I purchased a mandarin tree in a tree-pot while in Bakersfield and subsequently noticed some clear, hard, honey-colored exudate coming from the terminal branches, pretty uniformly over the plant, which is about 2 ft. tall. The leaf color is good (dark) and the branches look healthy aside from the exudate. The exudate is hard, easily separates from the branch, not gummy or adherent. It has fine waviness, and is not shaped like a droplet. It is not sweet to taste. It is located on stems, near petioles, but often on the opposite side from the petiole.
I've seen phytophthera (gummiosis) on plums, tho never on citrus. I know it can infect citrus, but it usually produces a round, drop-shaped exudate that adheres tightly to the stem. However, maybe this is an early stage of phytophthera. But it's odd that it is so uniformly distributed over the plant.
No scale, no aphids. I've had an outbreak of a rapidly moving spider mite, as well, but can't imagine it is related to the exudate.
I've kept the mandarin indoors, unsure whether to plant it outside. or destroy it. Any thoughts? Keith Barton, Oakland, CA.

Could be gummosis. Spray with copper sulfate. Prune off affected parts, then spray again with copper sulfate. Then spray some more copper sulfate after a week and every week for a month. That's how I got rid of it in some of my potted citruses. It was unscientific for me, and worth trying, since I've had excess copper from the fireblight control of my apples.