Be Aware of Heat Stress for Trees this Summer
(July 05, 2019)
Be aware of heat stress this summer
You aren’t the only one that dreads the dog days of summer; your trees and plants suffer from the heat too. Did you know that high temperatures alone can cause significant damage to you plants’ health? High temperatures reduce photosynthetic rates faster than they reduce respirations rates. The result: carbohydrates produced by photosynthesis are used faster than they can be replaced – an imbalanced budget! Higher temperatures increase the loss of water through stomates in the leaves, thereby increasing the demands on the root system to take up water in order to cool themselves via transpiration. (Usually high temperatures are also accompanied by low rainfall – insult to injury). Cellular membranes also become unstable and result in ion leakage within the leaf cellular structure.
So how do plants cope with high temperatures? One way is through the formation of heat shock proteins (HSPs). HSPs are found in humans and other animals as well and perform the same function as in plants: maintain the integrity and function of proteins in high heat. HSPs are formed in response to rising temperatures and help to stabilize proteins to ensure cell functioning. HSPs help to moderate metabolic reactions that would otherwise speed up and cause an imbalance of metabolites and acidification in cellular tissue. Calcium also plays a critical role in temperature stress adaptation by modulating enzyme activity and stabilizing membranes. There are physical adaptations as well, such as increasing leaf hairs and waxes, changing leaf morphology to reduce light interception, and changing leaf orientation.
If your tree is showing signs of already experiencing heat stress, water deeply using drip irrigation. A soaker hose or garden hose on low flow work best. Make sure to water at the dripline, instead of right at the trunk, since root density is highest toward the edge of the canopy and the entire root system should receive the water it needs. Taking care of tree health before they experience the stress of summer heat can make a big difference, as well. Preparing plants for heat stress consists of the horticultural basics: plant properly in high quality soil, manage soil fertility, and properly irrigate. Taking the proper steps will go a long way with helping your trees survive the dog days of summer, and when fall arrives they can breathe a sigh of relief.