Thanks for the pictures. You will certainly need to use every conceivable water saving method, that much is clear. The area of your future house looks very dry indeed. The closest experience I have is gardening in central florida where although there is no shortage of water as a yearly average, there is a quite dry season during the cooler part of the year, the sky is very clear so the sun is bright and hot and the sandy "soil" dries out very dry. There is a also a lot of drying wind that is very hard on food plants and young fruit trees. I suspect there will be several critical factors for you, presuming that the main issue, water, is available. Windbreaks will be super important, and the easiest thing would be to build the house with walls that enclose a sheltered garden. Second, you likely have far too much sun for most annual food crops, so if that sheltered area can have shade from about 1 or 2 in the afternoon might help a lot. With such clear sky and high sun there the morning will probably be enough. In extreme environments the majority of the heat stress on a plant that is not well-adapted will be from the west. Equally important will be crop choices, and that is where it's especially unlikely anyone on this forum will be able to give good info. As mentioned earlier, there must be people in the region who will know everything. We all know of some dry hot climate tree crops: notably date palm and almond, maybe pomegranate, because they are popular foods in the west, but I am pretty sure that there are a number of leguminious trees as well that will grow in those conditions. There must also be some annual type and maybe perennial type greens and other vegetables. I would think it logical that any of the common food crops that originated in the damper and/or cooler climates (which is most, by far) will be a waste of your time and resources.

Plants wilt and die slowly when their roots become compromised. There are several causes of this: 1) Root strangulation. This is best prevented by proper root pruning when planting. If the plant is not too far gone, it might be rescued by digging and removing the soil. Then cutting any circling roots that may be strangling other roots. The roots need to be opened up. On larger plants, some of the top must be removed to compensate for the weak state of the roots. Any time the roots are exposed, they must be kept moistened. Roots that dry out will die. 2) Phytophthora Root Rot or wilt. This root rot is the major killer of rhododendrons and azaleas. It develops when roots are growing in wet conditions. The rot is more prevalent in warm summer conditions. Plants infected with crown rot caused by the oomycete, or water mold, Phytophthora have roots which become clogged with brown oomycete, or water mold, internally. The roots get blocked and the plant wilts and dies. There is not much of any cure for crown rot. Some varieties of rhododendrons are vulnerable (Chionoides, Catawbiense Album, Nova Zembla) and some are resistant (Roseum Elegans, Scintillation, PJM). Sphagnum moss and bark dust combined with good drainage seem to prevent crown rot, but do not cure it. 3) Drought. It may have simply dried out. If you plant rhododendrons or azaleas in late spring, it is very important to give them some extra water while they are growing new roots. Never let the soil completely dry out' it's best to keep the soil evenly moist. Too much water or poorly drained soil might be another explanation of sudden rhododendron or azalea death. Rhododendrons and azaleas have very fine, fibrous roots that are easily damaged by waterlogging, even for short periods of time. 4) Voles. Voles, also known as meadow mice, may have chewed on the bark and roots near the crown of the plant. Sometimes they chew all the way around the trunk and kill the inner bark, resulting in death of the whole plant. Keep mulch away from the trunk to discourage voles. 5) Bark Split. The bark may also split when there are wide fluctuations in temperature in the winter. Rhododendrons and azaleas may begin to come out of dormancy if late winter weather is warm; if a cold snap follows, bark injury is likely, especially in sunny, exposed sites. 6) Wilt and slow death can also be caused by juglone poisoning from walnuts. Plants wilt and die suddenly is usually caused by roots which are girdled by larvae of the Black Vine Weevil, Otiorhynchus sulcatus, Strawberry Root Weevil, Otiorhynchus ovatus, or Twobanded Japanese Weevil, Callirhopalus bifasciatus. Adult weevils feed on the leaves at night except the Twobanded Japanese Weevil which feed during the day. Specimens may be collected during the day or at night for identification depending upon the weevil. The major damage is caused by weevil larvae which girdle the roots and kill the plant. Larvacidal drenches may be used to kill them but are of limited effectiveness. Foliar sprays are very effective at controlling adult weevils when leaf notching starts. Foliar sprays are very effective at controlling adult weevils when leaf notching starts. Foliar sprays must be repeated until no adults emerge. Twobanded Japanese weevils are apparently resistant to carbaryl (Sevin), diazinon, and malathion. Orthene gives good control when applied as a foliar spray and drench. Since weevils can't fly and spend part of each day in the soil and part of each day feeding, you can paint the trunks with Tanglefoot to stop them, but make sure no branches are touching the ground. To answer your question, I think the plant is terminally ill, but would still hold out hope a little longer. You seem to understand the basics very well. Here is a link that might be useful: Rhododendron and Azalea Problems

Im assuming you're from the bp area? Im about an hour south of kato so we've got essentially the same microclimate. In my experience, even the arboretum pecans are pretty iffy in mn. You should remember that they have constant care and supervision. In my opinion they haven't proven themselves here yet.but its always worth a shot. My first choice would be the walnut. I have trees at my house that regularly withstand spring flooding without a problem. The juglone wont be a problem unless you plan on gardening underneath it, but walnuts can also be very messy for a front yard and thays something to remember. We are on the very northern edge of the range of Bitternut hickory. Imho it is a very beautiful tree that makes less of a mess, doesnt produce juglone, and has acceptable water tolerance. Occasionally i have noticed black knot on the bitternuts at the lake cabin, so be prepared for that. Oh that and the nuts would only be edible if you were totally indifferent to your taste buds. I guess what im saying here is, go with a hickory if you can. You'll be the only person in the county with one in your front yard.

Overly wet soil plus high temperatures allow various root rot pathogens to flourish. Unfortunately, your rhododendron exhibits many of the symptoms - leaf spots, drooping foliage even though the soil is wet -'associated with these maladies. Fungicidal treatment once the symptoms are this apparent is pretty much futile. Sand will not improve drainage in this or really any other case. If you want to make a salvage attempt, prune out the dead and wilting branches. Dig up the rhododendron and replant in pure conifer bark on top of the existing soil. The upper 10% of the root ball should be above the soil surface. The drawback of this approach is that whatever pathogens are present will remain and possibly infect other plants. You could also do the pruning, dig up the plant and put in a pot with a mixture of roughly 5 parts bark to 1 part perlite and see if it recovers. If it does, replant next spring. The most prudent course of action would be to dig up the plant and discard it along with much of the soil it grew in. Replace the soil with lots of bark and make sure that any future plantings are above grade.