If this is a grafted tree then this is a sucker and it should be removed. If this tree is on it;s own roots then it is a water spout and it is ok, but since the tree is fruiting you might be beter if it where trimmed level with the other shoots. If the tree is grafted then the graft should be above the soil level.

Depends. If this is not a grafted tree and growing on it's own roots (may Meyer lemons are grown on their own roots), then it's not a sucker. You don't mention whether your tree is grafted or not, or where you purchased your tree from. I would find out from the grower if their Meyers are grafted, or grown on own roots. That will tell you whether or not to prune this branch away or not.

Patty S.

Looks just like a vigorous growth to me; happens a lot with my garden trees and also my field trees. The difference is my field trees get pruned back according to our defined spacing; while in my garden trees, I tend to let those go for awhile; if it has no thorns, it is not a watersprout; and if the leaves look the same it is unlikely a sucker. If you like uniformity, you could lop it back, which will encourage branching and also more growth in other parts of the tree. In my experience that branch will likely bloom and produce fruits in the Spring; and the fruits will weigh the branch down and create upward growing shoots from the "sides" of the big shoot.