Basics of desert survival...

We strongly discourage anyone from making the dangerous journey through the Sonoran desert. There is not sufficient water or resources and temperatures are extreme. It will take days of walking in a harsh landscape and it is not worth risking your life!

Humane Borders warning maps.

Carry foods that are easy to digest, provide calories for fuel to sustain activity and are packed with lots of water - water is always the priority over food. Avoid anything that causes the body to lose water (no caffeine, alcohol or high fiber foods that don't in themselves contain a high percentage of water).

Use prepared food bars/gels designed for endurance athletes if possible because they're made to be easy on the digestive system while providing protein, minerals and fuel.

For non-perishables, dried fruits would be the easiest to carry over several days; fresh fruit would provide more value. Avoid acidic foods if you're going for long periods of time because it will eventually cause irritation - pear, apple, grape are good. But if you could take only one fruit - or just the juice of one - go with watermelon for hot dry climates.

"The rules of threes"
The rules of threes are from an excellent article by Edward J. Otten, MD about desert survival.

Priorities in a survival situation is based on the "rule of threes", you can live 3 minutes without oxygen, 3 hours without warmth, 3 days without water and 3 months without food. Assuming that there are no immediate medical problems or environmental hazards, i.e. fractured pelvis, landslide, flash flood, etc., the top priority in a desert survival situation will probably be water.

If there is a limited amount of water available, then food should not be eaten unless the food contains a large amount of water. The metabolism of food and excretion of waste products requires unnecessary usage of water. Water obtained from lakes, streams, wells or springs should be considered contaminated and purified before drinking. Water may sometimes be found by digging at the outside bend of a dry riverbed or stream. Vomiting and diarrhea caused by contaminated water can be quickly fatal in the desert. Rainwater, dew and water obtained from solar or vegetable stills are relatively pure.

Urine, seawater or brackish water should never be drunk in a survival situation. Liquid from radiators is contaminated by glycols and should never be drunk. Many plants such as barrel cactus and traveler's tree and animals such as the desert tortoise contain water. Such water can be used in an emergency.

...Guide for avoiding dehydration