Hi Jon,

It looks like some of the tips of the leaves are yellow (chlorotic). When this happens, the tree essentially loses its "sunscreen" (chlorophyll) and the leaves can burn. 

Fortunately, the tree, as a whole, looks very good and these few leaves will not affect the overall health.

However, a few other things to address:

1. Watering every day is not necessary - adjust your watering to only water 2-3 days per week (and perhaps longer). Not knowing the type of sprinklers you have, 20 minutes may be too much, too little, or just right. I would encourage you to do an irrigation audit and put out several cups in an irrigation zone and collect the water. Then measure it and get an average. Right now, lawns need about 1.0" to 1.5" of water per week (including any rain we get). 

If watering for 20 minutes gives you 1/4" in total water collected in the cups, then you know that you're applying 1.75" of water each week (0.25 x 7 days). This is generally too much. But it all depends on how much water you're collecting.

Overwatering can encourage iron chlorosis - so this may be related to your tree's problems.

Also, try to find out if there are drip irrigation heads to the tree that are also running. 

2. Your tree may have height differences because it's a different species or it may be planted at a different depth. Comparing tree growth to others isn't really fair, because it would be the same as comparing the height of people to other people. Just because they are the same species doesn't mean they would grow at the same rate. Growth rate is affected by many things. Plus, more moderate growth is good because the tree would be less prone to storm damage or breaking.

Let me know what you find out with your irrigation audit!

Thanks for the advice Alison,