Why Are My Trees Dying?

— Written By

Diagnosing tree problems can be a daunting task; they are very complex living organisms. Trees have an expected lifespan and it can be shortened by many environmental factors such as mineral nutrient deficiencies, improper soil pH, poor drainage, soil compaction, long-term weather changes, or suboptimal light exposure. Early symptoms of stress might include reduced growth, abnormal foliage color, vigorous water sprouting, lichen-covered bark or premature leaf drop. A tree under stress becomes more susceptible to insect and disease problems.

Weather affects plants in many ways, some more obvious than others. It may take several years for a tree to show the effects of damage from an event. Trees do not typically die overnight, but decline over several years, entering a slow death spiral. It can be difficult to pinpoint exactly the reason for a tree’s death. Once a tree has entered a death spiral, little can be done to remediate the situation. Oftentimes, the below ground damage to trees is the most significant and the most difficult to diagnose and remedy.

The effects of too much or too little precipitation can be temporary or permanent, depending on the type of plant and how long the condition lasts. Even after a drought has ended, it may take months or even years for a plant to repair damaged root systems and regain the growth capacity it had prior to the drought.

Too much water reduces the amount of oxygen in the soil, resulting in root loss or injury. It can also make the plant more susceptible to many fungal diseases. Waterlogged soils are worse for roots than compacted soils. A high water table is especially common in low-lying areas, or areas where the soil is not well-drained. Standing water is common with high water tables, especially after rain.

Generally, plants grow faster with increasing air temperatures up to a point. Extreme heat will slow growth and also increase moisture loss. The temperatures for optimal growth vary with the type of plant. Extremely hot or cold soil temperatures can also hamper plant growth. When relative humidity levels are too high, or there is a lack of air circulation, a plant cannot make water evaporate or draw nutrients from the soil.

You may have noticed lately that a number of dogwoods are completely defoliated while others may still be holding on to their brown leaves. Unfortunately, most of these trees were showing signs of stress even before the storm. They were either not properly planted, not placed in ideal conditions or were close to the end of their lifespan. Changes in environmental conditions and drought stress have killed trees. Dogwoods are frequently planted in full sun and alkaline soil, but as natural understory trees, they prefer shade, well-drained soil and acidic growing conditions.

If you look at our weather last year we had record cold in January followed by the wettest May on record. In September, hurricane Florence dropped a whopping 22 inches of rain on us. Along with 102 inches of rain in 2018 the additional moisture from the water table had plants/trees sitting in water for days and the root systems rotted from lack of oxygen. Then in 2019, we experienced unseasonably high temperatures in May along with drought.

Florence wreaked havoc on our trees by blowing off their leaves and beating them around for days. After the storm, many trees began to leaf back out which uses up stored energy. This can exhaust a tree that is older or already under a great deal of stress. As normal photosynthesis occurs, trees store carbohydrates for next year’s growth. When normal physiological processes are interrupted trees begin to use up food reserves and are unable to replace them. This drastically weakens the tree and predisposes it to other issues such as insect and disease infestations. Trees unable to continue their basic processes won’t function well and the result is a gradual decline, dieback, and death.

Just remember, no matter how well you plan, Mother Nature is in charge. All you can do is stay aware of weather conditions and try to protect plants as best you can and plant the right plant in the right place. If you do end up losing a few trees, look at it as an opportunity for a whole new garden.