What Is Tree Sap and When To Schedule a Tree Health Inspection? Insects, Mites & Diseases Tree & Shrub Care Tree sap is a part of a tree in the same way as a branch or root system is. It’s an important component that allows trees to circulate water and nutrients from the roots to the canopy and back. While it’s important to know what tree sap is, it’s also important to understand what it does, why it's normal, and how to monitor it for the health and longevity of your trees. What Is Tree Sap? So, what is tree sap, and why does it matter for your tree’s health? Tree sap is probably best known as the source of sugar used to make maple syrup, but it’s also a necessary component of a tree. All trees produce sap, but the composition of the sap may vary by tree type. But what is tree sap exactly? Tree sap acts as the “blood” of trees; it’s the liquid that circulates throughout the system, providing key nutrients for the tree to grow and prosper. Sap moves through two systems. Phloem is a living tissue that transports sugars (photosynthates) in a two-way system throughout vascular plants. An example of this is leaves that produce sugar through photosynthesis, which then flows through the phloem to be used for fruit, growing shoots, or storage in the roots. Xylem is a dead hollow tube structure that transports water and minerals from the roots to the rest of the plant, and it only moves in one direction. The roots absorb water from the soil, transport it through the trunk via the xylem, and deliver it to the leaves, where it is utilized. Tree Sap vs. Resin: What Is the Difference? While sap transports water, sugars, and nutrients throughout a tree, resin is thicker and is only produced by certain trees for defense purposes. It is typically released at the site of an injury, where it helps protect the tree against insects and disease. Unlike sap, which flows through the tree, resin is produced locally as a response to damage. Is Tree Sap Always Normal? While tree sap is necessary for the health and function of trees, it may sometimes indicate an underlying issue. Look out for symptoms such as: Abnormal amounts of leaking Sap that is dark, smells foul, or looks foamy When it’s accompanied by dieback or other signs of sickness The presence of a sawdust-like material indicates a potential insect infestation Sap is a tree’s way of communicating, and if any of these symptoms arise or you are unsure about your tree's health, it may be time to reach out to your experienced SavATree ISA Certified Arborist®, who can diagnose, treat, and protect your trees with a plan tailored to your environment. Why Is My Tree Dripping Sap? Common Causes While it’s important to understand what tree sap is, it’s also helpful to know what the sap is indicating and when it is time to start thinking about intervening with care. Normal Seasonal Sap Flow Sap flowing from the tree can be completely harmless and normal. As sap is how the tree circulates water and nutrients throughout its system, it’s an important function of the tree. You’ll notice that sap is in abundance at the end of winter and in the early spring. This happens as the temperatures warm up and the tree starts to move the stored sugars upward towards the branches to create leaves, flowers, and fruits. Generally, tree sap is harmless, and the excess flow is temporary as spring hits. What is tree sap communicating when it starts leaking or changing appearance? There are a few things to look out for. Insect Infestations (Borers, Aphids, Scale) Insects can also be another factor affecting sap flow. Specifically, borers, aphids, and scales may contribute to sap flow in trees. Borer insects tunnel into the wood, creating small holes where sap may leak more heavily. Aphids and scales suck sap and produce a sticky substance that mimics sap dripping from the tree. Look for other signs of these insects, such as an abundance of holes in the tree, sawdust, or ants. Fungal Disease and Bacterial Cankers If you notice symptoms in your tree that differ from insect markings, it may be a fungal disease or bacterial cankers. Infections in trees can cause an outpouring of sap or create dark, wet patches on the tree. Alternatively, cankers, dead areas on the bark of a tree, may crack or leak. If you notice these conditions, reach out to your experienced SavATree ISA Certified Arborist®, as they may worsen without intervention. Physical Wounds or Improper Pruning Weather can be unpredictable, and accidents happen. Damage from major storms, lawn or tree equipment, or poor pruning can trigger sap flow. Wounds are generally self-managed by the trees, and the tree will bleed over the wound to compartmentalize the damage. These conditions are usually localized to the site of the tree's injury, but pay attention to the entire system. Environmental Stress (Drought, Frost, Root Compaction) Environmental stress is another factor to consider. Just like in humans, stress can disrupt homeostasis and lead to imbalances. Drought may reduce water flow and availability, leading to imbalances that can cause cracked trees or less effective roots. Watch for a thinning canopy, irregular sap production, or wilting leaves. Frost can damage tree tissue. When temperatures change drastically, water inside a tree's cells expands and freezes, which can lead to suscald, the cracked bark or internal damage. Sap leaks from these damaged areas. You may notice vertical cracks or peeling bark. Compacted soil can happen from vehicles, foot traffic, or time. It can lead to poor root function, which shows up as sparse growth, water pooling in the soil, or surfacing roots. This affects sap because sap relies on water intake, and compacted roots have less oxygen and access to water. Tree Sap Warning Signs That Mean You Need a Health Inspection Sap inside a tree is part of its normal system, moving nutrients and water as needed. Sap outside the tree is a different story. It means something wounded the bark, whether that's storm damage, insect activity, disease, or even human causes like tapping a maple for syrup. Seeing sap on the outside of the tree is a sign that something has happened, and it's worth investigating why. Sap Oozing Alongside Holes or Sawdust in the Bark If you notice a bleeding tree leaking sap from holes in the bark, it could indicate borers or beetles. Sawdust-like material around the holes is a tip-off that borers may be the culprit, and these holes may disrupt nutrient flow. Early detection can lead to better outcomes, and it may be helpful to call an ISA Certified Arborist®. Sap Dripping With Yellowing, Wilting, or Dropping Leaves When changes in sap flow coincide with a visible decline in foliage health, this may be due to internal stress factors. It could point to root damage, improper watering (too much or too little), or poor soil health. If leaves are changing outside of their normal lifecycle, and you see a change in sap production, it may point to a more serious condition. Sap Seeping Near Fungal Growth or Soft Spots on the Trunk When sap appears near mushrooms or soft decaying wood, it could point to internal issues like rot or infection. This can affect the tree's structure and may pose safety risks if left unchecked. It may be time to call a professional to assess tree health and structural risk to determine the level of risk and create the best action plan. Sap Appearing on Multiple Trees in the Same Area When you notice a recurring change in sap among several trees in your yard, you may be dealing with an environmental issue or a sign of something deeper. This can indicate stress issues such as compacted soil, root disturbance, drought, or a pest condition. Excessive Sap Flow Following a Storm or Prolonged Drought Intense weather can create stress on a tree and lead to a higher volume of sap flow. Storm damage can cause external damage like wounds to the tree, while drought can lead to internal damage such as cracking or pressure changes. This makes the tree(s) more vulnerable to pests and other conditions. What Tree Sap Tells an Arborist During a Tree Health Inspection After learning the basics, the question shifts from “what is tree sap?” to understanding what it may be signaling about your tree’s health. SavATree has a team of experienced specialists who help ensure your trees receive the best possible care. Whether the sap has changed viscosity, smell, flow, or color, they can diagnose the problem and create an action plan for the best outcome for your tree. Tree sap carries water, sugar, and nutrients through a tree and is important to the overall health of the system. Understanding what tree sap is and what is normal allows you to better monitor its health throughout its lifetime and provide the tree with optimal care. Contact us today to schedule a consultation with an expert arborist.