Citrus tree trunks are painted white to reflect sunlight off the tree’s bark in the winter season. This prevents the tree’s sap from entering a thaw and freeze cycle that might damage the tree’s tissues. The reflective paint also keeps citrus trees from becoming sunburnt in the summer.
Solved! Why Are Trees Painted White?
By Steph Coelho | Published Jan 10, 2023 6:54 PM
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Q: Driving home from work the other day, I noticed several trees on my street painted white. Why paint tree trunks white? What does white paint on trees mean?
A: While bright orange or red tree markings might mean a tree is destined for removal, white paint on trees means something entirely different. So, why paint trees white? Although the crisp, bright white may look pretty, the paint isn’t for aesthetics. Those tree trunks around town are covered in white paint to protect them from the elements. And that’s important, since trees are attractive parts of the landscape and offer shade for homes and outdoor living areas in summer.
Like plastic, paper, or aluminum tree guards, white paint on trees offers protection from the sun, harsh weather, and pests. Read on to learn more about why people paint the bottom of trees white, and why choosing the right paint is key.
Painting the bark on young trees helps to prevent sunscald.
Like people, plant life is vulnerable to damage from the sun. Deciduous trees, which shed their leaves at the end of the growing season, are particularly vulnerable to sunscald during the winter months. The branches devoid of leaves offer no protection from the hot rays of the sun. And in areas with very hot climates, trees may be prone to sunscald year-round.
The white paint on the trunks helps reflect sunlight and prevents the tree’s bark from getting too much sun. In the winter, an overabundance of sunlight can cause thawing of critical tissues under the bark. They then can refreeze when temperatures drop, leading to trunk cracks and fissures. These wounds are perfect entry points for pests and diseases.
Thick latex paint can help protect trees from the elements.
Damage from sudden thaws and freezes can leave trees, especially those bearing fruit, in a vulnerable state. In cases of severe injury, the damage can be fatal. Applying heavy latex paint (or a specially designed formula such as this highly rated option available at Amazon) to a tree trunk can help protect trees from harsh winter weather.
The University of Tennessee Agricultural Extension Service recommends using interior-grade latex paint to whitewash tree trunks and avoiding toxic oil-based paints. It’s also best to use tree trunk painting only on trees older than 2 years. For younger trees, opt for plastic or aluminum guards instead of paint.
The ideal time for painting bark on trees is at the tail end of fall on a sunny day to allow enough time for proper drying. Before applying the paint, dilute it with an equal amount of water. If the first coat appears to be too thin, add a second coat. You can apply the paint using brushes, sponges, or cloth rags. You also can spray paint a tree white, but likely will need to give it two coats.
Tree trunk painting also deters pest infestations.
Painting a tree trunk with white paint prevents pests from gaining access through various small openings. Protecting trees from sunscald using white paint also prevents these cracks from forming in the first place.
When painting a tree trunk white, make sure to paint up to at least 18 inches above the ground. You can even paint up to the point where the first major branches join the trunk for additional protection. When painting, it is essential to cover the trunk thoroughly. Any bare spots might represent access points for hungry pests.
Latex paint is ideal because it won’t crack as it expands, which might again leave your tree vulnerable to pest infestations. To provide continual protection, reapply whitewash annually.
Should You Paint Your Citrus Trees White?
Consider painting, or “whitewashing”, your citrus trees if you live in an area that gets cold, dry, and sunny winters. The white paint will help protect the tree during extreme heat in the summer, and the freeze and thaw cycles in the winter.
To determine if you should paint your citrus tree trunks white, it’s helpful to know a bit about what happens to citrus trees during freeze and thaw cycles.
Citrus tree painting is most common in desert areas like Arizona or in parts of California that have a higher elevation, where the temperature difference between day and night is enough to throw off the tree’s sense of dormancy.
To better see how warm days and cold nights can damage a citrus tree, think of how you use hoses during the winter. During freezing weather, hoses generally need to be drained of all water. If there’s water left inside, the hose will expand and rupture the hose from the inside-out. The same can happen with citrus trees.
When it’s warm, citrus tree sap normally moves up and down its tissues. However, during freezing weather, the flowing sap will become stuck from the cold. It also expands as it freezes, which bursts plant cells and tissues.
Because of this, the citrus tree could then crack or split, which exposes the tree and increases the risk of pests or disease from bacteria or fungus.
Trees can also become dehydrated and stressed by the lack of flowing sap, as the cold and dormant roots won’t provide water or nutrients to the active tissues.
This stress from infection or dehydration can stunt the citrus tree’s growth or fruit production for all of the next growing season and beyond.
So, where does white paint come in?
White paint reflects the strong winter sunlight off of the citrus tree’s trunk and prevents the tree from warming and waking up from its dormancy. By keeping the tree’s temperature lower during the warm days, the freezing nights aren’t as drastic. This prevents the tree from going through extreme internal temperature swings and protects the tissues from bursting.
Because of this, the tree remains stable and in a sort of stasis throughout the dormant, winter season.
What Else Does White Paint Protect a Citrus Tree From?
Whitewashing a citrus tree when it is young also protects the thin bark from sunscald damage, which is caused by the strong sun beating directly onto the tree bark without the protection of foliage or other shade. It’s essentially a sunburn for trees.
Also, painting the trunk white adds another layer to the thin bark that can help with light physical damage, like something hitting or scraping the trunk.
Some orchardists also rely on the painted bark to help them spot borers, as their sawdust trails show up more easily on the white paint than they do on the plain bark of an unpainted tree.
Is Paint Bad for Citrus Trees?
The paints used by gardeners or orchardists are usually a lime-based whitewash or a latex-based paint, which don’t harm the tree, although there are drawbacks to the latex paint (more on this below).
The white paint is applied to the outside of the bark, which is itself a shield or barrier for the tree’s inner tissues, so there’s little to no absorption in the tree.
However, not all paint is safe for use on trees. Oil-based, enamel, semi-gloss paints, and paint primer should never be used, as these penetrate and stain the bark of the tree.
How to Paint Fruit Tree Trunks
Applying white paint to the trunks of fruit trees aids in repelling fruit boring insects. According to the Missouri extension service, painting the trunks of the fruit trees in early spring, prior to any leaf growth, will repel certain species of moths and grub larvae from attacking fruit trees. While painting the trunks is effective, it is only part of a maintenance to the tree that must be performed. Healthy fruit trees are less likely to be attacked by trunk borers than trees that are less cared for and maintained.
Wear the gloves on your hands and remove all weeds and extraneous plant growth from around the fruit tree. In most all cases, the soil from the trunk area and out to the drip line of the fruit tree should be kept relatively weed-free. Excess plant growth around the base of any fruit tree may create unwanted competition for moisture and nutrients. These types of conditions may cause an unhealthy fruit tree.
- Applying white paint to the trunks of fruit trees aids in repelling fruit boring insects.
- According to the Missouri extension service, painting the trunks of the fruit trees in early spring, prior to any leaf growth, will repel certain species of moths and grub larvae from attacking fruit trees.
Place all dead limbs and removed weeds from the fruit tree to a compost pile. The compost pile must be located a distance from the growing area because some insects may migrate back to the fruit tree orchard.
Apply a white latex interior paint to the trunk of the fruit tree. Paint the trunk using the paintbrush from the base, at the soil line, up to the first set of lateral limbs.
Inspect the trunk one week later. Apply another coat if the paint is washing or peeling from the trunk. Any small holes that are appearing from under the new application of paint must be thoroughly inspected. They may represent an infestation of other small grubs or larval tree borers.
- Place all dead limbs and removed weeds from the fruit tree to a compost pile.
- Apply another coat if the paint is washing or peeling from the trunk.
Consult your local agricultural extension service for any specific insecticide treatments if the infestation is too great. Exercise caution whenever applying any chemical to your garden and trees because beneficial insects may also be harmed.
Remove all leaves and dead limbs from the base of all fruit trees. Allowing deadwood and leaves around the base of the fruit tree will encourage insects to inhabit the area.
Keep children and animals from any area that has been treated with a chemical.
Follow the manufacturer’s labeling when applying any chemical, and keep all runoff from any aquatic areas.
