2.5 Preventing Sunscald
Phone calls come in periodically indicating that chestnut blight has emerged in an orchard. I will go to the orchard and usually find a canker similar to chestnut blight on the base of the tree that has no apparent chestnut blight. It is a problem called sunscald or “southwest disease”.
As was mentioned above, young transplants and thin-barked trees, are susceptible to an injury called "sunscald" during the winter and early spring. Chestnuts have big problems with sunscald in the midwest. In California, the scald occurs in the summer but in Michigan we believe the scald occurs in the winter and early spring. The surface temperature of trees is elevated above that of the surrounding air by the absorption of sunlight. This rise in surface temperature occurs long enough to make cells in the bark active and thus vulnerable to injury during the sudden nighttime temperature drop. Growers need to paint their trees with a white latex paint diluted 50% with water. Paint high enough to protect all parts of the trunk (up to and beyond the crotch). The paint should be an indoor, cheap white latex diluted with water. This reduces the amound of preservatives in the paint that may damage the tree.
Don’t Forget About Your Tree Guards!
Don’t forget to take off and adjust the white tree guards. These tree guards work well to prevent physical damage of the main stems caused by either mammals or equipment. But they should be adjusted at least twice each growing season. They do not expand on their own. Here you can see the spiral effect on the trunk of a tree this summer.
You can even see the protrusion of the bark through the tree guard holes.