Avocado trees big issue Please help!

[msk0072]

My avocado trees are slowly dying! One by one.
Variety Lamb Hass. Rootstock : Dusa (clonal)
It stars from the main trunk or from the branches and spreads to the rootstock
What kind of disease is that?

[raiders36]

Indeed. It looks like some kind of disease which I don't know. What you can do is to destroy the ones that are affected and move the healthy ones to  a different location on your land.

[msk0072]

I moved them yesterday to a new location in the same area and sprayed them all with copper fungicide. Can it help?
Any advice from SoCal experts?

[simon_grow]

It could be any number of issues including fungal like root rot, phytopthera, sunburn, too much fertilizer. What is the pH of your soil?

Try this technique tha has worked for my friend but first check the pH of your soil and ensure your soil has excellent drainage. Find as many local varieties of avocado as you can get your hands on and plant the seed directly into the ground. Once the seedling is large enough, graft a named cultivar on top. http://tropicalfruitforum.com/index.php?topic=12844.0

This technique really works! My friends tree is growing excellent. If this technique works for you, please post a reply on that thread so that you can help inspire others to do the same. It would be best to find a variety that is Phytopthera resistant. Try to get fruit from a neighbor that is growing avocado as this will at least give you some indication that the tree may be somewhat adapted to the local pH, pest and disease issues.

Simon

[msk0072]

Simon
my first priority is to save the plants. I bought them from a nursery in spain and they were not cheap. They are 2 years far from fruting. I do not thing that the didease is root rot because the rootstock Dusa is one of the best against that. Of course i am not an expert
The storry behind the plants is that 2 1/2 years ago i bought a few plants from the nursery and the were staying at same place and they were from the same variety and  same rootstock  They are already planted and the are doing great, already fruiting. I am thinking the didease came with the plants from the nursery, because 2-3 friends of mine they had the same problem with a few plants on the field. They plants are from the same shipment. My plants were together one next to other and not planted yet so the disease spread to the  plants

[simon_grow]

Hey Mike, the best thing to do is to send out plant tissue samples to a lab to determine what it is. You could blindly go in and use a systemic fungicide but even if you got rid of a fungal problem, if that's what it is, the tree could still die. I've seen pretty much the same symptoms on my friends tree and many other people's trees and that is why I came up with the direct seeding method.

Here is a link to a discussion on copper fungicides. http://tropicalfruitforum.com/index.php?topic=19460.0

Please keep us updated on the status of your plants. Avocados don't like high salinity in their soil and they hate wet feet. Avocados like a pH of around 6.5 if I recall correctly.

Simon

[CTMIAMI]

I have also expedience the same symptoms in some potted trees and one one small tree in the ground. When I pull the roots out usually there is a sick, poor root system. I think it starts in the roots and the roots disappear and it can not support the canopy.  I would up root a dying tree and take a good look at the roots.
My impression is either over watering or fertilizer burn

[Vernmented]

That is a large tree in a small pot. It could certainly be disease but it would be hard to keep those correctly watered. Did you pull them out and look at the roots. I am guessing they will be very rootbound.

[barath]

One of the first things you can try is to give them a bit of shade -- either a shade cloth or move them to a location that gets only an hour or two of direct sun each day.  I've seen trees that look like that recover (after several months) once given some shade.

[msk0072]

More dead plants


The drainage of the soil is very good
Barath : the plants were under the shade of a big olive tree since 6 months. In that place started the problem

Some pictures of the root system. I don't see any bound roots

[msk0072]

One more plants root system. I took the picture after the sunset

[msk0072]

Hey Mike, the best thing to do is to send out plant tissue samples to a lab to determine what it is. You could blindly go in and use a systemic fungicide but even if you got rid of a fungal problem, if that's what it is, the tree could still die. I've seen pretty much the same symptoms on my friends tree and many other people's trees and that is why I came up with the direct seeding method.

Here is a link to a discussion on copper fungicides. http://tropicalfruitforum.com/index.php?topic=19460.0

Please keep us updated on the status of your plants. Avocados don't like high salinity in their soil and they hate wet feet. Avocados like a pH of around 6.5 if I recall correctly.

Simon

Simon, i use the same water since many years. I water different kind of the plants incl avocados. Offcourse i will try to measure ths pH

[barath]

Hmm, not sure I have any other suggestions for you, except to say that avocado trees are pretty sensitive when in containers (and for the first year in the ground if planted from a container).  I've lost a bunch of trees in pots or soon after planting.  I've switched to Simon's approach, which seems to be better in the long run.

[CTMIAMI]

I personally never had much success with those deep pots. I Don t know the reason. The picture of the roots did not looks good to me. A lot of black roots instead of  fresh white feeder roots.  Seems like some king of root rot hard to tell if its pathogenic or environmental. Once that problem starts hard to control,

[Guanabanus]

Aliette and Flanker are different brands of a systemic fungicide that often brings plants back from the edge of death.

[Mark in Texas]

White roots = good. Black = bad.  I have found that avocados don't like tall deep pots (they are shallow rooted as opposed to an oak or pecan tree) and do not like to have their root system disturbed.  Their structure is different, no root hairs for starts.  Having said that.....

Looks like Black Streak, a condition caused by cultural conditions that are out of whack.  I had the same issue on 3 trees, sent off sticks to U. of Florida for tissue analysis (highly recommended) and they came back benign - no disease, no canker.  Here ya go - http://ipm.ucanr.edu/PMG/r8100311.html

Results: 

Comments:    
This sample was analyzed using visual (macroscopic and microscopic) and culture techniques. The sample was plated on selective and general fungal media and placed in a moist chamber to encourage fungal growth.

No pathogens could be observed on, or recovered from the sample submitted to the Florida Extension Plant Disease Clinic. Observed symptoms are believed attributable to insect injury, environmental or cultural stress (sub-optimal growing conditions). Examine the plant site for the possible involvement of nematodes, insects or such cultural factors as soil fertility, pH, soil moisture, etc. Promote optimal plant health through proper fertilization and irrigation.

HOWEVER, I also treated via the soil and foliage (when they had leaves, the trees completely defoliated) with a systemic copper sulfate pentahydrate. I have 2 such products now, same chemistry - Magnabon and Phyton 35.   Remarkably the trees literally came back from the dead and are pushing a lush canopy of healthy foliage.  You need a systemic if indeed there's a pathogen involved.  Here's what a typical branch looked like.  Most had complete die back.



Good luck!

[Mark in Texas]

Aliette and Flanker are different brands of a systemic fungicide that often brings plants back from the edge of death.

Good call!

[Mark in Texas]

Simon, i use the same water since many years. I water different kind of the plants incl avocados. Offcourse i will try to measure ths pH

These are the meters in my toolbox to measure left to right pH, TDS, and brix. The Anaheim Scientific Instruments design and accuracy is excellent in many respects compared to a couple of Hanna's I just shit canned.

[CTMIAMI]

Mark the result from the lab does not surprise me.  The trees I grew in pecan pots did not do well. They were 40-50% smaller that trees in regular 3 gal.
On the Chemicals I would try mono di potasium salts of phosphorous acid  less expensive and does the same job.

[msk0072]

Hi guys,
today i will unpot a healthy tree and take pictures and look in the local market for a systematic fungicide.

[Mark in Texas]

Mark the result from the lab does not surprise me.  The trees I grew in pecan pots did not do well. They were 40-50% smaller that trees in regular 3 gal.
On the Chemicals I would try mono di potasium salts of phosphorous acid  less expensive and does the same job.

Thanks!

Try coating your pots with MicroKote or the Griffin's I sent you.