Ahhh, June. The rain is gone, the bugs are buzzing, and there is adequate light to bar-b-que at 9 p.m. (just when it begins to cool off). I don’t know about you, but I started wearing sunscreen in mid May; my skin always needs a little time to adjust to the “new” sun intensity. That makes me think of trees. How, you ask? Well, I’m not thinking about all the wonderful shade they provide at 3 in the afternoon. I’m thinking about how much they must suffer while being exposed to the sun all day long. Can you imagine how you would feel if you couldn’t move even an inch from sunup to sundown? Well, one time I fell asleep while sun tanning and I think I have a pretty good idea of what that feels like. Believe it or not, trees sunburn!
This malady is caused by the intense western and southern sun baking on the bark of a tree’s trunk and/or branches. Because young trees have a thin bark layer, they are predisposed to damage. Until a tree has grown large enough to shade its own trunk, they should be protected from the summer sun.
Repeated sun exposure to a trunk causes water-filled cells to heat and then burst. The bark begins to detach from the cambium layer and a canker (or wound, if you will) is formed. This damage is irreparable and makes the tree susceptible to disease and insect infestation.
In Redding, preventative care is a must! Regular irrigation and “sun screen” will help keep your trees healthy and happy during the summer months. Sun screen comes in two ways. We all have seen white-washed trunks on orchard trees. This method requires reapplication only a couple of times until the tree can protect itself. There are water-based latex paints you can use (any reflective color will do), however, there is a paint made especially for this purpose and can be found in most hardware stores. A paper wrap is also used to block the sun’s harmful rays. This is the method used in the Arboretum and Botanical Gardens at Turtle Bay. Every April the younger and already-damaged trees are wrapped with this stretchy paper and every winter the paper is removed. Although time-consuming, this is the preferred method in the Botanical Gardens because it is less “permanent” (some paint will remain on the bark years after treatment has ceased). Either method is effective in preventing irreparable damage to your young tree.
If your tree has already suffered from sunburn, you will need to clean the wound and paint or wrap the trunk for as long as is necessary. This means you may need to care for this tree in this manner for the rest of its life. Once a tree has been damaged, regular irrigation and soil amendments will help keep the tree’s defense mechanisms up so that it can ward off invaders.
For more information on the care of sun-damaged trees, please feel free to email me at: mstadther@turtlebay.org Also, I teach tree care classes two or three times a year at the Botanical Gardens. Check the calendar at turtlebay.org for upcoming classes.
Marie Stadther’s life in Coachella Valley was void of trees. In 2001, she packed up and headed north. After a drive through the majestic redwoods, she arrived in Redding, where she immersed herself in horticulture as owner of her own landscaping company and as assistant to an arborist. She is now the lead gardener for Turtle Bay’s McConnell Arboretum and Botanical Gardens. Her love of trees is a way of life, and she shares that passion with the community. Send the Tree Goddess your questions at mstadther@turtlebay.org.
