Baffle bark beetles by pruning pines in winter’s cold |

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Baffle bark beetles by pruning pines in winter’s cold

The winter months are not the usual time when we think about tree care – unless (knock on wood) Old Man Winter blows one over. But this is the best time to care for your conifers to help ensure strong, healthy trees year-round.

“All the pests that attack them are dormant during the wintertime and active during the summer,” explained Aero Acton, certified arborist and owner of Leaf It To Me, a Nevada City tree service. “We wait for freezing temperatures, which can be December through February or even March, depending on the season,” to prune trees.

The bark beetle’s job in nature is to thin the weak trees out of the forest. All these boring insects are attracted to weak and damaged trees by sense of smell, and they can detect them from as far away as 7 miles.

“A pruning cut is an injury,” said Acton.

This may not be as important to a logger out in the middle of the woods, but In the yard, you don’t want to increase your chances of attracting the beetles, he said.

It’s not to say that you would definitely attract them with spring or summer pruning, but you certainly increase your chances, Acton said.

That’s especially true in the spring – the worst time of the year to prune, because after a certain period of warm days, the beetles come out again. Their first of three or four hatch-outs is in the spring and the first is the largest, Acton said.

The way to avoid having a beetle problem is to avoid having a weak tree.

A tree “can be weak for many reasons, such as drought, over-crowding, root damage from construction impacts or pruning,” Acton said.

If you remove a pine tree in the spring or summer, have it hauled away, chipped, de-barked or tightly covered with plastic and buried into the ground.

If you just cut it down, leave it and come back, there will be beetles all over it, he said. The beetles will come to that neighborhood and look for other weak trees to attack.

Typically, a healthy tree makes compounds that beetles don’t like, and will have so much sap flow that beetles get pushed back out.


To contact Features Editor Carol Guild, e-mail or call 477-4219.

Types of pruning

• Crown cleaning: The selective removal of dead, dying, damaged and diseased branches (think of house-cleaning).

• Crown raising: Removal of lower branches to provide clearance, such as for a roof, drive-way or patio.

• A tree is only a hazard if there is a target and if some part of the tree poses significant threat of failing.

– Source: Aero Acton, Leaf It To Me