Dallas Morning News - August 28, 2019

Wrapping Tree Trunks – Bad Idea

As the hot summer sun beats down on the south and west sides of exposed tree trunks, there can be some damage. Bark can overheat, sunburn and crack. Unfortunately there is some bad advice out there about what to do to prevent this damage. Wrapping the trunks of new red oaks, maples, Chinese pistachios and other thin bark trees with paper tree wrap is not the proper answer.

Wrapping trunks sets up an environment for disease and pests to move into

It is mistakenly said that covering trunks with wrap will prevent insects (including borers), diseases and sunburn. Truth is the wrapping will actually provide better environment for the diseases to get started and for the insect pests to set up shop. It also causes an artificial condition similar to your skin when a bandage is left on too long and more damage can be done when the wrapping is removed and the bark re-exposed to sunlight.

One simple thing that would help solve sunburn issues is for the growers to put a red dot on the north side of the tree so the garden center and then the homeowner or developer could keep the same sunlight orientation when the tree is planted.

Then painting trees with a whitewash has a far greater impact on protecting from sunlight and also low temperatures than wrapping or piling soil around the trunks - which some folks still recommend. Being too deep in mulch and soil is the most common cause of stress in trees and can lead to sunburn and pest problems. So – get your trees that are too deep in the ground uncovered so the flares are dramatically exposed.

Be sure the root flare is exposed

Latex paint is safe to apply

If heavy pruning of your trees has exposed the trunk and branches to sunshine, the painting can be done, but a better approach is to just avoid overpruning.

Gardeners and growers have traditionally used a lime-based whitewash made from hydrated lime, water and oil – but that's caustic and really unnecessary.

The best coating is a water- based, white latex paint. Some growers find it beneficial to put repellents and pesticides in the paint but that's also unnecessary. Diluting the paint at least 50% with water is cost effective and works well. White is the color commonly used but using a color that matches the bark is better looking and works as well. Again mix it 50-50 with water to make a wash.

Water-based white latex paint can be diluted, and linseed or horticultural oil added

Latex paint thinned with water alone works nicely

Adding oil helps the wash stick. Linseed oil is the traditional choice, but horticultural oils will also work. I usually skip this step. Just paint and water works nicely, is easier and less messy.

For additional information on this subject see TexasOrganicResearchCenter.org and the following link:
https://fruitgrowersnews.com/article/painting-tree-trunks-protects-against-rodents-borers/

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