Pine Tree Disease- HELP

I live in Tucson AZ- I have over 30 Eldarica Pines- they are also know as Afgan or Mondell Pines- over the past few years I have noticed tip dieback and have sprayed with copper based fungicides a few times and also have used Bayer advanced tree and shrub numerous times on all trees- well this year it has gotten worse- I thought I had the upper hand but have noticed whole branch die back on lower branches of some trees...and dieback among smaller shoots along the center trunk giving the pines a "Thinning" or "Sparse" appearance- on a few of the trees I have what I think are cankers, a dried crack in the bark with lots of dried yellow crusty sap running down the trunk, these cankers are higher up on the main trunk....I have had an arborist come and look but he didn't tell me anything I didn't already know...he sprayed a few trees, charged me $200 and there was no improvement- there are no obvious bore holes with dried pitch around them-can't see any obvious signs of infestation- I have looked on branches and pine cones for little black specks indicating fungus spores but there are none....I have sprayed with copper based fungicides and recently used Cleary's 3336 as a spray....I have used Bayer advanced multiple times and it seems to help with new growth but it doesn't last....I think I'm losing ground and need help- what else can I do....these are drought tolerant pines but I do water regularly, especially now with this problem- most of my pines are at least 10 feet tall....some are 25 feet tall- on one large pine all of the needles are brown from tip half way down to base, there is new growth, but before long those needles turn brown half way down as well....what is going on and what else can I do??? I refuse to let them die, I have been working a lot of years on my forest in the desert...Please help

I'm more versed in Spruce needlecast, but that does sound like your issue. Applications must be consistent and timed properly to get control of needlecast.. Often requiring a 2-3 year treatment cycle before new damage isn't noted.
There are some good extension articles out there to help you determine if you have it or not.. I usually look at the stomata of the needles in spruce.
There are different forms of needlecast, but none of them are fun to manage. Judicious pruning with sterile technique are involved in most of my successful treatments. If you are treating, be sure to do things to help the trees recover from that additional stress. Also, in my experience, needlecast has a tendency to show up where there are already cultural or environmental issues happening to reduce tree health and resistance, like poor soil quality. How you water can have a serious impact on spreading diseases like this as well.. Or overwatering, in the case of plants that don't normally get a lot of rain.
A soil test thru your local extension can give you some surprising insights into hidden issues in your landscape, when all else doesn't seem to make sense. That would also be a great place to touch base with someone who has insight into local issues, that isn't trying to sell you a product.
Hope some of this helps.