Here are some details of the biology of the Pouch fungus, from Martin MacKenzie, Forest Pathologist, at the South Sierra Service Area of the Stanislaus National Forest, located in Sonora California.
“The fungus is Cryptoporus volvatus; the pouch fungus. It immediately tells you the beetles have flown. This fungus has a special adaptation that allows it to shed its spores in the heat of summer at the same time as the first wave (sometimes the only wave) of beetles are leaving the tree they have just killed. After the beetles (and blue stains) have killed the tree the Pouch fungus comes along and decays the sapwood of the now dead tree. The fungus has a special covering (volva) over its pore layer, this layer prevents the spores from desiccating in the heat of summer. The spores would not escape if there was not a pore at the back and on the underside of the conk. The sun heats up the air in the pouch the air currents carry the spores out of the pore and they blow in the wind until they encounter a fresh beetle exit hole. The spores germinate and grow down the exit hole, through the bark and begin to decay the sapwood.
As an experiment in scaling I scaled up the size of the microscopic fungus spore until it was as large as a 3 inch ball, then I scaled up a bark beetle exit hole by the same factor and found that it would be as large as a 50 foot culvert. Just as easily as I can throw a tennis ball into a 50 foot culvert, the fungus spore can fall into the hole left by an escaping bark beetle.
The 3rd slide in the attached PowerPoint might interest you. It’s of a Ponderosa killed by the western pine beetle and the areas of flecked off bark is where the woodpeckers were once going after the late larvae and pupae of the Western Pine beetle. That beetle moves into the outer bark before it finally escapes, to seek a new host. The woodpeckers pounce on the tree at this stage and do their bit to reduce the beetle population. But alas they do not take them all, they just make a living off them.
In this past couple of years I have seen what appears to be the pouch fungus fruiting just a few months after I realized that the tree was dead. The truth is there were a lot of trees out there, that were dead, they just did not know they were dead.”
The first photos (taken by Paul Cooper) are of dead, standing ponderosa pines, with the fungus fruiting bodies growing out of the tree. Lower photos are of a single mushroom, showing more detail.
Click on an image to enlarge it.
Many homeowners associations and businesses are recommending the use of SPLAT Verb to protect ponderosa pine trees from being attacked by pine bark beetles. For example, this local article states “Verbenone is naturally produced by MPB and by several other species of bark beetle towards the end of a mass attack.” This text exactly matches the text at the isatech.com website, so it appears not much work was put into researching this.
What the article, or any other local sources, bother to state, and probably do not know, is that SPLAT Verb, alone, is not effective against western pine beetles. The local promoters of the use of SPLAT Verb are confused, and are giving misleading information to the public.
The active ingredient, verbenone, is an anti-aggregation pheromone that works against the MOUNTAIN Pine Beetle (Dendroctonus ponderosae), not the WESTERN Pine Beetle (Dendroctonus brevicomis). These are different species, with different habits and ranges.
The pine bark beetle that is killing our Tuolumne and Calaveras County ponderosa pines is the western pine beetle, D. brevicomis.
The mountain pine beetle prefers sugar pine, lodgepole, knobcone, and smaller diameter ponderosa pines. Mountain pine beetles are rarely found in ponderosa pines that are greater than 6 inches in diameter. In California, western pine beetles are by far the most important beetle attacking ponderosa pines, of all sizes, and are the cause of most ponderosa pine mortality.
Verbenone is a naturally occurring substance, and is created by the oxidation of alpha-pinene, a component of pine resin. Mountain pine beetles and Southern Pine Beetles use verbenone as a pheromone, and react to it.
The work goes back to the early least the 1970s. Field Response of the Southern Pine Beetle to Behavioral Chemicals. And even this work showed that verbenone alone was questionable, stating: “Traps with a 1:4 mixture of Endo-brevicomin and verbenone plus an attractant caught significantly fewer beetles than traps with the attractant plus either one of the inhibitors.”
This 1980 paper states “Attempts to use verbenone to protect living trees from D. brevicomis attack were inconclusive.” Effects of verbenone and trans-verbenol on the response of Dendroctonus brevicomis to natural and synthetic attractant in the field
This 2006 article also says that verbenone is not effective, as a stand-alone agent, against western pine beetles: Efficacy of Verbenone for Protecting Ponderosa Pine Stands From Western Pine Beetle (Coleoptera: Curculionidae: Scolytinae) Attack in California. It states: “No significant differences in levels of D. brevicomis-caused tree mortality or the percentage of unsuccessfully attacked trees were found between verbenone-treated and untreated plots during each year or cumulatively over the 3-yr period.” That means that trees treated with verbenone did no better than untreated trees.
There is also concern within the USDA Forest Service about the use of verbenone. Ken Gibson, of the USDA Forest Service, states, in a position paper on the use of verbenone, that results are inconsistent. There is even concern that low levels of verbenone will attract mountain pine beetles. See Using Verbenone to Protect Host Trees from Mountain Pine Beetle Attack. To quote from the paper: ” This lack of consistency in some verbenone trials has been a source of great frustration to the bark beetle research community.” He goes on to say “if someone were to ask any of us if verbenone protects host trees from MPB (mountain pine beetle) attack, we would have to honestly reply, “Sometimes!” A “silver bullet” verbenone is not!”
The conclusion is this: Verbenone is not effective as a stand-alone treatment against the Western Pine Beetle. It has been shown to be ineffective against this species of beetle, over a three year period, and its effectiveness against even the mountain pine beetle is inconsistent.
Verbenone, in combination blends, shows some promise, for the Western Pine Beetle, but this research is ongoing, and no product is yet available. And yet again, inconsistent results are reported. Some samples of the papers are:
1. Efficacy of “Verbenone Plus” for Protecting Ponderosa Pine Trees and Stands From Dendroctonus brevicomis (Coleoptera: Curculionidae) Attack in British Columbia and California. 2012. The paper states that verbenone alone had no effect on the density or success of attacks against the pines. But the researchers created a blend of four semiochemicals (natural chemicals released by an organism that affect the behaviors of other individuals): acetophenone, (E)-2-hexen-1-ol + (Z)-2-hexen-1-ol, and (–)-verbenone. They termed this blend “Verbenone Plus”, and it showed potential. The paper states “Verbenone Plus significantly reduced the percentage of trees mass attacked by D. brevicomis in one study, but in a second study no significant treatment effect was observed.”
We have an FAQ page giving some details about other control options.
The California Manroot, Marah fabaceus, is a fascinating plant we find here in the Sierra foothills. A native vine, it produces a distinctive seed pod, covered in spines. Below are photos of the fruit, showing the seeds it produces. It appears to me that the fruit bursts open due to gas pressure inside. I failed to witness the actual opening, but shortly afterwards, I heard the seed pod release gas. This pod produced 17 seeds.
Click on an image to enlarge it.
“It’s not a shame to have them; it’s a shame to keep them” is what a nice, older lady told me, probably in the late 1970s, when she called me out for a bed bug job.
I thought this was a striking piece of wisdom, and it is something I have not heard anyone else say, before or since. the phrase says a lot, and I placed it here to share her words. It is a good concept to know.
This article appeard in the 24 March 2016 issue of The Union Democrat, in the “Good Old Days” section by Bob Holton.
It reads: “March 16, 1867. A Sonora Apothecary delivery boy was lately sent to leave at one house a box of pills, and at another half a dozen leeches. Getting confused on the way, he left the pills where the leeches should have gone, and the leeches at the pill place. The folks who received the “bloody suckers” were astonished on reading the accompanying directions: “Swallow one every two hours.”
article from Union Democrat, 24 March 2016, in section “Good Old Days” by Bob Holton.