All Things Gardening forum: Avocado Pathogen Help

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Grandifolia7
Oct 22, 2017 11:20 AM CST
Hi, I'm hoping to get some help IDing this pathogen. This is a 4 year old potted avocado I grew from seed, and has been doing great until about a year ago when this white/black spot started to slowly spread. I'm in Portland, Oregon and put the tree out in the summer and back inside during winter months.

I didn't think much of it at first but the bark is obviously cracking and its only getting worse, though the progression is very very slow. Possible ailments I was thinking it could be were also sunscald, some sort of freeze damage, or another abiotic factor. It did have some exposure to the sun over the summer but not all day or too much. It has been out during a couple light frosts, but it got worse over the summer when there was no frost as well. If I wash the area down with water, the white comes off but then comes back after a while (a few days time maybe?).

I'm having issues posting pictures, so I'll try to post a couple follow up ones as well. Let me know if you need any other info and what the solution to the problems are too. Thanks in advance for the help!

Thumb of 2017-10-22/Grandifolia7/b2b9d0
Thumb of 2017-10-22/Grandifolia7/458aed
Thumb of 2017-10-22/Grandifolia7/5cfb21
Thumb of 2017-10-22/Grandifolia7/7232bf

Name: Daisy I
Reno, Nv (Zone 6b)
Not all who wander are lost
Garden Sages Plant Identifier
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DaisyI
Oct 24, 2017 3:57 PM CST
Are you acclimating your tree to outdoor sunshine? Its a process that could easily take two weeks. It looks like sunburn to me. I can't see any white.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost

Webmaster: osnnv.org
Name: Gary
Wyoming MN (Zone 4a)
hostasmore
Oct 25, 2017 3:19 PM CST
I agree it is sun scald. It appears to be very much on the top level of the stem and branches.

Grandifolia7
Oct 25, 2017 11:27 PM CST
Thanks for the input! Would it change your opinion if I said in the last picture, that white on the stem in front of my hand wipes away and becomes as dark black as the section above it?
Name: Gary
Wyoming MN (Zone 4a)
hostasmore
Oct 26, 2017 1:14 PM CST
It wouldn't change my opinion. The burn damage can lead to open areas which may allow fungi to attack. Give it some time under favorable conditions to see how much it will recover.
Name: Daisy I
Reno, Nv (Zone 6b)
Not all who wander are lost
Garden Sages Plant Identifier
Image
DaisyI
Oct 26, 2017 6:37 PM CST
That white under your hand appears to be part of the inside of the stem.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost

Webmaster: osnnv.org

Grandifolia7
Oct 27, 2017 1:07 PM CST
Thanks for the favorable outlook, I'll keep a close eye on it while pampering it!

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