Near the beginning of fall, both of my lemon trees (1.5 yrs old, from the same lemon's seeds) stopped growing new leaves and began putting out the odd growths shown in the picture. They only appear on the top third of the trees, the bottom parts have no growths. The growths seem to develop slowly, though that could be due to the season.

Other than that, the lemon trees seem normal. The other citruses around them (tangerines and key limes) do not have these growths.

These trees have been in pots their whole lives and were not recently moved. The weather has stopped new leaf growth on my citruses, so I have not been fertilizing them or watering as much.

Can anyone identify what these growths are?

Thank you.