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Nursery and Floriculture Alliance

From the UC Blogosphere...

Citrus IPM Guidelines for ACP and FRB Updated!

The UC IPM Pest Management Guidelines for Citrus have been updated for Asian citrus psyllid and Fuller rose beetle.  There are several new insecticides listed and new recommendations for how to manage these pests in citrus orchards.  The main link is and the specific links are:

Asian citrus psyllid

Fuller rose beetle

Posted on Wednesday, July 1, 2015 at 11:57 AM

Big Sycamore Tree... Big Problem?

Help and Advice from the Help Desk of the Master Gardeners of Contra Costa

Client's Request for Information and Advice:

65 year old Sycamore tree
I live in central Contra Costa County and have a very large Sycamore tree in my front yard. I would guess it's height at 40 to 50 feet. It has an 8 1/2 foot circumference, and many large branches have grown over my house. I am not sure how old it is, but my guess is that it is at least as old as the house, which is 65 years old. It was here when I moved in, which was 35 years ago -- and it was very large then.

The tree has received water from the lawn that surrounds it, although I am now cutting back to watering only every two weeks due to the drought, which I understand should be sufficient for the tree. It has not been pruned except occasionally to keep it out of the power lines. Large roots are visible on the surface of the lawn. I believe the only fertilizer it has received would have been when the lawn was fertilized, which hasn't occurred for probably ten years.

Sycamore tree branches over roof
My question concerns the branches that are growing over my house. Are Sycamores of this size safe growing over a house, or should I have those branches pruned back?

I hesitate to contact a tree pruner, as I am not confident that they would give me an accurate, unbiased answer since it would be in their interest to suggest that pruning was necessary.

MGCC's Help Desk Response:
Thank you for contacting the Master Gardener Help Desk.

You are right to be concerned about your tree, especially during the drought. Trees on residential properties can add value to the property, provide a pleasant setting for the house, neighborhood and community, shade from the hot summer sun, and a “sense of place”. There would no doubt be different neighborhoods without our trees. Because of these factors, homeowners taking good care of their trees are usually amply rewarded.

Your Sycamore tree is probably a California Sycamore (Platanus racemosa), a widely planted residential tree for its beauty and shade which can live for over 150 years. While generally easy to get along with, Sycamores do have their problems at times, namely Anthracnose and Powdery Mildew (see Overall though these are usually minor irritants to the homeowner if the tree is properly cared for, e.g. watering to maintain its health, and some pruning to provide for appropriate growth.

However, our research find that Sycamores are known to experience a phenomenon called "Summer Branch Drop". More information about this phenomenon can be found at this link from the Journal of Arboriculture. (

While Master Gardeners can provide advice and appropriate references on the care of your Sycamore, we are not professional arborists, especially for significant concerns such as yours. From the pictures of the overhanging branches, it would seem that an assessment of the health and well-being of your Sycamore by a professional arborist is appropriate. While the cost of professional consultation is not insubstantial, the payback in peace-of-mind and protection of your investment in the tree and house could be substantial. So, in spite of your misgivings about the motivations of a tree service company, we would strongly advise that you have your tree inspected and evaluated by a certified arborist, probably a consulting arborist to provide a neutral 3rd party evaluation. Certification of arborists is by the International Society of Arborists (ISA). Some certified arborists are independent consultants while others are associated with specific tree care companies. While the independent consultant's consultation is probably close to a given fee, you should be able to request an estimate from any tree maintenance company for their proposed work. UC provides some advice on dealing with contractors and consultants at this link (

ISA Certified Arborists in our area  can be found at this link Once on line at the ISA page, to find an arborist in our area, use the Search by location function. Choose United States from the pull down menu, then type in the zip code and radius of interest (25 miles should be more than ample) and search again. This will bring up a list of certified arborists who work in our area as well as distinguishing who that are associated with and/or an independent consultant.  My search found that there are many certified arborists to choose from in our area.

It appears that the tree has been receiving reasonable cultural care. Fertilizing established trees is usually not necessary. Your watering schedule may be sufficient, but we recommend that you speak with the arborist about caring for your tree during the drought as well, especially since you have exposed roots.

I hope that this information is helpful. Please do not hesitate to contact us again if you need further assistance.

Help Desk of the Master Gardeners of Contra Costa

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, June 29, 2015 at 12:09 AM

Fire Safe Landscaping



Fire Safe Landscaping

By Kim McCue  UCCE Master Gardener


Protecting your home and the people in it during fire season is all about creating what CAL FIRE terms a “defensible space”.  This involves removing all combustible materials within a certain distance from your home and maintaining a fire safe landscape.  CAL FIRE recommends contacting your local fire department for specific fire prevention requirements in your area as those details do vary from city to city.  For example, Paso Robles issues very specific weed abatement guidelines depending on the size of your lot, whereas the Five Cities Fire Authority says all combustible, noxious or dangerous weeds need to be no taller than 4 inches.


A fire safe landscape consists of fire resistant plants and/or some native plants, green lawn, or noncombustible materials such as rock or stone.  Plants and shrubs within the first 30 feet or more from your home should be irrigated and low growing.  Cal Fire actually suggests the first 100 feet from your home should have no trees or shrubs over 18 inches in height.  If there are already trees and shrubs within that area, branches should be at least 10 feet from the roof and chimney, trees should be spaced at least 10 feet apart, shrubs should be well spaced, and all should be pruned regularly. The goal is to prevent “fire ladders”, which are continuous paths of vegetation that carry fire from plant to plant and then to your home.


When selecting plants for the fire safe landscape, look for those that are low growing and high in moisture content. Good examples are yarrow, alyssum, lavender, creeping rosemary and of course, succulents. Plants to avoid are those high in oil or resin content, those with papery or peeling bark, and plants that retain a lot of dead or dry material. Examples of plants that fall into this category include pine, eucalyptus, manzanita, California sagebrush and juniper.


An excellent, easy to read, yet detailed resource on this subject is University of California ANR Publication 8228, “Home Landscaping for Fire”, which can be found at:  



Posted on Sunday, June 28, 2015 at 9:07 PM

Daily Life For Master Gardeners

A Simple Plant: Dusty Miller

By Andrea Peck



Dusty Miller (Senecio cineraria) comes with a plain name and at the point-of-purchase, a plain demeanor. I'm not sure why I bought the six-pack two years ago—I think I had been swayed by an article about white plants or maybe it was fall and I thought oh, these may look wintery in a few months.

Two years later I couldn't be more pleased. The diminutive seedlings are grown and lush. Tiny yellow flowers top their wooly grey foliage. They are so large now that they completely cover an entire corner around a plum tree (that is badly in need of pruning, I might add). They are quiet in their exuberance, but if you look closely, that is them leaning happily into the pathway.

I can attest to the fact that Dusty Miller is easy to grow. I can be stingy with water and sometimes my life takes precedence. The garden does not come first. But, this little trooper stuck with me. In some areas, where frost and cold are extreme, Dusty Miller is considered an annual. On the coast, it can grow perennially—after the second year, the plant will flower. Dusty Miller prefers a sunny spot.  It is drought tolerant, but like most plants, you'll need to send it a little drink when circumstances border on parched (currently we are using laundry water in that area).  They prefer rich, well-composted soil. Depending on the varietal, this plant can grow up to 2 feet high and spread up to 12 inches. Often you see Dusty Miller in industrial or commercial settings—here they are groomed to maintain a prim form.

Interestingly, I have read that many gardeners pinch back the little yellow flowers. In fact, this plant seems to have an overabundance of articles devoted to pruning it. Personally, this formal approach confuses me.  I did read that the flowers take energy from the “lovely silvery foliage,” but don't flowers take from all “lovely foliage?” Grown hippie-style these are fun, rumbling plants that are only better large and flowery.

Dusty Miller does not appreciate soggy soil. But, at this stage of the game, who has any of that? The plant requires light feeding; 10-10-10 fertilizer is sufficient. Because the Dusty Miller does not like to be over-fertilized, a dose of compost at regular intervals is another option. You may have gotten the feeling that I am opposed to cutting this plant back, but if it starts to look leggy and ungainly, by all means prune it down. You will be rewarded with a bushier plant.

Dusty Miller is resistant to both deer and fire (and fiery deer, I suppose). Best of all, hummingbirds, butterflies and bees are attracted to this unusual plant. It is possible to propagate Dusty Miller from stem cuttings. And who couldn't use more of this easy and appealing plant?


Posted on Sunday, June 28, 2015 at 8:47 PM

Those Finicky Ficus!!!

Advice from the Master Gardeners of Contra Costa's Help Desk

The Client's Concerns and Requests:

Ficus benjamina
"waxy" deposit on leaf
I have a Ficus benjamina which has white waxy globules on the base of many of the it's leaves (see picture right). I've had this tree a long time and I'm concerned it's somehow diseased. I don't want to lose it. Could you tell what the globules are please? What concerns I should have about the health of the tree?... and some guidance on keeping the tree healthy and alive?

Response from the MGCC Help Desk:
Thanks for bringing the Ficus benjamina (Weeping Fig) leaf samples and photos into the MGCC office this morning. Having a sample made it easy to see the white sticky globs at the base of each leaf. When we looked at the leaf under the microscope, there were no insects present on the leaf or under the white waxy substance. We also looked at another Ficus growing in our office and found that it, too, had the same white sticky globules on the base of each leaf.

Ficus benjamina
potted indoors
After further research, we discovered that there are several cultivars of Ficus benjamina which have a dark black “wax” or “phenolic” gland at the base of each leaf which secretes latex to attract fig wasps that pollinate the tree in nature. The white substance you are seeing is a latex leakage which crystallizes when exposed to air. The reproductive systems of species in the genus Ficus are unique. A University of Hawaii article on Ficus benjamina explains that each species of Ficus has an associated species of agaonid wasp and pollination can only occur when that specific wasp is present. Your plant is trying to attract a tiny little pollinator wasp which in all probability has not been introduced to our area. I don't believe that the white substance you have is anything to worry about. If you are concerned about the aesthetics of the white spots, you might try wiping and/or washing them off. Curiously I noticed that the heat of the microsope caused them to liquefy and drip off! For more information on the special leaf gland on some Ficus cultivars, see the University of Florida article

You also mentioned that you might also have a sticky substance in the middle of the lower surface of some of the leaves. If these are in locations where they wouldn't be a drip from the leaf gland of possibly a nearby leaf, it is possible that you might have scale or another sucking insect. As I mentioned, we didn't see anything under the microscope. You might want to examine your leaves, and contact us if you do see any signs of scale or other insect. (Although not a UC guidance document, the UC references cited in the article on Ficus Benjamina Pests” at would be the primary UC guidance MGCC would use to determine appropriate care if there were pests on your Ficus.)

Ficus are notoriously finicky about water, light, and transplanting. From the picture you provided, it looks like you have a nice light filled location for your tree. Because the back corner is dark, it is a good idea to frequently rotate the pot. You mentioned that some of the leaves are turning yellow. Yellowing leaves can be a sign that it is either getting too much or not enough water. (We did mention that Ficus are finicky?) You said that you water your plant once a month, just until runoff, and that the roots are “tight”. It may be that the root ball is very compacted and not able to take up enough water because the water is quickly running through the pot. One method of helping to get the root ball to take up water we would propose would be that several times a year when you water the plant, completely submerse the pot in a tub, bucket or pot of water. Leave it for several hours, giving the rootball a change to become fully saturated. You will want to drain off any free flowing water when you remove your plant from the tub/bucket/pot. After that continue watering as usual.

Regarding repotting, check the roots of your Ficus tree to determine if/when it is time to repot the Ficus. If the pot appears crowded with roots and there is little soil left, your Ficus has probably become root-bound and needs to be repotted. When repotting, after removing the tree from the pot, brush the soil away from the root ball to assess how badly root-bound the Ficus has become. If some of the roots have begun to circle around the ball, carefully unwind them with your fingers. Gently separate the roots in the root ball, releasing any dirt that may have been clogging it. Cut off any dead or rotten roots using a small pair of gardening scissors or pruning shears. If any of the roots have begun to grow through the drainage hole in the pot, prune these back as well. Select a new pot that is 1 or 2 inches wider in diameter than the old pot. Fill the bottom with several inches of fresh potting soil, place the tree into the pot, and backfill with new potting soil to cover the roots and stabilize the tree. Often when their environment is changed, whether a change in water, light, rotating the plant, or transplanting there is a chance the Ficus will drop its leaves - but in time they should grow back.

Feel free to contact us if you have any additional questions.

Happy gardening with a great indoor plant.

Master Gardeners of Contra Costa's Help Desk

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, June 22, 2015 at 12:07 AM

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