How does long-term drought and over-pruning affect our trees?

We get lots of rainfall here and there, but these days, the summers are much longer, hotter, and drier, and even sporadic rainfall, especially when showers are light, isn’t enough to sustain most plants. Trees may show no symptoms of ill health for years, then die, seemingly overnight.

But long-term drought takes its toll, silently leading to secondary, and often tertiary issues.   Borer infestation is one good example. These insects do not invade unless a tree is already unhealthy and declining. Valerie Luna recently got in touch about her tree which has borer damage.

But we also see other contributing factors, like the black, decaying bark at the tree’s base, which indicates that the tree was planted too deeply and is staying too wet on the trunk. It’s also likely not getting enough water out at the dripline, where it needs. These were the original issues, so you should always check with a certified arborist to be sure about the actual cause of decline, prior to acting on what you think it might be.

And what about over-pruned trees that don’t look great but sprout a lot of leaves that stay closely attached to larger branches, rather than expanding on newly formed side branches, as usual? Certified Arborist Vincent Debrock from Heritage Tree Care tells us this: over pruning reduces too much foliage, which in turn severely limits the tree’s capacity to produce energy through photosynthesis, which then forces the tree to draw from reserved carbohydrates and produce reactive growth, commonly known as suckering or water sprouts. If this growth is removed repeatedly for aesthetic reasons, it tends to weaken the tree even more, eventually causing dieback in the top of the tree, and exposing younger bark tissue to sunscald.