Mountain Pine Beetle Spraying FAQ

 

Frequently asked questions about the mountain pine beetle.

When does the mountain pine attack trees in Colorado?

Typically the mountain pine beetle is in flight from mid – July through August. However, startling new data suggests their season is rapidly expanding according to ecologists at CU- Boulder. Beetles were caught as early as May 22nd and as late as September 20th in their wide-ranging study.

 

There are mountain pine beetles in my tree. Can you stop it?

The short answer is no. Preventive tree spraying is the best known way to prevent beetles from infesting a tree. Other tactics such as pheromones which attract and trap beetles is at best uncertain in its effectiveness. Tree health care cultural practices such as fertilization and watering help a pine tree make more pitch, giving it more ability to push out MPB.  But that solution is far from being uniformly effective.

When should you spray for mountain pine beetle?

The only time to effectively prevent beetle infestation is to spray before they attack the pine tree. There are no remedial treatments once the pine beetle has colonized the tree. We time our pine beetle spray between April and June before the adult beetles emerge.

If the application is done in early spring, there must be some sort of sticking agent (known as a surfactant) in the mix so that the active chemical stays on the bark long enought o provide control.

Are the insecticides dangerous?

We primarily use permethrin based products that are only available to commercial grade applicators. We take great care with pets, especially with fish and cats, when conducting our operations.  The pesticides are toxic when wet so we always advise people to stay out of the way for about an hour or so, leaving more than enough time to dry in the Colorado climate. Also, following the label directions for personal protective equipment is required by law.

Some applications that contain carbaryl are available to the general public (and unlicensed tree sprayers). This is nasty stuff (that’s an arborist term:)) and we reiterate to follow label directions closely.

I thought mountain pine beetle wasn’t in the Denver area?

We have seen mountain pine beetle infestations from Boulder to Castle Rock.  Short of a chemical cure that kills off infestations, mountain pine beetle is a part of the Front Range arboriculture.