Can't tell for sure what it is; but it looks serious, as in phytophera, citrus leprosis, such things. I would cut it off and burn it, just for insurance. Have fun on your trip

More pictures! John, I was afraid of that! Here are some more pictures, including how close to the one of the main branches it is. Also a new area just starting on a smaller branch.

How close to the main trunk should i go? I'll go cut it off for now, but if anyone can chime in with any other things I should do, please help!

Also, should i be letting someone in the county know? Is this something they need to quarantine asap?

No quarantine required. Look up citrus phytopthria on the Internet, and you will find many areas of advice.

Silica, is it pretty obvious that's what's going on?

So I found and cut off three branches that seemed affected, rinsing my saw with bleach in between. One branch had the sap right at the fork, so I sprayed that spot with Bonide, figuring better some burn at that spot than spread. The inside of the branches seemed fresh and green, so that seems like a good sign?

KC

http://ipm.ucanr.edu/PMG/r107100411.html

A little more info and from reading it sounds like your symptoms.

Phytophthora Gummosis

It does, indeed! :( I almost feel like axing the tree and planting something else in its spot. I am so worried it will spread to my lovely and productive lemon right next to it!

PacNorWreck, I'll try and get some! I hope I can apply it during a heatwave. Or else it's gonna have to wait ten days till I get back! Ugh, this is scary!

Hi kcandmilo, it's best applied as a soil drench and it takes a little while to work - it doesn't kill fungus on contact but instead bolsters the plant's natural defenses / allows it to fight off the fungus, and it needs to be taken up through the roots for that to happen.

Oh ok! I'll see if anyone local has it, otherwise, it will have to wait till I get back! Thanks!

Here's another link of information on phytophthora:

http://www.idtools.org/id/citrus/diseases/factsheet.php?name=Phytophthora

Can enter through any wound or bark cracks when water from the ground splash up onto the tree. Also mentions that Phytophthora is commonly associated with root damage done by citrus root weevils.

I've seen a root weevil crawling on my potato plant at night, I'm afraid of it going for my lemon roots. Might be a good idea to check on your trees at night for root weevils if the mold originated from insect damage of the roots.

Is your tree planted lower than your average ground level? From the photos it looks like you made a nice water basin but the tree is sloped deeper into the basin's lowest depression. Most advice for citrus is to sit higher than the basin to let water pool outwards to the outer edges where the branch tips end, keeping the trunk/bark relatively dry. If it pools inwards towards the trunk like a bowl, then the moisture will be too concentrated in the trunk and bark and will create ideal conditions for phytophthora :( It's more likely that th cause of the gummosis is because of that. But I can't be sure from the angle of your photo. You may know all this already but if not, I hope this helps in some way.

kvetchlambkin, I knew none of this! Thank you! There's no water basin, the trees are higher than the surrounding area, and they are planted around a much lower swale created to drain water away from the area and into the water table. (The swale has a french drain that runs 30 feet into the ground to help the water table, and to prevent run off into the creek that runs along by property line. City code.)

However, I have been watering with a hose and letting the water splash on to the trunk, and I've noticed that a couple of areas of the yard seemed moister than I expected. I'll have to check the irrigation lines and make sure I don't have something strange going on.

On an unrelated note, three plants in three different parts of the yard suddenly turned dry and brown almost over night, and died. (A daphne, a oakleaf hydrangea and a patch of azaleas about 30 feet or more from each other). I wondered if something had eaten their roots, because short of being sprayed with roundup, I couldn't imagine what would cause that! I'll look into root weevils.

Tbh, I would rather sacrifice this tree, pull it out, drench the soil and plant something else, than take a chance that it might affect my lovely healthy Meyer that grows next to it!

KC

On the hydrangea side how long have they been in the ground? I got 4 plants from my mom and they seem to hate the heat. The only one that is doing well in my yard has partial shade in the afternoon. It might be worth it for you to dig them up and see.

Bacon, they are 4 or 5 year old fairly established plants! All in a row, doing really well, and then one up and died! I'll take pics today, and yes, dig them up and see what's going on underground!

KC... do you have gophers?

Not usually, John. The grass is fairly undisturbed, and I don't see holes or tunnels any where.

I use gardenweb on my phone so I can't zoom into the photos posted but the second photo of your tree+trunk, is the trunk a darker grey color? Looks like a water mark line on your tree? :(

Is your tree planted along the path of water flow from the higher surrounding into the swale? It could still be encountering water too often if th flow of the swale passes through the tree even if it doesn't pool into it. If that is the case then pulling up that tree may not help your healthy one next to it :( I haven't done much research on swale construction so take what I say with a grain of salt lol there's actually a YouTube channel of someone who moved to a tropical area and is in the process of setting up a homestead and a swale with a citrus orchard surrounding it. It might be helpful to check out the locations of his trees and their distances. He lives in a place with little rainfall though so water damage to his citrus probably wouldn't be an issue.

I'm currently out right now but I'll find and post the link to the guy making the swale a bit later

There IS a dark lower area like a watermark on the tree in question, but it's always had it! I assumed it was the graft line! One of the branches grew out super dark too, and i wondered how that would happen above the graft line!

We get very little rain too, just a month or so in winter, so I'm not worried about super moist conditions generally. I also cut some of the branches that were getting too close to the Meyer.

Here are pics of the general location:

Sorry I don't have any experience with grafts so I can't tell you either whether it was a graft line or a normal thing. From what I've looked up on citrus diseases or molds/fungus is that bark discoloring is usually a bad sign. Especially if the discoloration is darker, white, or generally different from the color palette you see on your tree.

How long does it take before you notice the surface soil to dry out? Does your soil drain well? Even if it is not directly in the swale, if it's close enough it will be more accessible to the moisture and water table. I think even with a lack of rainwater, if the humidity of the air is high then the leaves will not dry out as much which signals the roots that it does not need it to absorb moisture from the soil. So the soil could be staying moist longer than it needs to be. What is the soil like where the lime is planted?

kvetch, I can't imagine that too much water is an issue. We have low humidity and last year was the only year we have had any significant rainfall. I'm fairly confident we drain fast in the area where the trees are planted, even the heaviest storm last winter which drains into the swale empties out fast. (All the house gutters are also directed to the swales.) You got me wondering about the discoloration though, I'll make a new post to ask about that!

KC

KC, What are the raised boxes with it looks like fencing around them? Is that so you can cover them for cold and bug protection? Maybe deer or other animals too? I need to make something like that for at least some of my trees. Your yard looks beautiful.

Cory

Cory, those are my raised vegetable beds. A creek runs along my fence, and my yard is like a truck stop along the freeway for all the animals that travel along the creek. They ate everything I planted, so my friend built me these boxes with mesh panels that lift into notches on the sides.

Enough people have asked me about them, so I have close up pics.

Thank you for the compliment. When we got this house, the yard was nothing but broken concrete and construction debris, so I got a clean slate to work with and chose a drought tolerant, somewhat native, easy maintainance yard. The grass only gets mowed a couple of times a year, everything else mostly only needs seasonal clean up or deadheading. It's not the manicured tidy yard most people have, you have to tolerate some scruffiness, but it feels very natural and park like to me.

Sounds like my kind of yard! I'm looking to fill the bare soils of my parents yard with native flowers both drought tolerant and ones that can handle wet areas where the gutters divert the rain.

kcandmilo if you received the tree with that darker bark already on the tree then I agree, the water probably wouldn't be the issue from what you've described about your rainfall and swale drainage. It's possible your tree already came to you infected or in a condition very ideal to become infected. Someone else who had a similar experience might relate better with your situation :(

kvetch, since this tree has been barely productive, I'm so tempted to get it out, soil drench with the agri-fos and then plant a new one later. Telling myself not to act in haste!

Here's some of the photos from the shrubby side of the yard:

Thanks for the closeup pictures KC. I really enjoyed looking at them.

Wow your garden looks beautiful. I love the unmanicured yet still somewhat organized wild look. You have some nice combination of grasses, colors and heights that look beautifully with each other! I hope the phytophthora doesn't spread to your lemon tree either! It looks like a lot of work went into getting your yard to where it is now. Definitely prune off those dark branches from the healthier looking trunk and maybe cut the dark branch along its length to take a look at how deep the discoloration goes. Maybe you can find something if you search for a different set of phrases that better match your trees' situation! Good luck with your lime!