We have a lemon bush in our front yard (I live in Gardena, Los Angeles County, CA) which has recently suffered some kind of disease or blight: The lemons are mostly green, but (after 12 years) some of the lemons that are otherwise still green have large yellow spots on the south side, and in the center of the yellow spot there is a “bad spot” about the size of a quarter. Can any of the Teeming Millions tell me what is wrong with them? Thanks very much.
They have “bad spots” about the size of a quarter.
Any more easy questions?
(Sorry, I couldn’t resist.)
“Vandelay!! Say Vandelay!!”
“Lemon tree very pretty, and the lemon flower is sweet / but the fruit of the lemon is impossible to eat.”
– Doesn’t help Dougie much, but I couldn’t resist the opportunity to quote Peter Yarrow (as interpreted by Trini Lopez)
Peter Yarrow, good folkie musician though he may be, is incorrect. Lemons (at least those that do not share the bad-spot disease of dougie-montie’s lemons) are far from impossible to eat. I probably eat 2-3 dozen per year, sliced in half and salted.
Limes are even better 
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Dougie: I could send your question over to my Gardening mailing list (there are a lot of knowlegeable people on that list). However, i would need to know a little more detail about the “bad spot”. What color is it? Is the spot surrounded by a different color? Does it look downy (which would indicate fungus probably. Have you cut one of these lemons open? If so, what does the inside look like?
Where I come from, those are called ‘limes’.
So are you saying he has a case of limes desiese. One symptom is spots apearing on the skin.
The “bad spot” is a rather sickly grayish-white. at least one of these lemons has already fallen off the bush. 
It’s now November 24. I’m glad to say that the rest of the lemons on the bush have been ripening normally; we’ll probably pick them for lemon juice (and make lemonade; it’s still quite warm during the day in Southern California) next week.
Glad to hear it,Doug, I was afraid you wer going to have to ake that bush back to the dealer, the’d sold you a lemon.I attempted to send you some links way back then,but when I hit submit I went off line. Don’t know what happened to the post.Some guy in Norway prob got a weird email. this is the only one i can find now.Another ,that is maybe a link from this, had pics similar to what you describe. http://www.biotech.ufl.edu/~pcfcl/canker.htm
Jeeze, hunter how big a slug of tequila do you do with a half lemon? I use about a 8th of a lime with 2 oz or so. your doin like a jelly glass full?
“Pardon me while I have a strange interlude.”-Marx
Mr. John: The lemon bush was already here when we moved in, in June 1987; it has borne quite a few lemons in that time but this is the first time I saw that “canker” or whatever on the lemons. (We live in a mobile home in Gardena, CA; I don’t know how long the bush was there before we moved in.)
My youngest son’s first high school job was in the produce dept. of the neighborhood grocery.
He didn’t know lettuce from cabbage (he got that from me, I didn’t either when I was a kid), he thought limes were unripe lemons.
He thought kiwi was a lemon past its prime, and wondered why people would pay good money for them.
My WAG:
I’ve seen lemons ripen unevenly. Looks like you have one side of the lemon ripening and overripening even before the other side starts to ripen.
Maybe you need to pick them when the first yellow starts to appear so that the entire fruit will ripen simultaneously.
Peace.
Dougie–you can call your local county extension agent for information on horticultural problems like this–it should be listed in your phone book under county offices as XXXX Extension Service or Cooperative Extension, Agricultural Extension or something similar. You may find information on your local land grant university’s home page. The Extension Service was started in 1914 as a link between the land grant colleges and the people–to get research based information out to the citizenry.