the effectiveness of the winter spray program. We strive to spray before too much bud swelling and break on the trees.

Important Note: To protect our beneficial insects, we strive to conduct dormant spraying before blooming and pollinators are visiting. Any subsequent spraying during the growing season is timed after blooming and when pollinators are not active. More on growing season spraying pros and cons the next installment.

The saga continues as the young trees awaken from dormancy and their growth resumes in March through the summer months. Join me looking ahead as we face summer disease and insect pest challenges on the orchard trees. Stay tuned.

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Notes

1–A few notes on bypass vs. anvil pruning shears and loppers. We strongly encourage the use of bypass shears and loppers rather than anvil types. The bypass types are essentially two blades that make a clean cut. The anvil shears and loppers crush the branch stem and cause more jagged, less clean cut that may open the tree up for disease.

Bypass pruners (left) work much like scissors and make cleaner cuts while anvil pruners (right) tend to crush plant material. (Image credit: Barbara H. Smith, HGIC Clemson Extension)

Resources and Additional Information

Fruit Trees General:

Fruit Tree Pruning Basics:

Winter/Early Fruit Tree Spraying:

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