I don't know but if they are not more than skin deep they will not be a problem. Your lemons look close to yellow and picking time.

Steve

Some sort of fungal infection; probably too late to treat this year. Best to harvest those fruits and examine the inside to see if there is damage to the fruit. Next year, because you live near the coast, I would spray with a good quality fungicide in the Spring, after the flowers and/or treat with a systemic fungicide.

Oh no Vlad I am so sorry. That is heartbreaking after all the hard work you do. I hope that it hasn't affected the inside of the fruit.

Did you pick one and cut it open to see if just the skin is affected? This is sad - I hate seeing sorry and sick citrus. It's heartbreaking after all our work to try and keep them happy.

I don't grow Meyer lemons, nor am I any kind of an expert on Meyer lemons. The picture you show looks like the early/middle stages of a bacterial disease called Black Pit. In the beginning black pit lesions on fruit may be smaller pits or specks that develop into larger sunken spots. The progression of the disease originate as a light brown spot in the rind, and grows to become a large brown lesion and finally turns black. It is a bacterial disease that normally occur under cooler, wet conditions. and lemons are the fruit that is most susceptible to the disease. Actually, I'm not sure if Meyer lemons are susceptible, but they are 1/2 lemon by parentage.

Silica, I am not sure if it is black pit because my understanding is that the bacterium also affects the leaves. The leaves on my tree look healthy.

I cut one lemon in half. The discoloration is limited to the exterior of the peel. It sure smelled good when I cut into it! And it tasted good, too.

I don't know that we HAVE Black Pit (bacterial) in the US; could be; but I just am not aware of it. Several kinds of fungal including Black Spot (fungal); and others. Preventative treatment with copper oil, broad based fungicide, or systemic fungicide generally control fungal problems. At any rate, the interior of your lemon looks fine; and I would certainly enjoy it.

Ugly outside but delicious inside? I consider that a WIN still haha! Plus no one will steal them

You might want to pick the others so nothing spreads to the tree. You might also use a bleach solution to wipe on the peal to kill what ever is on the surface.

I will pick all of them. Problem is that I do not know what to so with so many (about 40) lemons.

You could pick the 10 worst and bleach the others skin. Your tee is worth more than the lemons. Lemonade, extract for cakes and pies. Limoncello

Steve

Juice and freeze? Maybe talk to your wife about some future lemon bars and pies haha!

I wouldn’t have any problem using 40 lemons in a week! It your not as franatical as I am about lemons, I know people juice them and then freeze it in ice cube trays.

Vlad, when the problem is on the leaves and bark, it is not black pit, rather it is citrus blast. A close disease.

Vladimir, do you have a fan going on in there moving the air around really good? And how cold is it getting in there with the leaves wet?

Mike, yes I have a fan on all the time. Lowest temp. is 55 F.

I read on Safer's site that insecticidal soap may mark fruit, so maybe it was the soap that I used in my neem oil mix that caused the damaged fruit.

Could be. I once did that with Safers Soap and mines did the same thing, my Meyer Lemons, because it leaves a residual behind. If that is the case then it is fine. Have you tried to rub it off? Does it come off like tar or dirt? If not then the fruit could of gotten damaged as it was growing like mine did.

By the way, great job with air movement and temps. I find it practically impossible to have disease with the kind of care you give your trees.)

Amanda, good one..lol

The black marks do not rub off.

I was going to ask about a fan too, but Mike beat me to it. Seems like maybe excessive humidity in there? Glad the juice is good!

hobbyartisan I was thinking that too, humidity but it shows on the leaves first before getting to the fruit.

Vlad 55F is your min temp? :O that must be quite the heating bill

Matt, yes keeping the greenhouse set at 55 F is expensive but my trees are happy and produce fruit year round. What temp. would you recommend?

I bet they are all looking great. IMaybe mine just doesn't heat at night that high, not enough power which is ok especially this time of year. I have mine not set but lows are in the 40's. You probably have a much better heater :) do you mind sharing which heater you have?

I have set my heat to 62F

I have a milk house heater (https://www.amazon.com/Patton-PUH680-N-U-Milk-House-Utility-Heater/dp/B0000BYC61/ref=sr_1_1?ie=UTF8&qid=1521258175&sr=8-1&keywords=milkhouse+heaters) and a King heater as back up (https://www.amazon.com/dp/B000PSFRTG/ref=asc_df_B000PSFRTG5405849/?tag=hyprod-20&creative=394997&creativeASIN=B000PSFRTG&linkCode=df0&hvadid=198098764798&hvpos=1o5&hvnetw=g&hvrand=9559277446988489111&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9058140&hvtargid=pla-353659235212). The milk house heater is the primary source of heat but when the outdoor temps dip into the teens, then the King heater kicks in.