Just like last year we are already beginning to see many landscape plants and trees that are showing signs of stress from a variety of factors this year. Excessive heat, drought, insects and disease are among a few and most of your landscape plantings will show stress from these in a variety of different ways.
I have already begun seeing some trees in our area in which the leaves are beginning to change color and some are actually dropping already. With excessive heat and humidity a plant or tree finds it difficult to keep up with water and cooling requirements, even if the soil moisture is at a normal level. The main way a plant cools itself off is by transpiration which is the evaporation of water from the plants foliage. When our relative humidty is high, traspirations is slowed down and the plant finds it more difficult to cool off. This problem inhibits the plants ability to take up adequate moisture from the ground and thus photosynthesis is reduced, leaving the plant stressed.
Stressed plants and trees are far more susceptible to many pests and disease than perfectly healthy plants. Recently we have had very warm and even wetter conditions that will allow for fungal and bacterial spores to beigin attacking stressed plants. Many plants and trees that are under these kind of stressors will initiate what appears to be fall color change and eventually drop foliage at an earlier time than normal. If these plants and trees are fairly healthy up to this point they will likely recover next spring fairly well. The plants that have gotten some of the insect or disease problems may succumb to the stress. Although we seem to face many issues in our landscape with these extreme environmental factors one thing is certain: nature repairs itself well and will continue on.
