Carrot-Top Syndrome

An unfortunate characteristic of pines, especially the eastern white pine (Pinus strobus), is that after pruning or shearing, vigorous terminal growth resumes but lateral growth remains suppressed. This results in a tree that bears a striking resemblance to a carrot with the greens still attached. Hence, the Carrot-Top Syndrome.

The white pine is one of the most commonly planted conifers in the United States. This species of pine is native throughout much of the eastern US and is an extremely fast growing tree that makes a good ornamental when planted on the right place with room to grow.

Thus, when these pines are used for Christmas trees, some people simply cut off the top end of such a tree. This practice will also result in the Carrot-Top Syndrome.

Biologists are not sure why Carrot-Top Syndrome occurs almost exclusively in white pines and not other trees. It may simply be related to vigor of white pines.