Jon Shattuck, one of our service technicians, showed me some photographs he took that day (2 October 2018) of what he suspected of being foamy bark canker. He’d serviced a home in the Monte Grande area, and the homeowner showed him some oak trees, bleeding a foamy sap. I went up and looked. Indeed, this was foamy bark canker, the first case I am aware of in Tuolumne County.

The infected trees were interior live oak, Quercus wislizeni, and the area of attack appeared limited to this one clump of trees. The property owner, Kevin Penfold, said he’d first seen the foamy bleeds about five weeks ago, and they were much worse then.

I searched nearby trees for signs of foamy bark canker, and found nothing. Mr. Penfold uses firewood, but mostly from his own pruning. There is no indication that the beetles and their fungus were transported here. The simplest conclusion is that the oak bark beetles have carried the foamy bark canker fungus with them, via their own dispersal.

Scott Oneto, Farm Advisor for our area, says he saw foamy bark canker in Tuolumne County in 2016, at about the time we had the Angels Oak infestations.  But he, like us, had not seen it in 2017 or 2018, until this case. emerged. We must assume that the disease is widespread in our part of the Sierra Nevadas.

 

 

 

Here is a followup on Cooper1 and Cooper2 trees in Greenhorn Creek. We see some interesting changes. The Cooper1 tree, despite its decline is showing regrowth from the base. The third picture shows Cooper2, at the location of the branch with foamy bark canker, and it is showing good growth. Cooper2, in general, continues to decline, as does the adjacent oak, which we have not yet investigated.

See this for photo comparisons.

Photos by Paul Cooper, 31 May 2107.

 

 

 

29 October 2016

After taking video of the foam coming from a beetle entry hole, the next step was to open it up and see what was producing the foam. Below are photos and a video.  The video takes us from the surface to the beetle gallery. Note the white gel-like substance. That is probably the source of the gas in the bubbles. No beetle was found, but we may have touched a beetle elytra.

Please share your ideas on this.

 

 

 

29 October 2016.

We found a western oak bark beetle, Pseudopityophthorus pubipennis, in one of the cankers of the Cooper2 live oak branch. Cooper2 is an interior live oak infested with foamy bark canker. The beetle was small, about one and a half millimeters long. Sample collected 29 October 2016, by Paul Cooper.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

29 October 2016.

Paul Cooper collected the branch on Cooper2, as seen at this page. The image of the branch is below, and the red circle indicates the area that the following video and photos were taken from. We were able to video, and photograph, the holes emitting foam.

The diameters of the holes are about 0.25-.33 millimeters. Each foamy spot is associated with one of these tiny beetle entry holes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

25 October 2016.  Paul Cooper reports that he found another foamy bark canker infested live oak, in Greenhorn Creek, across the street from the Cooper1/golf course tree. This interior live oak tree does not appear to have cankers down at the base, but shows foamy attacks higher up, in the newer, and thinner, bark.

The tree is declining rapidly. This is more striking, being that Scott Oneto, Paul Cooper, Allan Ramorini and two of his lead men, and I, were at the “Cooper1 tree” about a  month ago, and none of us noticed any decline in this second tree, that is just across the street. The fading of Cooper1 was obvious, but none of saw it. Now, it is readily apparent that this tree is fading fast, and that this fading took only about one month.

To support this claim, we again took the July 2012 Google Street View image, and the 2 April 2015 Bing Street View image, and placed them here to compare the tree over time. Again, the tree shows no decline in the previous years. To see this tree, as well as Cooper1 (across the street), use this link.

 

 

 

Lab analysis has confirmed that the live oak near the golf course is a victim of foamy bark canker. I found some older images of this same tree using Google and Bing Street Views. The Bing photo is the most recent, dating from 2 April 2015, and was taken when the sun was behind the tree, putting the bole in shade, making resolution difficult. But the tree is clearly in excellent shape. It appears to have grown well since the 2012 Google image was taken.

In September 2016, the oak was half dead. That means that in less than 18 months, the tree went from healthy and vigorous, to severely infected and dying.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

18 October 2016:  The identification of Foamy Bark Canker is confirmed. Scott Oneto told us that the Escalen Lab reports that both samples he took at the Greenhorn Creek site were foamy bark canker.

 

Table of Contents

Initial report 9/22/16. Customer in Greenhorn Creek shows Paul Cooper the trees. Paul, having 15 years of experience in landscaping and another 14 in pest control, knew this was special, and took photos.

Basic biology A look at foamy bark canker, a new oak disease in our area of the Sierra Nevadas.

First photos   9/22/16 by Paul Cooper.

Scott Oneto’s sampling visit 9/28/16. More trees found. More holes in the first trees. Scott Oneto takes samples.

A live oak near the Greenhorn Creek gold course that is nearly dead due to an infection from foamy bark canker.

A video of the infestation, taken 28 September 2016 at Greenhorn Creek

Treatment of Foamy Bark Canker,  7 October 2016

Photos showing the changing look of the foam, 7 October 2016.

Video showing the changing look of the foam, 7 October 2016.

How fast did the golf course tree fade?

Paul Cooper finds another infected live oak. 25 October 2016.

Video of the foam being emitted from beetle entry holes 29 October 2016.

Looking inside a foaming bark beetle hole. 29 October 2016.

Retrieval of a western bark beetle from a canker 29 October 2016.

 

 

 

Initial Report

On 22 September 2016, our technician, Paul Cooper, was asked by a customer about some peculiar looking interior live oak trees on her property in the  area of Greenhorn Creek, Angels Camp. Paul took photos, pasted below. The owner of the property tells us that 4 trees are infected, and that she only noticed the problem in the last few days. Paul Cooper then returned and looked more, and spotted a dead live oak down the street from the first reported infected trees, that still showed signs of attack from foamy bark canker.

I sent the original set of images to Greta Shutler of the Tuolumne County Agricultural Department, who identified the ailment as possible Foamy Bark Canker. And it sure looks like it. See also: Pest Alert

Foamy Bark Canker Disease

This appears to be a range extension of the disease, as it has not yet been recorded in our area. Greta says foamy bark canker was discovered in El Dorado County, but this finding is new to Calaveras County. This disease was first reported in 2012, and published in September 2014, in a paper titled: “First Report of Geosmithia pallida Causing Foamy Bark Canker, a New Disease on Coast Live Oak (Quercus agrifolia), in Association with Pseudopityophthorus pubipennis in California“. Now it is in our area of the Sierras, and infecting interior live oaks, the same type of oak that that it is infecting in El Dorado county. In the following image, I added the new find to the distribution map from “Foamy Bark Canker A New Insect-Disease Complex on Coast Live Oak in California Caused by Western Oak Bark Beetle and Geosmithia sp.” This paper is an excellent resource and has many helpful photographs.

The disease is vectored by the western oak bark beetle, Pseudopityophthorus pubipennis. This distribution map is from A Field Guide to Insects and Diseases of California Oaks by Tedmund J. Swiecki and Elizabeth A. Bernhardt.

This is a description of the biology of pseudopityophthorus pubipennis from Swiecki and Bernhardt’s Field Guide to Insects and Diseases of California Oaks: “Adults bore through the bark to the interface with the sapwood. From the entrance hole, two tunnels, about 5 cm long combined, are excavated in the inner bark perpendicular to the wood grain. Eggs are laid in niches along these tunnels. As larvae hatch they begin tunneling in the inner bark (phloem) at right angles to the adult gallery, i.e., with the wood grain. Larval tunnels are up to 2.5 cm long for P. pubipennis and 1–2 cm long for P. agrifoliae. At maturity, the larvae tunnel to just below the bark surface and pupate at the end of the tunnel. Adults emerge and chew through the bark, leaving behind small exit holes (“shotholes”). Depending on the location, there may be two or more generations per year. Generations overlap, so adult beetles are always present during the growing season. Larvae and adults overwinter under bark.”

The beetles are said to attack weakened, dying and dead trees, as well as freshly cut oak firewood. Healthy oaks are not usually harmed by oak bark beetle attack. But there is a BIG CATCH here: the beetle carries a fungus with it. The western oak bark beetle is also the beetle commonly associated with  the sudden oak death pathogen, Phytophthora ramorum.

The fungus that the western oak bark beetle is said to carry, and cause foamy bark canker, is a type of Geosmithia, a group closely related to Penicillium. Geosmithia are known to be associated with bark beetles (source).

Initially the causative fungus was identified as Geosmithia pallida. See “First Report First Report of Geosmithia pallida Causing Foamy Bark Canker, a New Disease on Coast Live Oak (Quercus agrifolia), in Association with Pseudopityophthorus pubipennis in California.”

Extensive surveys and laboratory research has since revealed more than a dozen new species of Geosmithia in the western United States. The species causing foamy bark canker is now identified as one of these new species, tentatively called “Geosmithia species 41”.  This identification was done by Dr. Miroslav Kolařík, of the Academy of Sciences of the Czech Republic.

The fungal growth appears to girdle the plant, causing branch dieback and tree death (source). Additionally, it appears the beetle is necessary for the transmission of the fungus.

Since the beetles prefer weakened and drought-stressed trees, your best defense is probably keeping your live oaks healthy.

Watering oaks is the reasonable solution, but you must be careful to not over-water.  This is excerpted from Bill Tietje‘s article,  Native oaks stressed by drought may recover. “A deep watering followed by soil drying for a month or two should not harm the tree. In fact, a deep watering may be the best recommendation for invigorating your thirsty oak tree, thus providing some insurance that the tree will survive this current drought.”   I encourage you to read the whole article; it is short and to the point.

UC Cooperative Extension Farm Advisor Scott Oneto is now preparing to research and confirm the infestation.

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FIRST SET OF IMAGES of the foamy bark canker infected trees, in the Greenhorn Creek area:

Live oaks with foamy bark canker. Photo by Paul Cooper, Angels Camp Ca. 22 September 2016.

Live oaks with foamy bark canker. Photo by Paul Cooper, Angels Camp Ca. 22 September 2016.

Live oaks with foamy bark canker. Photo by Paul Cooper, Angels Camp Ca. 22 September 2016.

Live oaks with foamy bark canker. Photo by Paul Cooper, Angels Camp Ca. 22 September 2016.

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Scott Oneto’s Sampling Visit

On 28 September 2016, Paul Cooper and I met with Scott Oneto of UC Cooperative Extension, along with Allan Ramorini, Assistant General Manager of Greenhorn Creek. Scott Oneto has been working on the El Dorado County outbreak of foamy bark canker, and wanted to examine this possible find. Scott took samples for laboratory analysis, including Akif Eskalen’s lab at UC Riverside. Scott estimates results should be back within two weeks. His impression is that this might well be foamy bark canker, but the lab results will confirm this or not.

It was clear to Paul and the homeowner that the infestation has gotten much worse in the last few days, the number of foamy holes having increased greatly. We also found two more trees, about 75 feet from the initial cluster of trees, along the edge of the Greenhorn Creek Nature Easement Area.

Scott was having trouble finding holes that showed the characteristic horizontal tunnels made by western oak bark borers. He finally found a good sample, leading him to believe that the infestation on these trees is very new; that is, the beetles have just recently attacked. And that fits with the observations of the homeowner, and the rapid increase in the number of foamy holes on the initial trees.

Note: On 18 October 2016, Scott Oneto told us that the Escalen Lab results were back and that the disease was indeed foamy bark canker.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 A Second Location within Greenhorn Creek: A Large Dying Live Oak Infested Prior to the Original Report

These photos show a large, dying live oak, down the street from the originally reported trees. Paul Cooper spotted this dying live oak tree, and returned on Sunday, 24 September 2016, to investigate it further. He found that this tree also showed signs of foamy bark canker. This nearly dead interior live oak is fully Paul Cooper’s discovery, and he did this investigation on his own time. Kudos to Paul for finding it!!

Scott Oneto sampled this tree as well, on his visit on 28 September 2016. Lab results, from the UC pathologist’s lab in Riverside, confirmed this tree also has foamy bark canker.

What this tells us is that the beetle infestation that Paul originally reported was not the initial spot. This tree was infested prior.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Inside the dying live oak.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Video of the Infestation from 28 September 2016

 

 

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7 October 2016:  We start the treatment for Foamy Bark Canker

With the approval of the property owner and Greenhorn Creek, using the Arborjet system, we injected the infected interior live oaks with the insecticide emamectin benzoate, and the fungicide Propizol (propiconazole). We’d consulted with Dawn Fluharty, Arborjet’s Regional Technical Director for our area, who told us that Emamectin and Propizol were used in a coastal area, with excellent results. The idea is that the emamectin would kill the beetle, which vectors the disease, and the fungicide would kill the fungus within the oaks, and stop it from killing the tree.

A search of Google Scholar comes up with no published research on the treatment of foamy bark canker, so this report of our injections may be valuable to others. Leaving untreated, control trees, is a standard experimental procedure, but our objective is to completely stop the spread of the foamy bark canker disease in the Greenhorn Creek area, at least for the now, and we do not want to leave any trees infested, as the disease will likely spread rapidly throughout the area. We still do not know where this infestation came from, or whether it is more widespread.

Ryder Richards, our primary tree injector, did the injections. We used maximum label rates for each material. Ryder injected about every five inches of truck circumference, and used the maximum dilution rates. We will be watching to see how the disease progresses.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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 The changing look of the foam. 

We noticed that the foam around the beetle holes was not as foamy as on 22 September 2016. These photos, taken 15 days later, on 7 October 2016, are noticeably less foamy. In many cases the foam has converted to a thick, not foamy resin, or has glazed over and shrunk some.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Video of the Infestation 7 October 2016, showing changes in appearance of the foam.