How bad is the pine bark beetle problem this year?

Well, I haven't seen any Dendroctonus at all this year. Last week I was digging an Ips calligraphis out of a pine tree, and for a moment I thought I saw the tail end of a black turpentine beetle (they're relatively large). Well, it hid from me--they always do--and I wasn't able to get the specimen in a bottle. For the record, it's not at all uncommon to see more than one species of pine bark beetle at the same time.

Contrary to popular belief, Ips and sawyers can be found--active--on the same tree at the same time.

Anyway, they're bad this year. Not as bad as 2009, but compared to 2008, when they were hardly an issue, they're killing pines all over town. I found half a dozen infested/dead pines near Memorial and San Felipe, one near Memorial and Wilcrest, dozens out near Fry and Clay in Katy, some up at Champion Forest and Cypresswood. Let's see, Voss and Katy Freeway, Kluge and Huffmeister in Cypress...

One important point: don't let anyone tell you that your tree can be saved once the pitch tubes appear. There are also football-shaped marks on the bark; these are also indications that it's too late. Have the tree removed. Preventive bark treatments with befenthrin are very effective, especially if properly and religiously applied at 4 month intervals. The Texas Forest Service and some other researchers are working on systemic treatment with emamectin benzoate, which promises to provide 2 years of protection. This would be great--if you could get people to pay for it. Of course, the Bartlett lab, headed up by Dr. Don Booth, will have to do their own battery of tests.

I have seen trees that appear perfectly healthy succumb to pine bark beetle attack, but there is always more than meets the eye. All a tree really needs is a loss of turgor pressure at the right time for the attack to be successful. Most pines in the suburban setting are growing in junky soil. In most situations the turf grass has sapped the soil of all nutrients, foot traffic and pavement have compacted the soil, rendering it anaerobic, irrigation systems have caused moisture stress, and as a result the soil is largely devoid of organic matter and beneficial soil biology.

What I'm saying is the apparently perfectly healthy pine tree that succumbs to pine bark beetles usually ain't as healthy as it may look. I've never seen an infested pine, where I couldn't point to some factor or other that could have contributed to momentary loss of turgor pressure.

So, fertilizing is still the best way to reduce susceptibility. Generally speaking, trees whose nutrient needs are being met--running on all eight cylinders, so to speak--are much less susceptible to drought, over-irrigation, turf-grass competition, foot traffic, pavement, construction damage, and (dare I say it?) lightning (more on this here).

Of course (and I'm still speaking in general terms, here, not just about pines), fertilizing is inferior to promoting healthy soil. This means aerating, incorporating organic mattter and encouraging a healthy soil biology (If you build it, they will come).

Now, we haven't really done extensive testing on preventing pine bark beetle attack using root invigoration, the procedure that does exactly that (aerate and incorporate organic matter into the soil, usually to a depth of 7-9 inches, and to a radius of at least 8 feet for a mature pine), but the principle applies.

So, in summary, pines can be protected from attack by a combination of soil nutrition and preventive bark treatments, and don't let anyone convince you that a pine can be treated once it's been attacked.

Please feel free to leave a comment or send an email. If you're looking for a TCIA Accredited Houston Tree Service or Certified Arborist, call the company I've worked for since 2002, Bartlett Tree Experts, at 713-692-6371. This is my personal blog--it is not affiliated with Bartlett Tree Experts.