I forgot to mention, I'm in Redwood City, which is between San Francisco and San Jose. Here's a zoomed out picture of the tree.

Some of the worst leaves

I love that barrel for a citrus tree I am doing half drums and love it. I don't know how to help you but some one here will

Barrel power!!!! Steve

being a tree guy.. rather than a citrus expert ...

tell us about the media in the pot ...

when i grow trees in pots.. its about half bark chunks ...

yours looks like all high peat potting soil ... which might not favor a tree ... and though it might drain.. it still might be HOLDING much more water.. than the tree wants .....

a stressed plant.. suffers all kinds of problems.... but solving an effect.. may not address the cause ...

i also wonder.. when this started.. and if it was shortly after transplant ... was it bare rooted... was it hardened off to full sun .. etc ...

it is not uncommon ... for recent transplants.. to SHOW damage... when the heat of summer really sets in ... the insult to the root mass being long ago.. many peeps are again.. reacting to the effect.. rather than searching for the cause.. which could have been back then ...

again.. as a tree guy... i would not have fert'd a recent transplant tree for the first year .... especially.. within a month or two of transplant... you are already on feeding #2 ... try to keep in mind.. they are not children ... and do not need to be continuously fed ....

though i fully understand.. that fruit peeps do things much differently ... so all i am doing.. is raising variables which come to my mind ... and look forward to how citrus growers might differ ...

ken

Did a quick search and it doesn't look like brown spot, canker or scab. Likely insect damage but there may also be minor elements deficiency (orange/yellowing in leaves). My suggestion is alternating (minimum 1 to 2 weeks apart) citrus nutritional spray, neem and copper fungicide. Both neem & and copper are fungicidal, but neem is also effective on a number of insects. However, the damage is still very minor so you may want to start with the nutritional spray and closely observe what visitors your tree is entertaining :)

Disclaimer: I'm SE FL Zone 10. I have key lime & meyer lemon (both potted). I had leaves on the meyer like yours in the winter. Now I'm doing leafminer control (as if!)

Good luck!

Here is a link that might be useful: canker pics

Sorry! Meant to add, spray very late in the day. This minimizes damage to leaves and pollinators. I didn't realize this til recently. Learn something new every day :) Good luck!!

It looks like the corky blisters that form on lesions caused by edema. I really see no indication of insect issues at all.

The yellow blotching is a bit worrisome. Are you using a specialty fertilizer for citrus? (Ken....your 'not children ' analogy doesn't belong here. Citrus are heavy feeders.)

I would take your images and some of the affected leaves to your local Extension office (UC Cooperative Extension) .

Thank you for the replies.

Fertilizer: I'm using Vigoro's citrus and avocado 6-4-6. I've been fertilizing quarterly, but just read the new package and it says I should do it monthly during this time of year.

I would expect that would impact the yellowing--I still don't understand the brownish red spots. I don't think I'm overwatering--the pot drains too well, if anything.

This post was edited by Peter112 on Sun, Jul 27, 14 at 19:05

The leaves show a light green: actually you need more nitrogen in your fertilizer.