Well, what kind of mandarin is it? Some mandarin cultivars, such a Seedless Kishu produce very small fruits. Also, if your tree sets an inordinate amount of fruit, it will cause all the fruits to be small, so thinning will help increase the size of the remaining fruits. Tell us what cultivar mandarin, and we can tell you if small is more the norm.

Patty S.

It's a Kawano Mandarin tree. It's weird, because last year they produced larger fruit.

Cara

Well, based on what I've been able to read about Kawano Wase satsuma madarins, they are smaller than other satsumas to start with, and they are prolific. So, wondering if perhaps you had a very heavy crop last year, and the tree, still being young, is tending to alternate bear a bit, with less and smaller fruit this year. I am not familiar with this cultivar, as I think it is mostly an NZ or Australian cultivar, but this is what I would suspect, based on what I've been able to find out about it online. You could also check with your local citrus growers in your area, and see what they have to say about this cultivar.

Patty S.