Olive Tree

This could be caused by more than one issue but the most likely cause (or aggravating factor) could be too much water. We recommend you inspect the soil around the roots closest to the tree and at the feeder roots (at the dripline). If this tree is getting “indirect water” as you decribe it, on a regular basis then the soil is probably too wet for this tree. Mediterranean plants (like Olive trees) don’t do well with regular water and become much more susceptible to root rot and crown rot diseases. If this damage is occurring on just one side of the trees, that could be a clue especially if the irrigation is watering that same side regularly; could this be the cause of the “random” damage you see. We’ve included a link from the UC Davis website that has info about how to look for/test for some of the common disease of these treess
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/olive.html