Pine Wilt Nematode and Mountain Pine Beetle Along the Front Range: Is There a Connection?

We've received several samples in the Diagnostic Clinic this month of Scots pine that have been hit with Mountain Pine Beetle (MPB) from areas along the front range and one of those samples also had Pine Wilt Nematode (PWN) (Bursaphelenchus spp.). So we are asking ourselves, which came first, MPB or PWN? And, is one exacerbating the other? To see if we can answer this question, we are collecting samples of MPB hit Scots pine that are being cut down in counties along the Front Range to process for PWN to see if there is any correlation. The specific counties we would like samples from are Larimer, Weld, Boulder, Adams, Jefferson, Denver, Arapahoe and Douglas. The samples should be from trees no higher than 6000 ft elevation. The samples should be collected from branch areas closest to the trunk and should be no more than 3 inches in diameter and about 6-8 inches in length. Samples will be processed at no charge to the submitter. Samples should also be sent within 1-2 days of the tree being cut down. Samples can be sent to the Plant Diagnostic Clinic, E215 Plant Sciences Bldg, Colorado State University, Fort Collins, CO 80523-1177. If you have any questions, feel free to call us at 970-491-6950.

Answering Questions About Spraying for MPB and Other Bark Beetles

I've fielded several phone calls this week regarding Mountain Pine Beetle/Ips Beetle and whether homeowner trees in the urban areas should be sprayed for prevention of MPB/Ips attacks. I asked Fort Collins Assistant City Forester Ralph Zentz, and his reply is as follows:

"In the Front Range urban areas, the main host is still Scotch/Scots Pine (about 80% or more). Austrian pines are rarely hit and I have not seen or heard of any othe them being killed by MPB in any of the communities. Ponderosa is the second most hit species of pine in our cities, but lodgepole, pinyon, bristlecone, eastern white pine and others have been hit as well. Mortality in scotch pine runs about 10% when they are hit; the same is true for Ponderosa.

In the foothills and mountains of the Front Range, the MPB population is building in the native Ponderosa according to Dave Leatherman, Entomologist, formerly with CSFS.

Spraying should occur prior to May, however there may be a few earlier flights, but (in my opinion) not enough to warrant earlier spraying. It is critical that people realize that just because a tree is hit, it does not mean it will be killed from the pest. 10% or less mortality is reported from all the communities from Colorado Springs north to Fort Collins."

In a previous blog posting, there is a link to 'Mountain Pine Beetle Information' from October 30, 2009 that provides the most recent information compiled by the Colorado State Forest Service and Colorado State Extension. Scroll down to the date and the link is at the end of the posting.

The links to fact sheets from CSU Extension on MPB and Ips/Engraver Beetles are posted here. These sheet should also provide information for concerned homeowners.
http://www.ext.colostate.edu/pubs/insect/05558.html
http://www.ext.colostate.edu/pubs/insect/05528.html

As always you can call the Plant Diagnostic Clinic with your questions, or contact your local County Extension office for the latest information.