Q.Lemon Tree – Brown (Rot) Spots
We have had our lemon tree two years. Last year, our small tree (approx. 2′ tall) had an abundance of lemons that ripened in Sept-Oct and were delicious. This year, all was on schedule, but this week we began to notice brown spots that look like rot appearing on several lemons on the tree just as the fruit begins to turn from green to yellow. The skin is in the process of turning yellow, and I would anticipate another two weeks to completely ripen. What causes the brown to appear and what am I doing wrong?

Certified GKH Gardening Expert
There are a couple of disease that can cause this kind of problem. This article has a list and pictures of the different diseases to help you pinpoint which one it is and help for fixing the issue:
http://www.ipm.ucdavis.edu/PMG/C107/m107bpfruitdis.html