The LW Treecare Blog

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SPF for trees?

It might surprise you to learn that trees do get sunscald or sunburn and the remedy is not an SPF 30 lotion. Sunscald on trees usually happens on the south or south-west exposed bark. The bark is damaged and in severe cases can result in the death of the tree.

Historically, sunscald has been prevented by wrapping or painting the trunk of the tree.

Sunscald has been studied for many years but the science is still not conclusive. To start with, there are really two types of sunscald; one happens in winter and the other happens in summer. The one that happens in summer is sometimes called sunburn or summer sunscald to distinguish it from winter damage.

Summer sunscald happens when the bark of trees gets too hot. This usually happens in warmer climates and it usually affects young trees or young branches of older trees. The tissue in the bark gets so hot that cells start to die.

It is clear that the sudden changes in temperature cause the damage but other factors also play an important role.

Certain species of trees including birch, maple, linden (basswood), boxelder, ash, balsam fir, Douglas fir, spruce, and eastern white pine are more susceptible to sunscald.

Young bark is more susceptible than older bark which is thicker and provides better insulation for the living inner cells.

Bark thickness seems to be an important factor in determining if a tree will develop sunscald. The thicker bark found on certain species and on older stems and trunks are less likely to be damaged.

The other main contributing factor is water stress. Trees that are well hydrated during the winter months are less likely to get sunscald. This is one reason why it is critical to keep newly planted trees well watered.


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