While summer may be a relaxing time for many of us in Northern New Jersey, it can be the opposite for our trees. A combination of external elements can stress trees in the summer. Knowing what is stressing your tree and what to do about it is crucial to avoiding long-term damage.
In this article, we examine the five most common summer stressors for trees. We explain them and provide some basic methods to help you reduce stress and restore your tree to better health.
Key Takeaways
- Excessive heat is one of the primary stressors on trees in the summer; the problem is especially bad for urban trees, where heat radiation from sidewalks and roads can overheat them.
- Droughts are common in Northern New Jersey and can lead to a tree’s roots dying back and younger trees developing drought cracks.
- Summer is a time of increased disease transmission and insect activity; protect your trees from infection or infestation by keeping them healthy and avoiding any wounds in the summer.
- Increased foot traffic or a summer building project can compact soil, leaving roots unable to expand and take up nutrients.
- Look for signs of tree stress, such as leaf discoloration, early fall colors, premature leaf drop, or branch dieback.
5 Common Summer Stressors to Your Trees
These external factors are the typical stressors of trees during the summer months in Northern New Jersey. Determining what is affecting your tree is often difficult for a layperson (especially when multiple issues may be responsible) and best left to an ISA Certified Arborist.
A pine tree showing the signs of drought stress.
1. Heat is the Primary Stressor for Trees in the Summer
Excessive heat is dangerous for trees, especially in urban areas like Clifton, New Jersey. Urban trees must deal with increased temperatures due to heat radiating off sidewalks and roads. Soil temperatures have reached upwards of 140 degrees Fahrenheit in some cities.
These temperatures can cause extreme heat loading in trees and lead to excessive water transpiration, metabolic problems, and heat lesions.
The best growing conditions for trees are when the temperature of the trees is between 70 and 85 degrees Fahrenheit. In general, trees tend to be around four degrees hotter or colder than the air temperature.
While we don’t have as extreme temperatures as some of our southern neighbors, Northern New Jersey can still reach temperatures that stress a tree. For instance, in Bergen County, temperatures reached nearly 90 degrees in July of 2022. Likewise, Essex County regularly sees temperatures get above 85 degrees Fahrenheit in the month of August.
Placing a layer of mulch around your trees can help them deal with increased heat in the summer, as the mulch regulates soil temperature.
2. Droughts Can Stress a Tree
Summers can see a lack of rainfall in Northern New Jersey. 2024 was no exception, with residents of Essex, Passaic, Morris, and Bergen counties all experiencing drought or abnormally dry conditions.
When the soil lacks sufficient moisture, the fine roots responsible for absorbing it will die back. If the drought persists, the fibrous roots may also start to die. However, if the trees receive water in time, they can begin to regrow their fine roots.
Newly-planted trees may develop drought cracks when exposed to dry conditions. According to research from Rutgers, these typically occur within a year after transplant. Drought cracks are more common in popular Northern New Jersey trees such as:
- Maples
- Honey locusts
- Crabapples
- Mountain ash
- London-planes
For mature trees, supplemental water can help with drought stress. Insert a probe (a screwdriver should suffice) into the soil and see if it is damp. If it’s dry, give your tree supplemental water with a soaker hose (you can use a water bag for newly-planted trees with small drip lines). Newly planted trees often need supplemental water until they are established.
3. Summer is a Time of Transmission for Tree Diseases
Summer is a time of high transmission for most tree diseases in Northern New Jersey. Tree diseases range from non-threatening and cosmetic damage to fatal diseases that can kill a tree within a few seasons. Some of the common diseases we see in Northern New Jersey include:
- Oak wilt
- Dutch elm disease
- Beech leaf disease
- Beech bark disease
- Bacterial leaf scorch
- Thousand cankers disease
To prevent diseases from killing your trees, arborists recommend several strategies, such as:
- Keeping your tree generally healthy and free of drought and heat stress
- Having an arborist apply preventive fungicides and insecticides
- Removing dead or diseased trees
- Sterilizing gardening tools
- Avoiding damaging your tree at periods of peak transmission
PRO TIP: Want to learn more about oak wilt, the deadly disease affecting our state tree? Check out our previous articles on the topic:
The emerald ash borer, a tree pest that attacks ash trees in Northern New Jersey. Photo courtesy of Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org.
4. Insects Attack and Stress Trees in the Summer
Diseases aren’t the only thing we must worry about in the summer, as it is also the time of insect activity. These insects attack your trees, either weakening their structure or spreading a disease that can kill them. Some of the common insects we see in Northern New Jersey include:
- Emerald ash borer (EAB)
- Spotted lanternfly
- Hemlock woolly adelgid
- Oak shothole leafminer
- Scarlet oak sawfly
Prevention methods are generally similar to protecting your tree from diseases. Keep your trees in good health, have an arborist use preventive insecticides, and avoid damaging trees during the summer.
WARNING: EAB can leave an ash tree weak and dangerous to you and your property. Learn more about the importance of removing a dead ash tree with our previous article on the topic: Why You Should Remove Dangerous Ash Trees Now
5. Foot Traffic Can Lead to Compacted Soil
Though more common in the wet winter months, soil compaction can occur in the summer after rain and when foot traffic is high. Summer is also a time when many people do construction on their property, and heavy machinery driving over your lawn will increase compaction.
Soil compaction happens when the soil particles are forced to come together, reducing pore space. Without enough pore space, water and air cannot move through the soil, and a tree’s roots cannot expand to find nutrients. Without remedying soil compaction, a tree or shrub may eventually die.
Preventing soil from becoming compacted is often easier than fixing the problem once it develops. Limiting foot traffic and staying on designated paths will decrease the risk of soil compaction. Hiring a construction company that uses specialized mats that distribute the weight of heavy machinery will also help prevent soil compaction.
If your soil has become compacted, hiring an arborist to use an air spade to break up the soil will reduce compaction. Air spades use compressed air to break up the soil while avoiding harm to the roots.
White birch trees showing the signs of decline due to drought stress. Photo courtesy of Joseph OBrien, USDA Forest Service, Bugwood.org
Typical Signs of Tree Stress in the Summer
It’s difficult for a layperson to determine if a tree is stressed, but with a careful eye, you may be able to detect the signs of tree stress. An ISA Certified Arborist can give you a more accurate assessment of the health of your tree.
Typical signs of stress in a tree include:
- Abnormally small leaves
- Pale green leaf color
- Slow growth
- Early development of fall colors
- Dieback of twigs and branches
- Premature leaf drop
- Wilting leaves
- Peeling bark
- Fungi developing on stems or branches
Aspen Tree Can Help Alleviate Tree Stress
When summer arrives, your trees face numerous environmental stressors. From increased heat, disease transmission, and insect activity to lack of water and soil compaction, summers in Northern New Jersey can be tough for our trees. Tree stress can cause long-term harm to a tree and cause tree failure if left untreated.
At Aspen Tree, we can determine what is causing stress in your tree, alleviate the problem, and then suggest ways to prevent future problems. Don’t trust your trees to just anyone, as you need the expertise from an ISA Certified Arborist to ensure they get the care they need. Call us today at 201-939-8733 or request a quote online.
