Both deciduous and evergreen trees can suffer damage by early fall or late spring frosts. A tree's branches affected by a late spring frost may leaf out later in the spring. To determine if the branch is viable, the scratch test works well-–with your thumbnail scratch the bark away to see if it is green underneath. If it is not green, but appears dead, it can be pruned. To trim the branch, always cut outside the branch bark ridge and collar--do not cut flush with the trunk. Leaving a bark “collar” allows the tree to heal properly. Wound dressings have been shown to interfere with the natural development of callous tissues that eventually close the pruning wound. For more information, see the fact sheet:
Environmental Disorders of Woody Plants

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