Brown spots on Blue Spruce

I just read your answer pertaining to a Blue Spruce dropping needles. I have a spruce that had a type of bag worm on it about three years ago. The first thing I notice was the top turning brown along with some limbs on one side. I pick all the bags off that I could see and sprayed with an insecticide I bought at a farm store. The next year it look better.

Last year it started having more brown spots and this year it looks terrible. I’m thinking about cutting it down. This tree was planted in 03 or 04 at a height of 6 foot. Its about 15 foot now. What do you think I should do with it.

Hi, William: 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. Understanding their life cycle is important in terms of when to take action.

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 between 300-1000 eggs; populations can increase drastically each year if not controlled. Early to mid June is the time in Kentucky to take action. 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 has a certified arborist on staff that services your area. The phone number is (859) 272-8548. For more detailed information, the following link is a publication on bagworms in Kentucky: https://entomology.ca.uky.edu/ef440. I hope this is helpful.