Answer: Flame seedless grapevines are one of the best for growing in Mesa. They do best with full morning sun and shade from the hot afternoon sunshine. If you don't have your grapevines in a protected area, what you are seeing is sun scald. Building a trellis or other sunblock will improve the appearance of the leaves but as your grapevines grow, only the outer leaves will be affected - those on the inner parts of the vine will be protected from hot afternoon sunshine. I can't gauge how much water your grapevines are getting. They need a deep soaking once or twice a week (about as much water as your lawn). You can try probing the soil to see how deeply the water is traveling. Use a stick or a metal probe. If you can push it into the soil about 12", the roots are getting adequate water. If you cannot push the probe that deeply into the soil, the roots may be suffering drought even though you water 3 times a week. It just means the water is not penetrating the soil deeply enough. I hope this helps you troubleshoot!
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