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Nursery and Floriculture Alliance

From the UC Blogosphere...

Butterfly Ballet

A Western tiger swallowtail nectarine on a butterfly bush. (Photo by Kathy Keatley Garvey)

If you plant it, they will come. Western tiger swallowtails (Papilio rutulus) can't get enough of our butterfly bush. For the first time ever, we saw two of them and managed to get both in the same image. Courtship? Curiosity? Chance...

A Western tiger swallowtail nectarine on a butterfly bush. (Photo by Kathy Keatley Garvey)
A Western tiger swallowtail nectarine on a butterfly bush. (Photo by Kathy Keatley Garvey)

A Western tiger swallowtail nectarine on a butterfly bush. (Photo by Kathy Keatley Garvey)

Mirror image! A Western tiger swallowtail spots a member of its species. (Photo by Kathy Keatley Garvey)
Mirror image! A Western tiger swallowtail spots a member of its species. (Photo by Kathy Keatley Garvey)

Mirror image! A Western tiger swallowtail spots a member of its species. (Photo by Kathy Keatley Garvey)

Well, hello there! A Western tiger swallowtail checks out another one. (Photo by Kathy Keatley Garvey)
Well, hello there! A Western tiger swallowtail checks out another one. (Photo by Kathy Keatley Garvey)

Well, hello there! A Western tiger swallowtail checks out another one. (Photo by Kathy Keatley Garvey)

It's up, up and away. (Photo by Kathy Keatley Garvey)
It's up, up and away. (Photo by Kathy Keatley Garvey)

It's up, up and away. (Photo by Kathy Keatley Garvey)

Posted on Monday, August 3, 2015 at 8:34 PM

Firescaping can protect homes during wildfire season

The landscape adjacent to the house is non-combustible.
Landscape + fire-prone area x protect = firescaping. The newly coined word offers hope to people who love living in wildland areas but fear a wildfire could wipe out their homes and belongings, reported Suzanne Sproul in the Inland Valley Daily Bulletin. The article also appeared in the Long Beach Press Telegram, the Daily Breeze and the LA Daily News.

UC Agriculture and Natural Resources (UC ANR) experts says its impossible to eliminate the risk, but firescaping can lessen the danger.

"I know people want to avoid moonscapes in their yards, but there are plenty of choices out there," said UC ANR Cooperative Extension specialist Tom Scott.

The article suggests homeowners

  • Trim overgrown plants
  • Replace highly flammable plants and trees - such as eucalyptus and palms - with less flammable plants - such as ocotillo and Calla lilies
  • Use creative hardscapes, such as non-combustible fencing and inorganic mulches

The article included a link to UC ANR Cooperative Extension's information on fire safe landscaping.

Posted on Monday, August 3, 2015 at 1:54 PM

Blue Oak Going Pink?

Help for the Home Gardener from the
Help Desk of the Master Gardeners of Contra Costa County

Client's Question and Request:
  Hi, the pink fungus-like growth in the pictures below is spreading on my oak tree leaves. Can you advise?  I have seen a little bit of this in the past, but this year it's really spreading fast; if you look at my tree from further away it is starting to have a pink cast, so there's a lot of this stuff!  Thanks for any help you can give. 

OakLeaf Gall
Blue Oak Turing Pink?

MGCC's Help Desk Response and Advice: Thank you for sending us the photos of your oak tree. What you are seeing are galls which are distorted, sometimes colorful swellings in plant tissue for which there are many causes such as wasps and other insects, fungi, nematodes, parasitic plants, etc.

The gall in your photos is one is one of the more spectacular galls seen in our oak woodlands and was recently observed in Hidden Lakes Park in Martinez. It is caused by an insect called a gall wasp which is about the size of a fruit fly. The wasp lays its eggs in the leaf. The developing larvae provide substances to induce the tree to form galls which provide shelter and food for the larvae. There are over 100 species of wasps associated with California oaks, and a species such as the Valley Oak or Blue Oak can have many different wasps associated with it. Each of these gall wasp species lays its eggs not only on specific parts of a tree, but also on certain species of oaks. For example, gall wasps associated with blue and valley oaks do not occur on coast and interior live oaks.

From your photo, it appears that your tree may be a Blue Oak (Quercus douglasi), in which case the Crystalline Gall Wasp (Andricus crystallinus) may be causing the galls you are seeing. The Iowa State University Bug Guide has photos of various galls, including that of the Chrystalline Gall Wasp which might help to confirm what you are seeing

Your photo shows some galls which are fuzzy and some which are smooth. The UC publication "Oak Woodland Invertebrates" describes Chrystalline galls as pink to reddish, often densely covered with reddish or brownish hairs. And notes that if the larva of the gall fails to develop normally, possibly due to parasite attack, the fuzzy hairs are not produced and the galls remain bare. If you would like to bring a sample of your oak leaves with galls into our Help Desk office, we can look at them under the microscope and might be able to confirm which gall wasp species is on your tree.

While a few types of galls can cause limited leaf or twig die back by blocking the vascular tissue, most wasp galls cause little or no lasting damage to oaks. For more information on oaks and their insects and diseases, you might want to download a free pdf copy of the USDA publication titled "A Field Guide to Insects and Diseases of California Oaks"

It is hard to believe that such a tiny insect is able to create so many galls on one tree!  A recent issue of Bay Nature Magazine included an observation written by Ron Russo, retired Chief Naturalist for the East Bay Regional Park District, which highlights the magnitude and significance of such a tiny insect.

"On the east side of Briones Regional Park, in the late 1980s, I found a blue oak that stood about 30 feet high and looked quite healthy. But this tree supported a huge population of the cynipid wasp (Andricus kingi). Its red, cone-shaped galls covered every leaf that I could see–all the way up into the canopy, a dozen or more galls on each leaf. I calculated that a modest-size tree with 10,000 leaves could easily support 120,000 gall wasps of just this one species, excluding any other gall insects and their associates. Then by adding conservative ratios of gall parasites, hyperparasites (insects that attack parasites), and inquilines (insects that eat gall tissues, but will often kill any insects they confront inside the galls), I arrived at the astonishing number of just under 200,000 insects using one blue oak as a result of A. kingi galls and larvae. Even if these numbers are conservative and reached only during cycles when populations for a species are at their highest, perhaps once every five to 10 years, the ecological significance of a single blue oak–and blue oak woodlands–begins to come into focus."

You might want to monitor your oak tree and contact us again if you see significant twig die back. Otherwise, the galls are just part of nature.

Enjoy your tree.

Help Desk of the Master Gardeners of Contra Costa County

Note: The  Master Gardeners of Contra Costa's Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email:, or on the web at

Posted on Monday, August 3, 2015 at 12:17 AM

Asian Citrus Psyllid




By Leonard Cicerello  UCCE Master Gardener


Why do I have a yellow sticky card on my lemon tree?  Jack, Los Osos


Periodically, insects from other countries end up in California and can create serious problems for farmers and homeowners.  Since these insects are new to the area, they have no natural predators here. Therefore, it takes a lot of time and money to figure out how to control them or eradicate them, if necessary. New insects find their way to California more often that we might realize. The Center for Invasive Species at UC Riverside reports that an average of 6 new species becomes established in California every year resulting in an estimated $3 billion in economic losses.


The Asian citrus psyllid (ACP) was found in Southern California in 2008 and has since made its way up the coast and to the San Joaquin Valley. ACP is mottled brown in color and about the size of an aphid, approximately an eighth of an inch long. They feed on all varieties of citrus including some closely related ornamentals like mock orange and orange jasmine. It prefers new tender growth and injects a salivary toxin while feeding that causes the new leaf tips to twist or burn back.  The bacterium that it injects causes the disease Huanglongbing (HLB).  HLB causes shoots to yellow and results in asymmetrically shaped fruit.  The disease can kill a tree within 5 to 8 years and there is no known cure for the disease.

A biological control program began in 2012 with the release of a tiny wasp, Tamarixia radiata. This wasp parsitizes ACP and is completely harmless to pets and humans. Researchers continue to monitor and evaluate Tamarixia and its ability to manage ACP.


County agriculture officials are working closely with the California Department of Agriculture (CDFA) to monitor for ACP by placing yellow sticky cards in commercial orchards and residential trees.  The public can help stop the spread of ACP by not moving citrus plants between counties. If you have citrus in your yard, examine the new tender growth for any signs of the pest.  If you suspect ACP, contact the CDFA Exotic Pest Hotline at 1-800-491-1899.

For more information, download the free UC ANR publications on ACP and HLB. 




Posted on Sunday, August 2, 2015 at 1:35 PM
  • Author: Leonard Cicerello
  • Editor: Noni Todd

Daily Life For Master Gardeners

One Ugly Bug

By Andrea Peck


During one of the recent stormy nights, I encountered two interlopers creaking along my kitchen tile. The room was dim, barely lit by the patio light that held watch for flooding. A warm breeze swirled in as that lovely sound of rain pummeled the concrete. I saw them before they saw me: potato bugs. They must have come in to rescue themselves from the sodden soil.

Known as Jerusalem crickets, the potato bug is an unappetizing beast of an insect. They grow from 1-2 1/2 inches in size and are as ugly as I'll get out. Sheathed in a yellow-orange skin that is reminiscent of bile, their skull-like head houses long, thin antennae. Their legs are rubbery and bent up with attached digits that resemble an electrocuted broom. But, I think the epicenter of that queasy, shivery sensation resides in the oversized larva-like body.

How to get rid of them, while rain creates a slip-n-slide of the patio?

Years ago I met a potato bug in its natural environment: under a rock. The bug made me shriek to myself. I dropped the rock and took a breather. But the second meeting was much more earth shattering. It was at night. I walked along my dark hallway, into the kitchen and saw it there like the lump of creepiness that it is and thought to myself, I could have stepped on that.

Over the years I have come to peace with this ginormous insect. Unearthing one while weeding causes the creature to flop over while its rudimentary legs paw the air. They are shocked at the light and you. If you look closely you may see a facial expression not unlike Edvard Munch's The Scream. Some even play dead.

Because of their size, you may think that they are something to be worried about. Not so. Unless you have decided to pick one up and hug it and love it and squeeze it, you will probably not be bitten. Your real worry is how to get it back into the soil without touching that subterranean body. Considered scavengers, they are not generally labeled as pests. Certainly they do munch on roots, tubers and decaying animal matter. Their name comes from their interest in potatoes –sometimes they will nosh on those. But, overall they are not capable of much damage.

The potato bug is flightless. Thank goodness. They are nocturnal and like other crickets are able to make a sound by rubbing their back legs against their abdomen. This is called stridulation. Some say the sound is like a woman or child screaming.  When disturbed, they may make a drumming sound by tapping their abdomen against the ground. Despite their reputation of being passive, the female has been known to kill the male after mating.

In North America, the Jerusalem cricket is found west of the Rocky Mountains. It is the largest insect in western North America. I lost my initial squeamishness for them when I realized how bumbling and unprepared they are for confrontation. Their unaesthetic appearance made me feel all the sorrier for them. It is interesting to note that there are six species that reside in California. One species has gone extinct in the San Francisco area due to habitat destruction. Three other species are considered endangered.

So what became of those two guests that visited on that wet evening? After a bit of coercion I convinced them to hook their bristly legs onto a paper towel and I placed them back out into the night – under shelter, of course.







Posted on Sunday, August 2, 2015 at 1:31 PM

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