Citrus 'Worst' Disease Detected in Hacienda Heights: Can Spinach Come to the Rescue?

Huanglongbing (HLB) early symptoms on citrus leaves. 

Huanglongbing (HLB) disease of citrus, also known as citrus greening disease, has been detected in citrus pysllids and plant material the local neighborhood of Hacienda Heights. HLB is a devastating disease that leads to the death of infected trees and can lead to the destruction of the California citrus industry (it's already destroyed over 40% of the citrus trees in Florida). It looks grim but there may be a glimmer of hope represented by a gene found in spinach by Texas A&M researchers that helps fight off the disease. Unfortunately field testing has just begun on trees modified with this gene, so it may not be available for 10-20 years. Since the disease spreads rapidly (infection in the Florida trees was only first detected in 2005) that might not be enough time to save a good portion of the industry here. However, like many plant diseases it remains to be seen if the climate difference between the humid, topical climate of Florida's citrus areas and the hot, dry climate of California's citrus areas will have any effect on the spread and severity of the disease.

Associated Press Article on HLB Discovery in California and Texas A&M Spinach HLP Resistance Gene Modification

Huanglongbing (HLB) symptoms on citrus.

California Department of Food and Agriculture HLB Press Release

What Do Oaks and the Irish Have in Common?

 This is a Quercus agrifolia, commonly known as a coast live oak, that was brought to my attention by a North San Gabriel Valley resident. The branches of the tree had defoliated over the last several years. The lawn is a year old, but the previous owner had grown ferns under the tree before that.

This tree is a great example of an oak that might be saved. Live oaks are notorious for defoliating under stress. You might wonder, considering the verdant and luxurious lawn that can be found under this tree, what the source of this defoliating stress is? Well consider the verdant and luxurious lawn for one...and the ferns the previous owner grew underneath the oak. Both of these require lots of water compete with the tree for nutrients. But simple competition isn't the only thing. Oomycetes (in particular Phytophtora species ) organisms that are commonly called water molds, are mostly to blame. Related to the organism that caused the Irish potato famine in the mid 19th century, these destructive organisms grow, multiply and thrive in watery environments. A well irrigated lawn is one such watery environment. The film of water that coats the soil particles in moist lawns is enough to allow the swimming spores of oomycetes to infect the roots the oak tree and cause considerable damage -as well as providing a gateway to a more destructive organism; oak root fungus. It's also a good idea to check the drainage of the area around your oak to make sure that any recent construction hasn't created an impairment for the runoff of water from the area.

So what can be done? The first thing is to tear out the lawn underneath the canopy (or the area that would have been the canopy if the tree wasn't defoliated) and mulch the area with shredded bark. Then allow the trees own leaves to build up in a thick layer underneath the tree. If recent construction has impaired water runof, fix it so that water drains away from the area where the oak is planted. Then treat the area with Agrifos according to instructions (Agrifos is a type of fertilizer that has a preventative action against oomycetes). And finally adjust your watering so that you are not watering the tree; natural rainfall is usually enough to sustain the tree. However, additional watering may be necessary in situations where it is a drought year and the original water gathering root area of the tree (which can be an area up to twice the diameter of the tree's healthy canopy) is compromised.

Here is a particulalry good publication that goes over what can go wrong with oak trees.

Carried Away

 It's hard not to get that here when it comes to photography.

Is This An Oak Defoliation Culprit?



Chaperral camel cricket; responsible for a naked oak tree?

  I received a picture of this guy in my email a week back from a local oak tree owner who was finding them on her now defoliated oak tree. Was this one of the infamous 'Gold Spotted Borers' whose occurrence here could spell doom for thousands of our Oak trees? Well, probably not as evidenced by this creatures large hind legs; do they look familiar? Yes, it does look like a cricket and, according to L.A. County Agricultural Commissioner's office entomologist Gavork Arakelian this is a native cricket known as the 'Southern California chaparral camel cricket'. It does eat leaves, but whether it's responsible for defoliating an entire oak tree is questionable. There are other insects that can cause defoliation including the California Oakworm, but many of those are summer pests and are inactive in the spring. Still, a closely related insect in Texas has been known to defoliate oak trees. So is this the culprit? Although I don't have enough information it is possible but not likely  because the Chaparral cricket is omnivorous, it will eat anything,  including oak leaves.

Pad Tours



Holding tablet with picture of work-in-progress at the Madagascar spiny forest exhibit showing; can this work on a sunny day also?

  I just tested an Andriod tablet as an interpretive device today and I was pleasantly surprised. I was giving a tour to a group of about 14 college students and I used the tablet to show pictures from a powerpoint presentation on the history of the Arboretum that I had uploaded to Google web albums (AKA Picasa web albums). The students were able to see the pictures, and navigating through the album was breeze. Now today was quite cloudy so there was no problem with glare -I am looking forward to trying this out on a sunny day and see if slighlty tilting the screen down and away from the viewers will eliminate the glare (should work unless the ground is snow white).

I Get Critters To Identify

 A client brought in this one two days ago. Several of these were found in a bathroom on the floor. At first I thought they were maggots and I wasted a lot of time searching for them, but I did learn a lot about maggots. Then I axed the maggot approach and I finally came up with what they were; case bearing moths (Tinea pellionella). Here's a video of them showing how the larvae extend out of there protective case and drag it along.

The 'cases' are shells of silk they weave for themselves that are sticky; that's why you see all the dust and dirt adhering to them. They eat wool, feathers, fur, hair, upholstered furniture, leather, fish meals, milk powders, lint, dust or paper. There is no shortage of things for them to eat in a bathroom.

Controlling them is a matter of hygiene and environment. They like to hide out and feed on dust and fibers, so keeping baseboards (where these two were found) and other hard to reach areas adjacent the floor clean is important. It also very important to dry clean your clothes if you are going to hang them up for a couple of days. The moths are attracted to dirty wool and fabric. Keeping your house relatively dry also keeps them away. UC Davis's IPM sight has more information here.

A Field Trip for Plant Information Volunteers.

X Chiranthofremontia lenzii, a cross between the Monkey hand flower  and Fremontodendron sp. 

Ten people, including seven plant information volunteers and their spouses, joined me for a field trip to the Ranch Santa Ana Botanic Garden yesterday. It was a gorgeous day and everybody found interesting plants that they'd never heard of before (including me). Here's a link to photos of some of the plants we saw.  We were lucky enough to have Patrick Larkin, the garden's director, speak to us before we began our tour. We were also privileged to have grounds director Joan McGuire (who worked here at the Arboretum as the herb garden curator before accepting her position at RSABG) and tour coordinator Judy Hayami (also ex of the Arboretum) meet us before the tour began.

Field Trip To Ranch Santa Ana Botanic Gardens Wednesday March 7th @ 2pm

I hold monthly classes for all my plant information volunteers on the first Wednesday of the month at 1:30 pm. The classes are usually held in my office, are free, and are also open to members of the general public for free. I give slide presentations (last month we looked at tree damage here at the Arboretum) and go over the most interesting questions I recieve during the the last month. This month we're doing something different.

Between 1:30 and 2pm this next Wednesday (March 7th) we'll all be meeting at the entrance kiosk of the Ranch Santa Ana Botanic Garden (RSABG) in Claremont. Remember you'll be responsible for your own transportation to RSABG, and you'll also be responsible for your admisson (free if you're an Arboretum member -don't forget your card).


View Rancho Santa Ana Botanic Garden in a larger map


Admission:
$8 Adults
$6 Seniors (65+)
$6 Students w/ valid ID
$4 children aged 3-12
No charge for children under 3

If You Are An Arboretum Member You Will Receive a Free Reciprocal Admission, Don't Forget to Bring Your Arboretum Membership Card. 

How To Get Great Shots of the Arboretum

How to Process Great Shots of the Arboretum using HDR (High Dynamic Range) Software

One of the big problems photographing any outdoor scene is the huge amount of contrast you might encounter. If you expose the picture at a high ISO you get more details but your color seems washed out, expose at a low ISO and you get vast amounts of shadow that take away from the image. Now there is software that can take 'bracketed' (two or three pictures taken of the same scene; one at the recommended exposure and the other one or two a step above and/or below that value respectively) The software evens out the tones and keeps the contrast from being too high. It can also compress the tones to make them more colorful and dynamic, but not to the point where believability has to be suspended. Below is an example two photographs I used HDR on to make a single, dynamic and impactful image. 

Shot of aloe section and cactus and succulent section at recommended exposure level (Nikon D5000)

Shot of aloe section and cactus and succulent section at  1 step under recommended  exposure level. 

Composite of above images created  using HDR software. 

Right now I'm using Photomatix Pro for my HDR processing, it's about$90 and you can download a trial version (it leaves a watermark on the image when your done). 

• Stuck In Customs travel photography blog section on HDR photography. 
• Luminence open source HRD software. I haven't tried this but it's free -let men know how it works for you.