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Tree trivia

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Do you know why some trees withstand windstorms better than others? What a Crotch Cut is? Why you should be wary of a boulevard of dogwoods? Consult this handy trivia guide and impress your friends with your esoteric knowledge of trees and their terminology.

Cankerworms Innocuously known as inchworms, these invaders are actually quite destructive. They climb trees to lay their eggs, and the voracious larvae eat the leaves. Enough larvae can defoliate an entire tree, like stoners at an all-you-can-eat buffet. The larvae then parachute from the treetops on strands of silk, only to climb the tree again. They're not very smart.

Some trees in Durham have been fitted with sticky bellybands—similar to flypaper—to catch the worms on their migration, during which they become mired in these belts of death.

Cankerworms invaded the Triangle last year, and it wasn't uncommon to see your friends walking down the street with squished worms in their hair.

Cantilever When all the branches are trimmed from one side of a tree, making it unbalanced and prone to stress and toppling. See Crotch Cut.

Crotch Cut The shape of a treetop—U—after Duke Energy's periodic chainsaw massacres. The power company trims trees to protect the transmission lines, but does it in such a way that vulnerable parts of the trees are no longer protected from temperature extremes. The trees may weaken and die. See Cantilever and Sun Scald.

Decay Column It is what it sounds like: A column of dead wood that weakens a tree. The column is often surrounded by healthy tissue. Someone should start a death-metal band with this name. "Ladies and gentlemen, on your feet or on your knees, please welcome Decay Column!"

Hypoxylon Canker A type of fungus that lives in a tree. Branches die and the tree sheds some of its outer bark, exposing masses of brown fungus spores. All trees carry the fungus but succumb to it when they are weakened by disease, injury or old age.

Monoculture Many people love the symmetry of a boulevard of flowering dogwoods. However, if a pest or disease should strike those dogwoods, all of the trees could become ill. Mixing tree species makes the area more resistant to widespread disease.

Sun Scald Damage caused by exposing tree bark to temperature extremes and excessive light. The bark will darken, sink into the trunk and die. A tree that has been sun scalded is more vulnerable to disease. See Crotch Cut.

Windstorms Before you prune your trees to their barest essentials, remember that branches play a key role in preventing them from falling. Scientists have placed motion sensors in tree branches to measure how energy is dispersed in the wind. As it turns out, a healthy array of branches helps to scatter the energy. However, that energy is amplified on branchless trees or those with branches only on one side (see Cantilever), making them prone to toppling.

Zone 8 A Hardiness Zone is a geographic area that supports certain types of plants based on climate. Although Durham is currently in Zone 7B, City Urban Forester Alex Johnson is planting trees that thrive in Zone 8 because he anticipates climate will significantly change over the 30- to 70-year life of the trees.

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