People often ask if trees are affected by the hot and dry weather. The short answer is yes. Trees are essentially pumps. A large healthy tree can move a significant amount of water from the ground and out of its leaves on a daily basis. A tree uses water to move nutrients and elements around to get things where they are needed within the plant. In summer there is less water available and so the trees have strategies to help economize water loss.
There are a couple of coping mechanisms trees use in defense against hot temps. The first is closing their stomata. Trees exchange gas through these holes in their leaves and release water vapor through them . By shutting down their stomata ,trees limit water loss. A second way trees defend against water loss is through shedding leaves. Dropping leaves is a more aggressive way to limit water loss. We often get calls in summer where people think their tree may be dying due to this leaf drop. In fact it is a tree’s coping skill. Since leaves are how and where trees make their food, leaf drop can be somewhat stressful on your plants. Helping your trees through watering is an option . This watering should be done with a soaker hose and the hose should be left on for a couple hours. For large root zones you may have to move the soaker hose a few times for full coverage.