Xyella fastidiosa in Oleanders

[beastmaster]

Xyella fastidiosa(pierce disease) is really wiping out Oleanders in Riverside, Ca. I have no love for these drought resistant landscape plants my self. But I have noticed something unusual about the disease. It seems to effect the white Oleanders more then the pink ones.
Just a few days ago we removed every other oleander along a fence line. The dying ones were white and the survivors were pink. I notice this a lot. What would cause this resistance in the pink flower oleanders. I would think their genetically the same variety? Beastmaster

 

[jefflovstrom]

Xyella fastidiosa(pierce disease) is really wiping out Oleanders in Riverside, Ca. I have no love for these drought resistant landscape plants my self. But I have noticed something unusual about the disease. It seems to effect the white Oleanders more then the pink ones.
Just a few days ago we removed every other oleander along a fence line. The dying ones were white and the survivors were pink. I notice this a lot. What would cause this resistance in the pink flower oleanders. I would think their genetically the same variety? Beastmaster

Are both types of oleander the same maturity? Seems the more mature the better. It is very common here. Even the sycamores get it but they survive, ugly tho.
Jeff

 

[beastmaster]

Jeff, I'm assuming in most plantings where the white and pink flowered ones are planted together they probably come from the same lot.
This is just an observation I've made and not some scientific fact, The pink flowered ones must have some kind of resistance , I see it time after time.
In your travels remember to look for it some time and see if you notice it where there is a outbreak.
The liquidambers on my street(city trees )are all infected with Xyella. Their in various stages of decline. Probably from tree crews not bleaching their tools. In their defense I doubt xyella was known in Liquidambers back then. Beastmaster

 

[Ed Roland]

The sharpshooter vectors from plant to plant. Pink flowering oleanders probably still harbor the bacteria without showing disease symptoms.

Predisposed by water stress. Diluting the pathogen inside the plant can lessen symptoms.

"We also noted what others had reported as perhaps the most consistent effect of mycorrhizal symbiosis on host water balance: higher transpiration at similar, low soil water potential." (Augé 1989)
http://plantsciences.utk.edu/auge_overview.htm

 

[David (saltas)]

almonds

Almonds have can have white or pink flowers.
The pink flowers are bitter almonds, they have arsenic in them.
This may have nothing to do with it.

Bugs see in infra-red spectrum and can see a unhealthy tree, Bugs attack stressed trees.

 

[Ed Roland]

Almonds have can have white or pink flowers.
The pink flowers are bitter almonds, they have arsenic in them.
This may have nothing to do with it.

X. fastidiosa is Pierce disease in grapes, bacterial leaf scorch in shade trees. Some viticulture experiments to lessen disease symptoms includes mycor inoculation to try and increase water uptake. Systemic oxytetracycline for shadetrees is not an option for grapes. I always recommend irrigation when dealing with BLS.

I think, since the insect vectors feed on xylem fluid, the [cyanide] content of the seed is moot.

Bugs see in infra-red spectrum and can see a unhealthy tree, Bugs attack stressed trees.

Damaging insects know enough to land on a green thing instead of a brown thing but chemical signals probably play a larger role in finding a meal.

Saltas, You guys getting back to normal over there or are things still a mess?

 

[David (saltas)]

Chemistry

Eds advice is good.

cals.arizona.edu/PLP/plpext/diseases/trees/oleander/oleleaf.htm

The almond analogy was just a reminder that different varieties of the same species have slightly different chemistry.
this was a suggestions as to why white flowered variety was attacked and the pink was not. e.g. if the vector is a sap sucker then it may not like the "taste" of the variety with pink flowers. I don't know if flower colour is related to the toxicity in Oleanders

Insects and light spectrum's

The insects seeing in infra-red is one way that insects are better adapted, than us humans, they can tell that a tree is stressed before we can. If the pink flowered variety is local "provenance" and the white is from a different "provenance" then the white flowered variety is less adapted and more likely to be stressed first.
Insects are attracted to the weaker, stressed plants. A plant that has been weakened by transplant shock, improper hardening off, poor nutrition becomes an easy target. The plant’s color changes in the infra-red spectrum that we cant see in the visible light spectrum and bugs pick up on that.
When plants are sick, a) they become physically less sturdy, b) the stems lose the stiffness associated with adequate water retention, c) the outer surface composition changes, and d) wilting softens the plant tissues, making them easier for bugs to chew or suck thus creating holes in the plant.
The essential oils which are in the plant tissues will evaporate in minuscule amounts into the atmosphere through these holes, and at this point we are unable to protect plants from the insects who can be attracted by only a few molecules of their favorite meal. For example, aphids will walk right by healthy, vigorous plants to attack stressed ones.

Ed
The place is a mess and will take months just to pick up all the broken trees, but you can see clean spots appearing.
Plenty of work many are doing it for free I'am one of 500 registered volunteers.
council press release
"Townsville is steadily getting back on its feet as the recovery from Cyclone Yasi continues on the streets, in parks and in backyards across the city. Townsville’s massive clean-up is continuing today with a council and Army crews clearing the city’s roads of thousands of fallen trees.
The council alone has 270 personnel in 35 crews working around the city equipped with 60 chainsaws, 55 trucks, eight semi-trailer tippers, 27 backhoes, eight bobcats and eight front end loaders to cut, load and transport the tree waste.
Lou Litster Park has been set up as a temporary depot and is mulching 120 cubic metres of mulch per hour through two tub grinders. Other units are located at Harvey Range Transfer Station, Stuart landfill and Magnetic Island landfill. Two more are on their way to the city and will be stationed at Jensen transfer station and the suburb of Cosgrove. Each unit produces 60 tonnes of mulch an hour.
Council also has eight woodchippers out on the road and more on their way and has requested additional chainsaws from the State. The Army is also out in force assisting with the removal of trees in a range of locations.
The city’s landfill and transfer sites have also been accepting green waste from private and commercial users logging almost 2400 cubic metres or 177 tonnes in the past few days."

I see more companies on the road each day, many earthmoving companies are getting signed up as "medievalists" I mean "removalists"