That's definitely desiccation: the plant can't uptake enough water to counter what it transpires in this heat. It could be due to insufficient moisture at the roots because of too infrequent watering or not long enough each watering or even because the irrigation system is not putting enough water where it's needed ie. the roots. I recommend you probe the soil with a screwdriver to better evaluate moisture and not just eyeball it or go by the clock; it may surprise you.

Thank you sooo much!