But Wait!!!

If you're a fan of cheesy infomercials and large potentially invasive vines that attract hummingbirds and can give you a rash (albeit a fast disappearing one), then this is for you: https://www.hummingbirdvinesoffer.com/

BTW, the vine is Campsis radicans, a member of the Bignoneaceae family (the same family that brought you the Pink trumpet tree, Tabebuia impetiginosa).

Tabebuia's In Bloom Now

You know spring is really here when the Tabebuias start blooming. Native to South America, they do very well here as moderate growing shade trees up to 50-60 feet tall. . Most of our specimens made it through the wind, although one very early blooming tree was severely damaged. We're keeping the tree, but it's not pretty. All that's left is a stump but hopefully that will grow back sufficiently to provide us material enough to make some cuttings. Before the wind snapped it in half you could see it blooming, always several weeks before all the other Tabebuias, behind the wedding gazebo located at the north end of the event lawn. Still the view from the lawn is spectacular, and a smaller Tabebuia located next to the carnivorous plants greenhouse has taken up the slack.

Foot Wide Magnolia Blooms in the Herb Garden

*Magnolia x   veitchii? in bloom in the Herb Garden

Magnolia x veitchii?  being admired by staff. (l to r) Arboretum herb garden curator Theresa Rachau and Irene Chang.

 Located in the herb garden, this large flowering Magnolia is blooming right now. The monster flowers can be up to a foot across, and they have an odor much like peppermint. The identity of this beauty is a little bit of a puzzle, as it was accessioned . It has  some characteristics of Magnolia campbellii (the large bloom and pleasant odor) but was accessioned as Magnolia x veitchii, a cross made by British horticulturalist Peter Veitch between M. campbellii and M. denudata in 1907.

* At first I thought this was Magnolia campbellii var. albe 'Stybing White'; but it turns out that this Magnolia was accessioned before M. campbellii var. alba 'Strybing White''s introduction in 1962. 

Browse Our Magnolia Collection -Beta Testers Wanted

I've published a Google map of our Magnolia collection. Each one of the blue icons is a Magnolia in our collection, just click on it and you'll get a short description and history of each plant. It's cool, but the coolest thing is that you can load this map up on your Google Maps app on you iPhone or your Android phone and use your GPS to find out what Magnolia you're looking at in the field. Try it out if you have one of the above and let me know how it works for you.

View Flowering Magnolias at the L. A. Arboretum in a larger map

Wild and Wooly

When I started this job 14 years ago I'd get lots of stuff in the mail. Sometimes the packages would be dripping strange fluids, emitting strange odors and containing strange life forms. These days with email and digital photography I'm mostly spared these surprises but there are still things that require a sample. The pest below is a good example of this. What you see is a citrus whitefly. Now 'citrus whitefly' is a term for any of three different species of whitefly that currently infest citrus trees.

Sample of citrus leaves with wooly whitefly infestation. 

The sample you see on the left is a lemon tree that has been infested with citrus whitefly. Notice the fuzzy white patches. These patches are the reason I needed to see this sample. When this had been originally described to me it was described as a 'fungus'.

Now of the three whiteflies that infest citrus here this one appears to be the 'wooly whitefly'.

Now if you look closer (the lower two images were taken with a magnifier) you'll notice that the 'fungus' looks more like cotton and that there are what look like scale insects surrounding the fuzzy stuff. These 'scales' are actually the immature (nymphal) stages of the whitefly. These 'nymphs' will eventually cover themselves in a cottony tuft of wax fibers (the 'wool' in the pests common name)  that the exude from their bodies. This wax serves to protect them from predators and it also repels water (that's why most contact insecticides will not control them very well).

Some methods of control that do work are:
1. Pruning the tree to increase air circulation.
2. Spraying horticultural oil solution on the tree. This has to be done during the cool time of year or else the oil spray will damage or kill the citrus tree's foliage.
3. Decreasing the amount of nitrogen that the tree receives. Instead of feeding three times a year feed just once.  If you feed citrus too frequently their sap's concentration of nitrogen goes up. Since nitrogen is the limiting factor in the growth of the pests (they've got all  the sugar they need for energy -what they need is nitrogen to form the proteins of their body tissues) if you over fertilize you're practically sending out an invitation to white flies and pests like them to infest your trees. Use organic fertilizers because their availability coincides with the availability of the natural predators that keep the white fly under control -in other words when its warm outside there are lots of predators to control the whiteflies so that is the ideal time you want fertilizer to be available to your citrus trees.  Do not use fertilizers that are immediately available to the plant like ammonium nitrate and urea (found in commonly available water soluble  fertilizers like 'Miracle-Gro').

For more information on control of this whitefly download this PDF:

January 17th out in the Arboretum

Flowering stalks of the King palm (Archontophoenix cunninghamiana).

Tan, pom-pom like flowers of Acacia stenophylla blooming in the Australian section.

Acacia spectabilis, the 'Glory Wattle', earns its common name. Located in the Australian section.

Acacia merinthophora's distinct arangement of stems and phyllodes (leaf-like stems) gives it its common name: the Zig zag wattle.

Back from Flu Bout; Class Rescheduled

I'm back after a wicked bout with that seemed like the flu. For all of you who missed the class yesterday I'll be holding it next Wednesday, same time same channel (1:30 to 3:00 in my office). I'll be covering Spring bulbs, local fungus (in preparation for the rainy season which is not here just yet), and of course the best of 2012's plant information questions so far.

Here's a cool link; it's the UCR Avocado variety page. The trick is to select at least two varieties that are good for your climate zone and are A and B type Avocados respectively. Having both of these flowering types can help insure a steady and abundant supply of Avocados.

A Rant On Liquidambars

 Our recent breezy weather is bringing out lots of concern about the safety of trees planted next to houses. I recently had an inquiry regarding one tree that should never be planted near houses or any hard-scaping for that matter...and it's not a Ficus.

Liquidambar styraciflua is a tree native to parts of the Southeast United States, Mexico and parts of Central America. It’s called a ‘Sweet Gum’ because Native Americans would chew the tree’s resin like chewing gum.  The tree is not at home here in dry Southern California. Where it's native the precipitation averages 25-35 inches of rain a year. The problem is that it is also a tree that has evolved to survive in rocky, infertile soil in its native range.  This ability to ‘tough out’ those harsh conditions makes it appear to be the perfect tree for Southern California; nothing is further from the truth. With the dry winds and the infrequent precipitation Liquidambars here are constantly under water stress.  They also have the propensity to develop very invasive and destructive roots.  But wait there’s more. Ever since 1998 when a new pest called the ‘glassy winged sharpshooter’ was introduced to California Liquidambars have been infected with a disease called ‘scorch’.  First appearing on Oleanders, this disease is a bacteria that plugs up the water conducting tissues of the plants it infects and causes the shoots furthest from roots to dry out so fast they literally ‘scorch’ where they stand.  This has gotten so bad in parts of Riverside county that it causes the trees to die back to almost 2/3 of their former height, causing them to look disfigured and leading to their removal for aesthetic reasons.

Now also consider that the  chances of damage from the wind toppling Liquidambar  trees is  probably not as great as the chances that the trees roots will damage some structure that the tree is within 10-25 feet of. 

So all this leads me to my final opinion on yours, and every other Liquidambar tree growing in Southern California. Unless your tree is at least 25 feet away from any structure it can damage with its invasive roots, and is surrounded by a lawn (which is the only way it’s going to get sufficient water to remain healthy and tolerate the effects of the scorch disease) I would remove the trees and plant something else.

Links:

Here's an article I wrote two years ago about Liquidambars

Australian Garden Expert Don Burke's List of Trees to Avoid; This Advice Good for Southern California Too

Scorch damage on a Liquidambar leaf

Aquamog Returns to the Arboretum

This whimsical machine is going to clean out all the debris that the winds knocked into the Baldwin lagoon!

The L.A. County Department of Parks & Recreation tree crew guide the large central trunk of a hazerdous tree being removed from behind the Arboretum gift shop.

Work continues on cleaning up the wind mess here at the Arboretum. In this picture tree crews are removing toppled limbs from a large Ficus tree located on the south part of Tallac Knoll. 

Should She Remove A Wind-bent Fan Palm?

Spent most  of the day working on a new GIS system that will allow us to map the 326 lost trees in less than a weeks time -a real improvement over the 5 year mapping cycle that is the norm for our 14,000+ collection. Tomorrow the system gets a field check.

I had a call today from a Pasadena resident who noticed after the wind storm that her neighbors tall Mexican fan palm has a noticeable lean of almost 45 degrees. This is not necessarily a death sentence, as evidenced by the existence of many 45 degree leaning palms on the Arboretum grounds. There was, sometime in the late 1880's a horrific windstorm that blasted the San Gabriel valley, maybe the Arboretum's leaning palms were the result of this storm? At any rate since palms are so resilient you might say what doesn't kill them makes them stronger. Since she related that if the palm failed there would be no great consequence I suggested she enjoy her per-quaky palm.

Queen Anne Cottage (pre-windstorm) showing leaning, but stable Mexican fan palms.