Tag over watering

Why Is My Tree Turning Yellow?

by Texas Tree Surgeons Ask Texas Tree Surgeons, Resources, Tree Health Care

One hallmark of summer is the dense, green foliage on broadleaf trees, but less-than-ideal circumstances can cause the rich green of healthy leaves to become pale, yellowish, and translucent. This loss of color is caused by a deficiency in chlorophyll, which is an essential part of a tree’s nutrient-gathering process. While yellowing leaves can be a sign of several different conditions, in North Texas, yellow leaves on a tree that is usually green are most often a sign of iron deficiency (“iron chlorosis”). Since the historic freeze in February 2021, we have seen a higher number of trees exhibiting iron chlorosis, as they are still recovering from freeze damage and related stress, and their ability to get essential nutrients has been compromised. Luckily, most cases of chlorosis can be remedied by soil amendments and correct, targeted fertilization.

Why Are My Tree’s Leaves Yellow?

While it is expected to see pale green or yellowish new leaves on a tree during spring, the color of these young leaves should darken as they mature. By summer, most healthy deciduous trees should exhibit rich, green leaves. (There are some species of tree with naturally red, purple, or other-colored leaves, but these are less common in North Texas.) If a tree never “greens out,” or turns green but starts to fade well before autumn, there is a systemic health issue at play. Dead or dying leaves can turn yellow, but quickly become dark grey or brown. If a tree’s leaves become pale green or yellow, and stay that way, something is preventing the tree from generating enough chlorophyll.

Chlorophyll is a naturally-occurring chemical in most plants, and performs an important function in leaves. Chlorophyll is responsible for absorbing sunlight and converting it into usable energy for the plant. Chlorophyll is adapted to absorb as much of the correct type of light as possible, and that chemical makeup causes its green appearance. While other chemicals in the leaves can appear as other colors, in most plants, chlorophyll is present in a higher concentration than other pigments, and so it is the one we most clearly see. For a majority of plants and trees, vivid green leaves are a sign of good health and proper nutrition. When leaves begin to decline and die, as in the fall, the chlorophyll fades and other colors can be seen, which is why we see a leaf color change. Similarly, health issues and stress can make plants’ leaves change colors, as the necessary chemicals become imbalanced.

What Can I Do About Chlorosis (Leaf Yellowing)?

While the underlying cause of leaf yellowing (chlorosis) is chlorophyll deficiency, that deficiency may be caused by a number of factors:

  • Mineral/nutrient deficiency
  • Soil acidity/alkalinity
  • Poor drainage/overwatering
  • Root damage/compaction
  • Herbicide exposure
  • Bacterial/fungal infection

Management of the cause of chlorosis is the key to bringing a tree back to health. While some factors, such as soil pH or previous chemical exposure, may not be easily remedied, drainage issues and nutrient deficiencies can often be successfully resolved. Identification of the exact cause of chlorosis can be tricky, and there may be more than one contributing factor. For a comprehensive assessment, contact an ISA Certified Arborist who can examine not only the tree itself, but the surrounding environment, and can ask the right questions to properly understand the tree’s history. Local certified arborists also have access to plant pathologists and other experts, and may be aware of a widespread issue that is affecting your tree.

A NOTE ABOUT WATERING AND FERTILIZATION

A common knee-jerk reaction to a tree or plant not doing well is to immediately increase watering and start applying fertilizer. If the chlorosis is caused by excess soil moisture, however, more watering can cause even quicker tree decline. Similarly, applying a standard, high-nitrogen fertilizer may bring temporary improvement, but can cause further chemical imbalance in a nutrient-deficient tree and stimulate quick growth that is unsustainable. It is important to understand and address the specific cause of leaf yellowing before taking action. Contact an ISA Certified Arborist for assessment and recommendations, and consider sending a sample to a plant diagnosis lab for the most accurate information.

At Texas Tree Surgeons, we love trees and we love our community! We are seeing post-freeze chlorosis on many trees in North Texas, and are working with the International Society of Arboriculture Texas Chapter as well as experts at Texas A&M University and in the tree care profession to provide the best care for freeze-stressed trees. If you have questions about your trees, freeze-related or not, don’t hesitate to get in touch!

Ask Texas Tree Surgeons: What’s Wrong with My Chinese Pistache? [UPDATED]

by Texas Tree Surgeons Ask Texas Tree Surgeons
Another installment in our series of posts where Texas Tree Surgeons answers your tree questions. Are you having problems with your trees and want to know what’s wrong? Let us know!  

Dear Texas Tree Surgeons,

My Chinese pistaches are looking terrible! The leaves are yellowing, the berries are black, and it looks like it’s dying. What’s going on?

Chinese pistache tree with dieback

Extensive dieback on a Chinese pistache

-A.B.

For many years, the Chinese pistache (Pistacia chinensis) has been well-regarded as a landscape shade tree for urban environments in Texas. Although native to China, this species of pistache (related to the nut-bearing pistachio tree) can thrive in a variety of conditions. The Chinese pistache is a fast grower and is resistant to heat, drought, and alkaline soil, all common in North Texas. Like the native red oak, the Chinese pistache is a reliable source of fall color. The dark red berries that female Chinese pistaches produce are not only striking, but can attract birds and other wildlife. For many builders and landscapers, the Chinese pistache is a go-to choice.

Chinese pistache leaves with spotting

If a tree’s leaves are showing spotting or uneven color change, it can be a sign of a problem.

This year, however, we have been seeing unprecedented dieback and wilting of leaves and berries in Chinese pistaches. Entire trees are exhibiting leaf spotting and extensive browning. Similar to the browning present in Italian cypresses the past two years, it seems that the Chinese pistache dieback is caused by a fungus. And much like the Italian cypress issues, there may not be much that can be done at this point.

Water, Water Everywhere

Recent wet weather, combined with poor drainage in clay soils, creates a “wet feet” situation in trees, where their roots are inundated with too much moisture. Trees that are not suited to wet soils are not able to regulate the high moisture level in their roots effectively. The roots then become susceptible to pests, especially fungi, which thrive in damp, poorly-drained soil. As the tree root tissue becomes waterlogged, the fungi are able to gain a foothold in the roots and begin infecting the tree internally. Eventually, the tree’s vascular system itself becomes the mechanism by which the fungal spores are spread throughout the branches, leaves, and fruit. The fungus disrupts cell function in the above-ground parts of the tree, just as it did in the roots.

Chinese pistache berries with infection

Infected berries will rapidly change from red to black

What Can We Do About It?

Unfortunately, there is often little that can be done to improve overall drainage in clay soil. Still, there are some things that tree owners can do to give their trees the best chance:

  • Select native species that are well-adjusted to the North Texas climate
  • When planting, do not plant too deep, and follow good mulching practices
  • For established trees, do not overplant the area near the root collar and inside the drip line with turf grass or other groundcover
  • Consider root collar excavation (Airspading) for trees that were planted too deep
  • Vertical mulching and soil aeration can help break up heavy clay and compacted ground
  • Stop watering and turn off sprinkler systems during periods of heavy rain

Sometimes, despite best practices, fungal infections cannot be avoided. At the first signs of leaf spotting, or unseasonal browning or wilting, contact a certified arborist to diagnose any issues with your trees. Your arborist can suggest a plant health care program. Fungicidal treatments can be helpful, but must be timed appropriately. Once a tree shows extensive browning or dieback, it is often too late for fungicides to be effective.

If It’s Too Late…

If your trees are covered in dead berries and have dropped a lot of leaves already, it is unlikely that a fungicide would have much effect. The best thing to do would be to remove any diseased material from the tree, do as much as you can to improve drainage, and begin a fertilization program. With a good winter freeze, the fungus should die off. In the spring, reevaluate the tree for early signs of new or lingering fungal activity, and treat as appropriate.

At Texas Tree Surgeons, we love trees, and we hate to see a new problem arise that affects a common and much-relied-upon tree like the Chinese pistache. We have submitted samples to the Texas Plant Disease Diagnostic Lab and are awaiting the results. With proper identification, we may be able to better control the particular fungus in the future. We will be sure to let you know what we find out. Keep an eye on our Facebook page for updates!


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We received our results from Texas A&M. The samples we submitted from one Chinese pistache specimen showed evidence of both Phytophthera root rot and Anthracnose stress.

Phytophthera is a pathogen that causes damage to root tissue which can lead to the death of a tree. Phytophthera’s activity is enhanced by wet soil conditions and poor drainage. While fungicidal treatments can be applied, they will be of little benefit unless the underlying moisture and drainage issues are corrected.

Anthracnose is cause by a fungal pathogen, and can take advantage of plants that are already weakened by other stressors. The best method of managing anthracnose is to clean up and dispose of any fallen infected leaves or berries. Fungal sprays may be applied, but are generally not recommended during late summer or autumn, as the trees are preparing to go dormant for the winter, and the fungus should decline naturally.

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As always, please let us know if you have any tree questions. We are always happy to have a certified arborist come out and take a look a small issue to hopefully stop it from becoming a big problem!

Dallas Tree Care – A Complete Guide to Tree Watering [UPDATED]

by Texas Tree Surgeons Resources, Tree Health Care

Summer in Dallas can seem to last forever and just like we need to keep ourselves hydrated, we need to make sure our urban forest has the water it needs. However, tree watering can be challenging to do correctly. We made this guide to help you make sure you’re not watering too little (or too much!).

Watering your trees might sound unnecessary; isn’t that what their deep roots are for? However, roots only work if there is enough moisture in the ground to absorb. In a city setting, however, that often isn’t the case, and our urban trees are left thirsty in the Dallas heat.

With a large portion of the Southwest United States constantly struggling against drought, consistent and correct watering is key. But what does that mean? Is more better? How often and when? See our top tips below for answers to all of your Dallas tree care and watering questions.

Dallas Tree Care – Tip Top Tree Tips

At Texas Tree Surgeons we know that trees have specific needs, but those needs are often overlooked. If you want your trees to really thrive you need to have the right information. We have put together some important points to keep in mind:

  • What time is best for tree watering? This is a great and common question we receive when working with Dallas tree care and watering, and it’s actually easy to remember! Only water with the rule of 8, meaning you can water before 8AM or after 8PM. Simple, right?
  • What method is best for tree watering? This can be tricky, as many tree owners think that their sprinklers are enough, but if sprinklers provide the right amount of water for your small flowers and grass, how could it be enough for your trees too? Trees need a greater water source because they are larger. Use a soaker hose or garden hose for best results.
  • What can I do to help trees retain moisture? Some people have asked what, in addition to watering, they can do to give their trees the upper hand against the Texas heat, and if there’s one thing Texas Tree Surgeons know how to do, it’s beat the heat. If you want the water you put in the ground to stay in the ground, consider mulching, as this helps trees retain moisture and regulates the evaporation. Check out our recent post on mulching!
  • What should I avoid when watering my trees? Texas Tree Surgeons and our Dallas Tree Care Guide recommend never using herbicides on your lawn, or products (like fertilizers) high in nitrogen, as this can open the door to leaf-scald during drought conditions. Ask a certified arborist what soil amendments are right for your trees!
  • What is the best way to water my trees? If you are going to use a garden hose to water your trees, make sure you follow these 3 Dallas tree care steps. 1) Place the hose 1-2 feet from the root flare. 2) Let the hose run at a volume that is flowing but not enough to puddle or stream away. 3) Soak the entire area under the canopy of the tree for best results. And of course, always remember to let the ground around your tree’s base completely dry between waterings.

Dallas Tree Care – Omens of Overwatering

Now that Texas Tree Surgeons has given you the Dallas Tree Care Guidelines for how to water your trees, it’s important to go over how NOT to water your trees. After all, too much water can actually drown your trees! See the 3 quickest signs of overwatering below, so you can be in the know.

  1. Check the top of the root ball to look for saturation – your foot should not sink below grade.
  2. Leaves of an overwatered tree may appear yellow or feel leathery.
  3. Leaves of an overwatered tree may be difficult to pull from the tree.

Just like with people, too much of a good thing is no longer good, so make sure you have the right moisture balance for your trees, just like you do for yourself.

Do You Have a Tree in Need of Dallas Tree Care?

We hope our Dallas Tree Care Guide to Tree Watering helped hydrate your knowledge and refresh your outlook on how to best care for your trees. At Texas Tree Surgeons, we truly believe that trees can become an important part of the community, and so it’s important to take care of them. Look here to see just how much of an impact a giant Pecan can have on a town!

If you think one of your trees might be in need of some assistance don’t hesitate to call, as Texas Tree Surgeons are here to help! We love all trees and would love to check yours out and make sure they are healthy, happy and thriving. Give us a call today at 469-387-6000!

UPDATE 9/2019 – As summer drags on, we often get questions about watering for other landscaping, not just trees, and we wanted to add a link to a comprehensive guide to watering and how to get the most out of your efforts. Thanks to Gary Ashton from Nashville, Tennessee, for the post!

At Texas Tree Surgeons, we love trees and we love our customers, and we want to give you all the tools and information you need to keep your plants healthy during our sweltering summers! As always, if you have any questions about proper tree watering, tree health care, or anything else about your trees, let us know!