Why are the leaves on our walnut tree turning yellow then brown?

Question

This tree is about 2 years old and is in our orchard in the inland empire of southern CA. We water by drip once a week for about 3 hours but have stepped up the water a month ago to twice a week.All the other trees are fine and some are new and some are mature.

Thank you.

Answer 1

Some counties have an extension service.  Call them.  You may have to take a leaf sample in but they can probably give you advice over the phone.