August 9, 2011 – Centennial, Colo.
The IPS beetle should really talk to the mountain pine beetle’s agent. Because they get a lot more press then the spruce killer IPS.
Our plant healthcare consultant Jeff Disler took photos of these spruce trees, the latest home for an IPS beetle colony, in Centennial.
“The spruce were in various stages of decline. It’s too bad. Instead of doing ongoing prevention now they’re looking at $3,000 in removal costs and no trees,” Disler said.
The IPS beetle attack depicted likely started in early 2010 when one of the four spruce in question started to decline rapidly. Unfortunately the homeowner neglected to call right away so it spread to three other mature spruce.
In doing a plan healthcare evaluation we look at neighborhood trees to get a sense of the overall condition of the arboriculture. In this case, we saw no other signs of IPS activity.
“I observed about 1000 beetles chewing away in these spruce. They hadn’t done their main flight yet but they gotta go somewhere. Basically the whole neighborhood is going to have to spray if they don’t want to lose their spruce trees,” Disler said.
The story is the same in other parts of Colorado. One IPS infestation begets another and pretty soon the whole community’s spruce trees are in rapid decline
IPS is a common group of bark beetles that infests pine and spruce trees, according to Colorado State University’s article about IPS.
IPS beetles are rarely successful in attacking healthy trees. Most problems occur to newly transplanted pines or when plants are under stress. However, the bad news is that most urban spruce trees are degraded in some way.
Good cultural practices such as deep root fertilization and winter watering maintain a healthy spruce tree. It can usually fight off an IPS beetle attack.
However if you’re spruce trees are less-than-perfect, then application of a preventive insecticide is the only way to be fully sure that the tree will not be attacked.
Spruce trees in Denver are still recovering from the drought that occurred last decade. So we recommend spraying all mature spruce and pine, even healthy ones. It’s really a lesson from increased bark beetle activity of all kinds in the continental US.
For a variety of reasons such as global warming, soil compaction in urban areas and drought, bark beetles are:
- more aggressive
- invading geographic areas that are not supposedly vulnerable
- targeting trees that are supposedly not the target size or species
To paraphrase CSU beetle expert, Dr. David Leatherman, bark beetles are not behaving how they are supposed to behave. They aren’t reading the books that say they’re supposed to behave in a certain way.
Hopefully we can make the IPS beetle famous as a case of successful control, not the killer of Denver’s spruce stands.