Growing canker on plum and nectarine trunks

[howmanyds]

I have a small back yard orchard, most of which was planted in May, nearly two years ago, from 15 gallons (except the nectarine which was planted from a 5 gallon that had been sadly neglected for two years and had roots coming out of its container). I'm in Murrieta, an hour north of San Diego, on a hill with plenty airflow; there is an occasional freeze, including a once-a-decade snow we just had the day before New Year's this year, and temps above 100º for 3+ weeks out of the summer.

I'm something of a gardening newbie so I've made some devastating oversights in my journey towards being a backyard farmer.

What the kids and I thought several years ago was an interesting gooey deposit on my nectarine, maybe from a bug secretion, must have been the beginnings of a bacterial canker, if what I've read is pointing me in the right direction. I don't remember how many seasons I've noticed the sore on the trunk, maybe just one (probably two) or when I noticed that the Satsuma plum had one too, but I always expected the trees to heal over the sores and end up with an interesting knot to show for it, so I didn't do anything about it until now, because the sores are so much bigger this year. They're on the southwest side of the trees, so presumably they began as sun damage.

1) Is there anything I can do about the trees now that the wounds are approaching 180º of circumference? I've finger-rubbed away all the loose sappy stuff and inner bark bits.

2) What should I be putting on my pruning cuts for nearby trees (including a plumcot about 20' away) to resist infection?

3) Can I cut these cankers out since we're going to have 80º weather for at least the next week?

4) Should I paint the trunks of any other trees in my yard? I've never done this and it seems daunting/scary to me.

5) Should I worry about the peach tree sores in the last picture that I just noticed on its crotch?

Not counting the potted citrus, I have six trees in parallel lines on each side of the flagstone path towards the fountain. On the left from front to back: granny smith, the nectarine in question, fuji. On the right from front to back: the giant babcock peach in question, sugar pear, and the satsuma plum in question.

nectarine

satsuma plum

babcock peach

[howmanyds]

Interestingly, my nearby potted plumeria has the same problem, also on the southwest facing trunk.

[applestar]

They look like some kind of injury. I wonder if the location of the irrigation is related.
If there are more water available on one side, would the bark split? --- if sprinkler wets the bark, moistened bark could undergo wet-dry cycles... Or if the water is only applied to the earth via drip irrigation, the one side with more moisture may grow more/swell more (=larger cells with thinner walls).

It could also be something has nibbled on the bark or they could have been weed whacker scars.

Canker/gummosis on the fruit tree branches -- I have them on my European prunes and one nectarine is particularly susceptible to brown rot of the fruits. I asked about it before so I'll dig up the link to that thread.

[applestar]

Haven't found my thread yet, but found this advise from JONA -- FYI :
Subject: Plum Tree

If you have to prune any of the stone fruits....plum, cherry, etc. then it is best done when they are in full sap run.
ie. In high summer.
This gives them a far better chance of avoiding Silver Leaf and Bacterial Canker as the oozing sap will help fight off infection through the wounds.

As Hendi says...they should never be hard pruned if possible. It's far better to tie down stray branches into vacant space as this acts as a sap slower as well as getting the wood into the sunlight.


It pays on young stone fruit trees to spend the first few years training branches by tying them down so that the trees natural vigour to reach for the sky is restrained and the trees get into good cropping quickly.