Thanks for your question!  The photos appear to include a branch in a plum tree and a limb in an apple tree.  The key is to trace the branches down from the lowest affected leaves, as whatever is causing the symptoms is affecting the whole branch and not just scattered leaves/fruit.  Look for any abnormal symptoms such as cankers (sunken areas), galls (abnormal growths), physical damage, etc.  Prunus species (e.g., plum) can be affected by a soil-borne fungus called Verticillium, but apple typically is not.  This disease can initially begin with death of a single branch or side of a tree.

Regarding watering, soaker hoses can work just fine, although it is often difficult to know how much water they are putting out.  You might think about digging a test hole after irrigating to see how deep the soil is wet.  The amount of water fruit trees need largely depends on whether there is other vegetation growing within their drip line.  If the trees are competing for water, then they will need more water applied than if there is no vegetation competing for water.

You are right that the fruit shouldn't get wet.  In general, when you can water and avoid getting fruit and leaves wet, you can avoid many potential disease problems.  If you wish to use a sprinkler, "low trajectory" impact sprinklers are available that do a good job of throwing a reasonable distance without spraying high up into the canopy.  My experience is that such sprinklers are not readily available at most home and garden centers, so you'll need to seek these at an irrigation specialty store.  Ewing and SiteOne are two such stores in Springfield and Eugene, respectively; I am not personally familiar with irrigation suppliers in Corvallis, but I'm confident one or more exist there somewhere.  You may end up with the sprinkler head sold separately from a base; I recommend a "sled" style base rather than a spike, as the vibration of the sprinkler loosens the spike, especially in wet soil, and then it falls over and doesn't spray properly.

Trace the dead branches downward and let me know what you find.

Thanks for your answer! I just went to the trees and didnt find anything abnormal.The olum tree has a canker at the main trunk, but nothing at the bottom of the dead branches. I didnt see anything in the apple tree.
We think we have a gopher at the orchard. Do you think this could be from gopher damage?
I will go back to the trees and look again, and let you kmow if I find something else later on.

Gophers can make a mess of the soil, and they certainly could damage the roots of a young tree, but these trees appear large enough that they can withstand a little gopher activity.  Also, a single branch dying wouldn't be consistent with gopher damage; if they damaged the roots enough to cause visible symptoms in the tree, those symptoms would occur throughout the tree.

Thanks for taking the time to examine the affected branches downward from the lowest symptoms!  Since there isn't anything obvious at work there, it may not be practical to link the symptoms with a cause.  What is important is to prune the dead materials out of the tree.  It is unclear whether the symptoms may have been caused by a pathogenic organism (e.g., bacteria, fungus), but just in case something like that is present, removing the affected materials and discarding them in the trash is the best way to go.  If you happen to be traveling anywhere near the Benton County Extension Office, the Master Gardeners there could take a look at the branches.

Hi Jeff, we would like to bring the branches today. Where is the extension office? Who should we ask for?
Thansk!

Good morning!  The Benton County Extension Office is located at 4077 SW Research Way in Corvallis.  Ask for the Master Gardeners.  Let them know that we have been corresponding via Ask-An-Expert and share what we have discussed so far.  For the plum tree, it would be most helpful to cut far enough below the dead portion so as to include some live material with the sample.  This allows for examination of the area where the dead portion transitions into the live portion, as that is often where clues can be found.  The apple appears as though it may be impractical to include live wood, as that may involve removing a significant portion of a major scaffold limb; if that is indeed the case, then simply cut back to the scaffold limb, but don't disfigure the tree in order to collect the sample.  Do, however, examine carefully the region where the dead branch meets the scaffold and make note of anything unusual.

Based on our correspondence thus far, you saw nothing obvious externally that resulted in these symptoms.  It is possible the Master Gardeners will find something, but it is also possible there are no obvious visible clues.  In and of itself, that is helpful, because it rules out many of the common possibilities, and it is probably a sufficient diagnosis so long as the symptoms aren't spreading.  If symptoms begin to spread, we can send samples up to OSU for laboratory analysis, but the cost is about $80 apiece for that level of examination, and the apple and plum would be treated as two separate samples. 

I should mention that I am based in Lane County, so while I am not often in the Benton County office, you can reach me at<personal data hidden> if you have additional questions.  Email works too: <personal data hidden>.

Hi Jeff, Master gardeners said is a shot hole borer insect attacking the tree. Apparently happen to stressed or injured trees, so we might have to change our waterimg system.
Thanks!

Thanks for letting me know! Shothole borers are small and easily can go unnoticed (until damage shows up, that is), but once the holes are detected the diagnosis is fairly conclusive. Thank you for taking the samples to the Extension office! Sometimes there is just no substitute for having the sample in-hand to examine. I'm glad you were able to get a definitive answer to your question. It is true that borer damage generally is associated with stressed trees, so anything you can do to ensure the trees aren't stressed will serve to minimize recurrence of this pest.