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Have bagworms doomed blue spruce?

Q. My blue spruce had a type of bagworm on it about three years ago. I noticed the top turning brown along with some limbs on one side. I picked all the bags off that I could see and sprayed with an insecticide.

Last year it started having more brown spots and this year it looks terrible. I may cut it down. This tree was planted in 2003 or 2004 at a height of 6 feet. It’s about 15 feet now. What should I do with it?—William


A. Before removing your blue spruce (Picea pungens) you should have a certified arborist come out and take a look at your evergreen. Bagworms can be devastating if not controlled, and if allowed to survive and thrive during consecutive years they can lead to the demise of the host plant.

The only time to effectively spray with an insecticide labeled for bagworms is when they are not protected in their tightly woven bags. During the fall through mid-spring the only treatment is to hand pick the bags. Spraying is useful when the caterpillars hatch, emerge from their bags, find their way to the top of the tree, and are actively feeding.

Each female can lay 300-1,000 eggs; populations can increase drastically each year if not controlled. Hiring a certified arborist will ensure that you are getting reliable information and recommendations in terms of control or potential removal.

According to the International Society of Arboriculture (ISA), Big Beaver Tree Service in Nicholasville has a certified arborist on staff that serves your area. Call them at (859) 272-8548.

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