NEW OAK THREATS WORKSHOP

I helped out at the “New Oak Threats Workshop” today at the Huntington. This was an outreach program for tree professionals and the general public to alert them to the spread of the Polyphagous Shot Hole Borer and what steps they can take to help stop or slow down the spread of this potentially massive threat to both native and ornamental trees here. Much of the information about this pest can be found here on Dr. Akif Eskalan’s lab page, but some important new information was revealed at this seminar. Here’s my summary of what that is:

-Chipping infested wood, solarizing it and leaving it on site under a sealed tarp or composting the chips is the best way to prevent the beetle from re-emerging from cut wood and infesting new trees or re-infesting already infested trees and increasing the level of damage to the trees.

-Several insecticides have been tried on the chipped wood and two common ones have proven effective (at preventing beetles from emerging from the chipped wood; trials on trees are not finished).

-This infestation is so large and potentially devastating that Dr. Akif’s lab is reaching out to tree professionals, horticultural professionals, and governmental departments that deal with trees for help in identifying possible infestations.

-California State University San Bernardino is hosting a web application that can be opened up in your smartphone to report suspected shot hole borer or suspected gold spotted oak borer occurances. The app uses your phones gps to report on the location of the damage. If you want to be part of the team that can help deal with these threats to our oaks and other plants, both native or non-native, just cut and paste this link: (http://wrimedia.csusb.edu/oaktree/mobileapp/survey.php ) into an email to yourself and open it up in your smartphone.

-The number of tree species affected by the borer is growing; over 200 trees are known to be attacked by the borer, and the list of reproductive hosts, i.e. hosts that are not only attacked by the borer but help to spread the infestation, has grown. The reproductive host list now includes 22 species and will probably increase (California native plants are in red type): 

·           Box elder (Acer negundo)

·        Castor bean (Ricinus communis)

·        Avocado (Persea americana)

·        English oak (Quescus robur)

·        Coast live oak (Quercus agrifolia)

·        California Sycamore (Platanus racemosa)

·        Big leaf maple (Acer macrophyllum)

·        Mimosa (Albizia julibrissin)

·        American sweet gum  (Liquidambar styraciflua

·        Silk Tree (Albizia julibrissin)

·        Coral tree (Erythrina corallodendon

·        Titoki (Alectryon excelsus)

·        Blue palo verde (Parkinsonia florida)

·        Palo verde(Cercidium floridium)

·        Tortuosa (Salix matsudan)

·        Weeping willow (Salix babylonica)

·        Red Willow (Salix laevigata)

·        Trident maple (Acer buergerianum)

·        Japanese maple (Acer palmatum)

·        Evergreen Maple (Acer paxii)

·        Chinese holly (Ilex cornuta)

·        Brea (Cercidium sonorae)

·        Black bean (Castanospermum australe)

·        Camelia (Camelia semiserrata)

Here are some links to more information about the Polyphagous Shothole Borer:

CR Today: The shot hole borer

CISR: Tea Shot Hole Borer

Photos: Tea shot hole borer beetle found in La Habra Heights – - Whittier Daily News Media Center

RIVERSIDE: Avocado-killing pest identified at UCR | Breaking News | PE.com - Press-Enterprise

UCR scientist discovers cause of avocado-killing disease

Photo Gallery: Tea Shot Hole Borer gallery | Western Farm Press

Meet the beetle: Asian pest a threat to California's avocado crop - Los Angeles Times

CISR: The Center for Invasive Species Research

CISR: Invasive Beetle Species

Latest Greensheet Edition | California Avocado Commission

Euwallacea fornicatus - Tea Shot Hole Borer, in the Castor bean forest - YouTube

UC Cooperative Extension, Ventura County - Agriculture and Natural Resources Blogs

Beetle-fungus disease threatens crops and landscape trees in Southern California

Spread of fungus-farming beetles is bad news for trees

ceriverside.ucdavis.edu/files/141044.pdf

First Report of a Fusarium sp. and Its Vector Tea Shot Hole Borer (Euwallacea fornicatus) Causing Fusarium Dieback on Avocado in California

UCR scientist discovers cause of avocado-killing disease

Beetle, fungus cause concerns for California avocado growers - The Grower

ceriverside.ucdavis.edu/files/138734.pdf

New Oak Threats Workshop - Agriculture and Natural Resources - University of California

Join me, I'll be helping out here showing participants examples of Polyphagous Shothole Borer damage at the Huntington. I'm hoping that this forum may also provide some new insights on the control and management of this and the Gold Spotted Oak Borer. These two pests are currently considered a serious threat to oak woodlands.

New Oak Threats Workshop - Agriculture and Natural Resources - University of California:

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Video Blog for November 28th, 2012

*Update Possible Polyphagous Shot Hole Borer in the Wild on Coast Live Oaks

Just got back from a property located about 15 minutes northwest of here. The manager of the property found what looks like Polyphagous Shot Hole Borer on five Coast live oaks located in an historic stand in an unirrigated area. All five are dead or near dead, and the signs die back occurred within a months time. I am waiting on confirmation from Dr. Akif Eskelan and the folks at UCR, but it it isn't PSHB then its something that looks just like it. Below are images of the trees that were infested. If you see anything like this or what is described here, please contact me as soon as possible at 626 821-3236
Update: Akif Eskelan's lab has confirmed that this is NOT an infestation of PSHB (That's a relief). However it may be a previously unknown borer and fungus combination. 

-Frank McDonough, Botanical Information Consultant at the L.A. County Arboretum and Botanic Garden.

Possible Polyphagous Shot Hole Borer on Coast live oak (Quercus agrifolia)

Notice the dark, oozing stains that appear on the trunk. 

This almost dead Coast live oak has noticable soaking spots up and down its trunk. Most of these appear on the south side of the tree. 

Possible PSHB entry holes with oozing fluid. 

A Nuisance Bug that Doesn't Stink

A fellow employee here at the Arboretum brought this to me. It was massing outside of her house in large numbers. They seem to be making there way into her house and becoming a nuisence there.  It's about a 1/2 an inch long and has really nice red markings on its thorax and abdomen. Turns out this is the Red-shouldered bug . It's listed as feeding on the seeds of Koelrueteria trees so control consists of keeping the seeds raked up off of the ground. I asked my fellow employee if she had any Koelrueteria trees around and she said that, yes, she had three of them in the same area as where the bugs were a problem.

First Fall Colors

Another Possible Polyphagous Shothole Borer Infestation in Altadena

Visible ooze possibly from PSHB infestation.

I received an email from resident of Altadena who had just had a large oak transplanted this last November. The tree was not doing so well and he was wondering what was happening to the tree. Turns out the tree may be suffering from PSHB infestation. Pictures of the tree he sent me seem to show the typical 3-6 inch small oozing spots with sometimes discernable small white spots of sawdust surrounding small 1/8" holes in the bark. This is just a photo diagnosis so it is no way the final word on this tree. Although live oaks are known to be reproductive hosts for the PSHB, how destructive they might be to oaks in good health is still unknown.

3" by 2" ooze spot and entrance hole (midway on the left of the spot).

 

Oak trunk showing ooze spot.

 



Oak canopy showing thinning. How much of this thinning is due to PSHB is unknown; the tree was transplanted less than a year ago.

 

Elder Blues

I got a call about a sick 'Alder' tree that was just about dead, turns out the tree was a Box elder, a type of maple tree with compound leaves that don't look like a maple. This tree is very confusing. It's also the number one victim of the new Polyphagous Shot Hole Borer (PSHB).  This pest is just hideous and seems to be gaining new victims (known in plant pathology circles by the innocuous term 'hosts') every month.I asked the caller to send me pix of the tree by email and sure enough, it was infested with  PSHB.

Here are some of the pix he sent me:

The Box elder's confusing leaves. 

Notice the dark wet-looking patches with the mounds of sawdust in the middle of them. 

An even better look at the oozing and the sawdust spots. 

(Possible) Shot Hole Borer Blues

The Polyphagous shothole borer is starting to make the news, and rightly so. Just last week I found one of our Brazilian peppers possibly dead from the beetle/fungus combination. 

Brazilian pepper tree (Schinus terebinthifolius) that may have been killed by shot hole borer. 

Closeup of branch from possible shot hole borer infested Brazilian pepper tree. The dark stains may be from the Fusarium fungus that the beetle infects the tree with. 

This pest/fungus combination is starting to show up all over the place -it's quite an extensive infestation. Just before I started writing this post a gentleman called about his tree that was dying and emailed me some photos of it; it was a Box elder. Box elders have been the canary in the coal mine for this thing and his was located in Monrovia. I'll be writing more about it shortly, and I'm writing more extensive article about the infestation for the Arboretum website.

Pest and Disease Threats to Southern California Oaks: I'll Be Presenting At This Seminar

Welcome! - Pest and Disease Threats to Southern California Oaks:

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Plant Information Class Links

I'd like to thank everyone who attended yesterday's plant information class; we had a great turnout. Here are the links I promised you yesterday:

Chill and Fruit

DWN: Garden Compass: Chill Out!
Chilling accumulation: its importance and estimation
Chill Calculators - Fruit and Nut Research & Information Center
Chill Calculators - Fruit and Nut Research & Information Center
L.E. Cooke Company - What Are Chill Hours?
FRUIT CULTURAL DATA -- A
Fruit Facts
National Gardening Association

Winter Annuals

www.ces.ncsu.edu/depts/hort/floriculture/RR/pdf/winter/Winter_Annuals.pdf
www.uaf.edu/ces/districts/tanana/mg/manual/chapters/10-Annual-and-Perennial-Flowers.pdf
Annie's Annuals - Get Ready For Fall!
Search or Buy Plants and Flowers Online - Annie's Annuals & Perennials

Mount SAC Horticulture Department Tour

This months plant information class met at the Mount SAC horticulture department for a tour by production assistant Ruben Flores. Ruben showed us the new demonstration garden, the new turf demonstration garden and wiffle ball diamond, a production greenhouse devoted to Poinsettia production, and several interesting small garden areas that were chock full of lush plantings. 

The cactus and succulent demonstration garden; it was just planted the week before our tour. 

The new wiffle ball diamond; this was no easy project -the first batch of decomposed granite had to be replaced because it was contaminated with mud. 

We saw this pretty blue-flowered weed growing around the new ly constructed classrooms there. Solanum eleagnifolium is a member of the nightshade family that some consider a candidate as a water saving ornamental plant; problem is that it's also a weedy plant that is toxic to livestock. 

Our guide, Ruben Flores, started our tour in the houseplant greenhouse. 

A large production greenhouse devoted to growing Poinsettias. Their are bout 4800 of these growing in this greenhouse, if they were to sell these at retail for $10 a piece they would gross $48,000. 

Ruben shows us one of the hidden shade gardens. 

Hidden shade garden. 

The plants growing on the log in this greenhouse are orchids and ferns. 

Society garlic blooming in the hot summer sun. You can guess what this smelled like. 

A beautiful South African cycad. 

There was a large shade-cloth covered garden located in front of the horticulture department offices. Besides being a relaxing water feature the pond in the garden contained more than a few beautiful Koi.

Here's a diagram of the demonstration garden that's currently being installed at Mt. SAC. 

Grafting Tomato Plants

One of the big problems with growing heirloom tomatoes is their lack of resistance to root diseases and nematodes. Grafting an heirloom variety on to a vigorous disease-resistant root stock not only gives the plant resistance to these disease, it can also lead to earlier fruiting and larger fruit as well. You can buy grafted tomatoes out of state (although right now plugs of a tomato graft called 'Might-Mato" are being sold by a California plug grower and may start showing up at retail nurseries here soon) , or you can try your hand at grafting your own. Tomato grafting usually requires a greenhouse, but you might be able to get results in a plastic tented area under shade-cloth.  Here are some videos and links that will help you get started:

North Carolina State pamphlet on tomato grafting. 

University of Connecticut IPM tomato grafting webpage.

Betterheirlooms.com (sells tomato grafting kits)

Article on tomato grafting on "The Atlantic" magazine website. 

Where Can I See Examples of Mediterranean Gardening?

Q. I'm designing/planting out my back yard mediterranean style here in Santa Clarita. Can you tell me where I can go and see a nice example of this landscape style? Somewhere open to the public?
I'm having a blast learning all about this type of garden!

Thanks, Jenny

A. Hi Jenny,

We have good examples of Mediterranean gardening here at the Arboretum. Our entryway, South African section, South African aloe walk, Demonstration Garden, Canary Island Exhibit and our Water Conservation Garden are all good examples of plant selection that is appropriate to our Mediterranean climate here. Our sister garden in Torrance, the South Coast Botanic Garden , has a Mediterranean garden and there is a public community garden, the Arlington Garden, whose eclectic style consists mostly of Mediterranean garden elements. Below are some examples of Mediterranean climate appropriate gardening here:

The Undersea Garden's plants are perfect for Mediterranean climates like ours. 

South Africa receives most of its rain in the winter and then stays mostly dry for the rest of the year. This is a true Mediterranean climate so many of the plants that grow there are perfect for Mediterranean gardens. Pictures above is the aloe trail winding through the South African plant collection here. The exaggerated colors are the result of the setting sun.  

Our Demonstration Garden, located fairly close to the Arboretum's entrance, has several small sections devoted to Mediterranean and California native gardening. 

Selected Questions From the Last Two Weeks

Was given an Ice-cream bean tree (Inga edulis).  Wanted to know how to grow it here.  Has it for 3 years under a huge Ficus tree in a pot.	Advised that it might not survive our winter because it would freeze over at 27F. http://www.tradewindsfruit.com/ice_cream_bean.htm Also asked that if the tree successfully produces fruit to bring it over for ‘inspection’.
Her 40 years old cypress trees are dying.  She lives in Malibu.  She actually sent over some sample leaves to us by mail.	Told her the trees are dying from Cypress canker, a kind of fungi. Once your cypress get the fungus there is little you can do to prevent it from eventually killing the tree. Pruning can extend the life of the tree, but it is vitally important to disinfect your pruning equipment between each cut. One thing that really helps promote the fungus is the number of Italian cypress trees you have in your neighborhood and how close together your cypress trees are planted. Closely planted cypress spread the disease quite readily, and if your neighbors have lots of cypress planted nearby, they can serve as sources of infection for other Italian cypress in the neighborhood. Another reason you have the infection now and not 40 years ago (the fungus was first detected in the 1920’s) is that the range of this fungus has been slowly spreading over time Cypress canker links: Fungus from California suspected of killing cypress trees worldwide | Nature | The Earth Times Gene sleuths trace tree-killing pathogen back to California San Diego Master Gardeners - FAQ - Italian Cypress turn brown Italian Cypress Video – 5min.com CYPRESS CANKER: A Pandemic in Progress - Annual Review of Phytopathology, 36(1):91.
I work on the Master Gardner help line and have a question I do not know how to answer. I would appreciate any help you can give. " I have a Liquid Amber question for Santa Monica. When do the trees defoliate, and for how long? I'm trying to plant a winter vegetable garden and my hope is the sun would shine between the bare branches. In the summer the sun is directly overhead avoiding the tree. "	Hi Rose, Liquidambars here defoliate in late November early December or later (they’re seem to be the last to put on color as well) with re-foliation occurring around March through April. That could be different for Santa Monica because it is not as cold; they could re-foliate sooner.
Our 80-yr-old mission fig tree has splotchy yellow areas on its otherwise dark green leaves. The tree has lots of small green figs on now, but they seem a bit smaller, as do the leaves, from normal. I did some on-line research, and it could be fig leaf rust. How do we tell for sure? Could I send you a couple leaves to I.D.? What's the cure? We have a dog who eats figs - loves them - and will even chew on fallen leaves because they're so good! We don't want to use herbicides that will harm her or us or even the squirrels and other connoisseurs of these figs. Here's some photos of one leaf, front & back, and of others on the tree.  I hope you can tell something by these photos -- it's more obvious in person.   We live in 90064 - in the NW quadrant of the I-10 and 405, west end of Rancho Park Golf Course.	Hi Paula, Your fig looks like it has Fig Mosaic Virus. There is no cure; it’s best to get a resistant variety –Black Mission is the most susceptible to this virus which is transmitted by mites or by rootstock. Spraying may work for rust, but not for viruses. However you can prevent the spread of the virus to other Fig trees by spraying for mites on a regular basis. UC Davis page on Fig Mosaic Virus: http://www.ipm.ucdavis.edu/PMG/r261100611.html

Peach Tree is Dropping the Ball

Q. Can you help me resolve a problem that has developed with my two peach trees? They are now giving reasonably good quantity and good size fruit, but the problem that has developed is that the fruit drops before it is ripe. Is there anything that can be done to help the tree hold on to the fruit until maturity?

A. Peach trees regularly thin themselves out before ripening occurs; if this didn't happen the peach’s branches would break under the weight of the ripening fruit. In fact, when the peach starts to show signs of fruit dropping (it's starting to self thin) it isn't a bad idea to water the tree heavily and then, the next day, shake the main trunk gently but rapidly to thin out the juvenile peaches before they get too big and pose a risk of collapsing the branches that bear them.