Do you have oleanders? If so, you might have heard of a fatal bacterial disease called oleander leaf scorch that affects oleander shrubs.
This disease is slowly spreading and I have been seeing it more often when I visit clients.
I wrote an earlier post about oleander leaf scorch, its signs and how it affects oleander shrubs, which you can view here.
Earlier this month, I visited another client whose entire backyard was surrounded by tall oleander shrubs that were quite mature. She suspected that her oleanders were starting to show signs of oleander leaf scorch and it turns out that she was right.
Her suspicions began when she noticed browning of her a few of her oleander shrubs that began this spring and was worsening as summer progressed.
It’s important to note that browning of oleanders doesn’t necessarily mean that they are infected with oleander leaf scorch – browning can be caused by any number of problems from drought stress, salty soil or other excess minerals in the soil.
However, a closer look at the foliage showed some of the characteristics of oleander leaf scorch disease with the outer leaves and tips turning brown.
This occurs because the bacteria rapidly multiply, blocking the vascular system of the plant.
These browning tips are also a sign of oleander leaf scorch, but this particular sign can also indicate high salts in the soil.
Even if you see only a few leaves affected, the entire shrub is infected and will die within 3 – 5 years. Because this disease is spread by a flying insect called a sharpshooter, not all oleander shrubs in a given area may be affected as it hops from bush to bush. However, these insects carry the bacteria in their saliva and spread it to each oleander shrub that they feed from.
While I was able to tell my client that her oleander shrubs likely were infected this disease, the only way to confirm the diagnosis was to contact her local cooperative extension office and send in some leaves from her oleanders to be tested.
If the test comes back positive, she will need to remove all of her oleander shrubs. While they will live 3 – 5 years after being infected, they will turn brown. The most important reason for removal is to help keep the disease from spreading to other oleanders in the neighborhood.
For more photos and a detailed description of this oleander disease as well as a suggested replacement plant for oleanders, read my previous post, “Plant Disease: Oleander Leaf Scorch”
https://www.azplantlady.com/wp-content/uploads/2015/04/ManganeseDeficiency5-1.jpg7681024arizonaplantlady@gmail.comhttp://www.azplantlady.com/wp-content/uploads/2018/10/favicon.pngarizonaplantlady@gmail.com2015-04-30 21:23:002022-10-26 03:49:22Reading The Leaves: Diagnosing Common Plant Ailments
Love them or hate them, oleanders have a firm foothold in the desert landscape where they are usually seen creating living green ‘walls’ in order to provide privacy.
Their popularity is due in large part to several characteristics:
– Their evergreen foliage provides the rich, dark green color that many miss living in the desert.
– Oleanders are easy to grow, with little to no fertilizer and are drought tolerant once established.
– They add beauty to the landscape spring through fall with their flowers.
While the popularity of oleanders is still holding on, there is a fatal disease that affects them that has made its way from California and is now being seen increasingly in Arizona.
Oleander leaf scorch(Xylella fastidiosa) is a bacterial disease that plugs up the vascular system of affected oleanders, eventually making the movement of water throughout the plant impossible over time.
This disease is spread by flying insects, called sharpshooters. These small insects (1/4 inch long) become carriers of the disease when they feed upon an infected oleander. Thereafter, they spread it to every other oleander they feed upon.
Oleanders in Southern California were first diagnosed with the diease in the early 90’s and it was just a matter of time before it spread to Arizona.
Advanced stages of oleander leaf scorch
Oleander leaf scorch was first diagnosed in Arizona in 2004. Its spread has been slow, but inexorable.
I have seen several cases of this disease during landscape consultations, including one that I did yesterday.
The homeowner had a very large oleander hedge that was over 20 years old, which provided privacy from his neighbors.
What may look like some browing leaves in this small branch is one of the classic symptoms of oleander leaf scorch.
Oleander leaf scorch
Close up, you can see the brown, outer leaf margins, which is characteristic of oleander leaf scorch. (Not to be confused with drought symptoms, which cause discoloration of the middle of the leaf).
As we continued to walk along the row of oleanders, the infected oleanders were interspersed between healthy ones. The reason for this is that the nature of flying insects is that they hop from one plant to another, but not necessarily the next plant – they may fly 3 shrubs away before feeding again or to the next yard or block.
Symptoms of oleander leaf scorch
This oleander showed another type of browning symptom of oleander leaf scorch with the tips looking ‘scorched’.
It’s important to note that salt burn resulting from drought or shallow irrigation can cause similar symptoms as shown in the photo below:
Drought-stressed oleander leaves
Note the middle of the oleander leaf is affected in the case of drought stress. While unsightly, the oleander pictured above, does NOT show signs of oleander leaf scorch.
Initial signs of oleander leaf scorch.
Back to the oleanders showing signs of oleander leaf scorch – by looking closely at seemingly healthy oleanders, I could see the beginning of symptoms with lighter green alongside darker leaves. The signs of the disease don’t show up all at once in the beginning. Often, it starts out with a branch here and there showing signs initially that will gradually progress throughout the entire plant.
It’s important to note that once an oleander has been infected with this disease, the entire plant has it – not just the branches that initially show the first signs.
Lower leaves showing the beginning symptoms of oleander leaf scorch.
So, what is the treatment for oleander leaf scorch? Sadly, there is no cure and it will eventually kill oleanders over a 3 – 5 year period once infected.
Some experts recommend pruning out affected branches to improve the appearance of infected oleander shrubs for the short term. But, they will die.
I recommend removing infected oleanders right way to help keep the disease from spreading.
Personally, I have seen the disease affecting large, old oleanders in North Central Phoenix and in the Arcadia area. It’s simply a matter of time before I will see it in outlying areas.
Initial signs of oleander leaf scorch
Consult with an expert if you suspect that your oleanders are infected. Problems with irrigation, nutrient deficiency and salt burn can mimic some of the symptoms of oleander leaf scorch and a horticulturist or other landscape expert can help you rule out other causes. Ultimately, positive identification of oleander leaf scorch can only be made by a lab tests through your local cooperative extension office.
Can you can simply get rid of infected oleanders and start over with new ones? The anwer is, “no”. The reason for this is that the disease is already present in the local sharpshooter insect population and it is only a matter of time before the infect your new oleander shrubs.
I recommend using hop bush (Dodonaea viscosa) as an alternative to oleanders. It is evergreen, recommended for use near pools, makes a great hedge, is drought tolerant and attractive.
For more information on oleander leaf scorch, you may want to check out the following links:
I hope your day is off to a great start! I’m off to the Desert Botanical Garden’s spring plant sale. I just hope my car has enough room to fit all the plants I will want to buy 🙂
Have you ever looked back at your calendar and wondered at how you ever got everything done while still remaining somewhat sane?
I have…
Oh, I knew ahead of time that it would take a small miracle to get through the 30 days, starting with Halloween.
At this point, I’d like to apologize for the lack of blog posts, but in my defense, I was lucky to be able to remember to feed my kids (just kidding).
Seldom, have I looked forward to December as a time where I will be less busy, but in comparison to what I’ve done the past month, it should be a breeze.
It all started with our annual Halloween celebration, which is held at our house.
I spent the day making ghosts (half a Twinkie dipped in white chocolate), black spiders (mini chocolate donuts with chocolate dipped pretzel legs) and candy corn rice krispy treats.
The entire family came over for dinner and trick-or-treating, including my granddaughter, Lily, who dressed up as Sleeping Beauty.
Two days later, we had an even larger group of people gather at our house for Lily’s birthday party – she turned 3!
Lily is seriously into princesses, so there was a lot of pink in the room.
I made her a princess cake, which went along with her favorite cake pops.
In the week that followed, I continued my work with a local golf course, where they are removing 30 acres of turf in favor of landscape areas filled with drought tolerant plants.
The areas of turf being removed are largely out of play in this parkland style golf course. Not all 30 acres are being removed all at once – instead, the grass is being taken out in smaller sections.
While a lot of my time was being spent at the golf course, I spent two days selling handmade items at a large holiday boutique.
Now, I’ve never sold anything at a boutique, but this past summer my mother, who is extremely talented, asked my sister and I to do it with her. I knew that it would be tough, since November is one of my busiest months since I spend most of my time outdoors consulting on landscapes. But, I really wanted to do it, so I used some of my down time this summer to make some things.
Xerigraphica air plant in a terrarium
The items we sold were made using sustainable, recycled and/or repurposed items.
Air plants in terrariums were a big hit.
We also had hanging terrariums filled with air plants. I made bird houses from gourds, many of which we grew in our gardens.
My sister made Christmas ornaments using seed pods from a variety of trees, including these little snowmen made from the seedpods from the Texas Mountain Laurel (Sophora secundiflora) tree.
We sold out of a lot of items and I must admit that I had so much fun. We’re already planning for next year.
Back in the garden, I was asked to consult on a landscape where a Brazilian Pepper tree (Schinus terebinthifolius) had suddenly died
If you look closely, you’ll notice that the leaves are still on the tree. Also, two of the Texas sage shrubs, underneath the window, were also starting to die.
The homeowners were understandably concerned. It didn’t take long to diagnose a case of Cotton (Texas) root rot. The classic signs are plants suddenly dying toward the end of summer and retaining their leaves.
Some plants are more susceptible to root rot and Brazilian peppers top the list. The solution to this problem is to remove the affected plants and replace them with plants that are resistant to root rot. Trees that are resistant include desert willow, mesquite and palo verde.
Some of you may remember that we welcomed a new yellow labrador puppy into our family in September.
Polly is growing fast and although she gets into trouble now and then, she is doing great!
Last weekend, was a day that I had long been waiting for…
My second-oldest daughter, Rachele, is expecting her first child – a boy.
She came home from her Navy base to celebrate her birthday and baby shower, which were on the same day. Rachele had been looking forward to this day when her family and friends would celebrate with her.
But, the day didn’t go quite as planned…
That morning, I was busy getting the house and food ready for 50+ people when she walked out of her room with tears in her eyes to tell me that she had been up all night being sick to her stomach.
We didn’t have time to cancel, and she was determined to make it through the shower.
It was obvious to all that she didn’t feel well, but she did get through the shower without having to leave. However, as soon as everyone left, she got sick to her stomach again.
Needless to say, the rest of the day was spent in bed with a large bowl ;-(
Thankfully, it was only a 24-hour bug and she was up and feeling much better the next day.
Now, you’d think that that was the end of my busy month – but, no…
We were hosting a large family reunion for Thanksgiving just days later!
My mother spearheaded the family reunion and asked my sisters and I to help her with it.
I was tasked with making centerpieces using old family photos AND more importantly, making food for 54 people.
Our family started out in California and hasn’t spread very far – we all live in either Arizona, California or Washington.
We gathered together, on the eve before Thanksgiving, for dinner. My mother didn’t have enough room for 54 people inside her house, so she rented tables and we ate inside the garage.
As I mentioned earlier, I made a lot of food for our reunion, which lasted 3 days. I traded the busyness of work for working in the kitchen. I contributed two batches of meatball soup, 4 loaves of artisan bread, 2 batches of toffee bars, 6 loaves of pumpkin bread, 2 carrot cakes and an icebox birthday cake to our reunion.
For our Thanksgiving meal, we searched high and low for a place where we could purchase a hot, Thanksgiving meal. It wasn’t that easy – grocery stores will provide you with a meal, but you have to pick it up the night before and heat it up on Thanksgiving day. Same with some restaurants. But, we did find that Cracker Barrel does provide ‘to-go’ Thanksgiving dinners – it was really delicious!
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And so, that is a brief synopsis of the past 30 days. I am happy that I survived with my sanity intact – mostly 😉
I hope you enjoyed a very happy Thanksgiving!
I have lots to share with you in the upcoming monthy on a variety of gardening subjects including some really cool garden accessories.
https://www.azplantlady.com/wp-content/uploads/2014/12/IMG_0892-1.jpg7681024arizonaplantlady@gmail.comhttp://www.azplantlady.com/wp-content/uploads/2018/10/favicon.pngarizonaplantlady@gmail.com2014-12-01 13:30:002022-10-31 00:50:12Twinkies, a Princess, Turf, Seedpods, Root Rot, a Puppy, a Shower & Thanksgiving
Most of my job as a horticulturist and garden writer is fun.
But sometimes, I have to be the bearer of bad news.
Last week, I was called to a home where the homeowners were worried about one of their citrus trees. Although I am a horticulturist, I am also a Certified Arborist, which can also be very helpful – especially when I am dealing with trees.
There was a large lemon tree in their front garden. They were concerned because they had some branches dying back and wanted to know what the cause was.
So, I stopped by and took a look at the lemon tree. At first glance, it looked fine – the homeowner had had the dead branches removed.
But, I had to look more closely, which meant getting close to the interior branches and the trunk.
What I saw in one of the remaining branches wasn’t good…
Can you see that the branch on the left is missing bark and is colored black?
What is this you may wonder?
Sooty Canker.
Sooty Canker is a fungal disease that infects many different species of trees including citrus. It spreads through fungal spores. The spores enter the tree through damaged areas on the branches or trunk, forming lesions and eventually causing the bark to peel off.
It is called ‘sooty canker’ because of the black color of the fungal spores. The branches almost looked as if they have been scorched by fire.
In this case, the lemon tree had experienced severe frost damage 1 1/2 years ago. Frost can cause splitting and other damage in the bark. Sunburn damage can cause similar problems as well. The fungal spores enter through these damaged areas and begin to grow.
If only branches are affected, they can be pruned 6 inches to 1 ft. below where you see evidence of the sooty canker. Pruning tools must be disinfected with a 20% bleach solution to keep the disease from spreading between each pruning cut.
I was hopeful that I could tell the homeowners that all they had to do was to prune the affected branches.
But that was before I looked down at the trunk…
The entire trunk was infected with sooty canker. Unfortunately, this almost certainly means that the tree will die.
In this case, the tree should be removed to avoid spreading it to other trees.
I hated to tell the homeowners that they would have to have their tree taken out. Especially after they told me how much fruit they had enjoyed over the years from this tree.
After I told them the fatal diagnosis of their lemon tree – I offered to look at their other four citrus trees. I wanted to make sure that they weren’t infected as well.
Well, the good news was that their Meyer lemon tree was healthy.
The bad news was that their two orange trees and pommelo tree were all badly infected with sooty canker.
Did I mention that I hate being the bearer of bad news?
I must say that the clients accepted the bad news very well.
In fact, they said that they had gotten tired of picking up dropped fruit AND that one of them couldn’t even eat citrus any more due to dietary constraints.
They will be removing their five infected citrus trees while keeping a close eye on their disease-free Meyer lemon tree. At the first sign of a lesion, they will prune it away to help keep it safe from infection.
Guess what?
They asked me to return in spring to design a new landscape area in place of their citrus trees. I like being with people who see things as “a glass half-full”.
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If you suspect that your tree has sooty canker – have a professional confirm the diagnosis and discuss with you the treatment options. If the trunk is not affected, you may be able to save your tree.
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This past weekend, I had a special helper accompany me on one of my landscape consults….
My son, Kai.
He has never expressed any interest in going with me before – but I think he was bored and his best friend (who lives across the street) wasn’t going to be home.
So, Kai offered to come with me and be my ‘photographer’.
As I was talking to my clients, Kai would take photos of certain plants, landscape areas or problems, which I would later include in my report.
He caught me gesturing to this evergreen pear tree, above.
Kai also took some good close-ups as well…
Salt damage from lack of deep watering.
Manganese deficiency in citrus tree.
Kai did also take a few photos with me in them, but he neglected to press the ‘skinny button’ on my camera so I elected not to include them in this post. (Okay, I know that a ‘skinny button’ does not exist on a camera, but I wish someone would invent one, don’t you?)
As our consult progressed to the backyard, Kai was no longer taking pictures.
Instead, he was finding himself in some of the photos I took….
Meeting my client’s new chickens.
Swinging from rings in an old citrus tree.
Kai and I both had an enjoyable time. The clients were very nice people who had a beautiful landscape.
I hope that Kai was able to see more clearly what I do for my work, (besides writing blogs and articles).
But all he said on the way home was, “Can we get some ice-cream?”
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