Q. I have a new ‘Early Grande’ peach which produced over eighty blossoms. I removed fifty of them and harvested the rest. The leaves are turning yellow and dropping off. I am watering the tree for 40 minutes, three times a week, on alternate days right now, so the tree is getting 16 gallons a week.
A. If you're peach tree is getting yellow leaves and these are dropping and the canopy is sparse (thinning, not very many leaves) I am guessing it needs more water applied. If the soil is bare, watering every other day sounds about right for most soils. If the soil is covered with a surface mulch then you might be able to squeeze two days between irrigations.
Use the same technique to make sure the water is wetting the soil 18 to 24 inches deep. Just like fig, peaches will improve with a surface mulch. Peach trees at the University Orchard in North Las Vegas that are 7 feet tall and 7 feet wide are receiving 90 gallons of water each week in a basin that collects the water around the trunk that is 6 feet in diameter during the hot summer.
The term "too much water" has a double meaning. Too much water can mean that too much water is applied at a single time. Too much water can also mean that the water is applied too often. It is much more damaging to plants when water is applied too often than it is if too much water is applied in a single application. Enough water should be applied to wet the depth needed. That is a given. That will never change. What will change during the seasons is when to water, i.e. how often. Plants will use 500 to 800% more water in July and August than they do in January.