It could be a rough lemon which is used as a rootstock

I don't understand, how could you be right when this tree came to many  branches from the same base(rootstock), and other branches have normal lemons?

Are some coming from above a graft and others from below?

Many fruit trees are grafted, so the trunk of the tree and the rootstock are not the same variety.

Branches that form and grow from below the graft are from the rootstock and produce fruit of the rootstock's variety, where branches above the graft will produce the intended variety (that of the graft). One tree can even have multiple grafts that all produce different varieties ...

how about location.. big city name.. and a pic of the whole tree ...

any aberrant weather since bloom time .. like a frost or freeze that hit just a random branch.. or some such ...

have you cut it open to see inside of it?? .... ugly rind doesnt mean the fruit inside is necessarily bad ...if you do cut it... take some pix ...

ken

Hi ken_adrian,

I cut one fruit no signs of mold or anything it's clean. 

I find only one branch like this, the second branch is clean. 


On diseases, no major problems except a bit of yellowish leaves here and there on random small branches.. I don't see anything major really

hi sha ... where are you. and are you working on a pic or two of the whole tree .. ill take your word on the fruit ...

ken

Hi, here are some pic