Why Does My Tree Have Yellow Leaves?

Common Causes for Yellow Leaves

According to plants, green is “in”. So, when you see that your tree, shrub or plant has some yellow leaves or even dropping leaves (when they shouldn’t be), you might start to panic. Anyone would be concerned if their yard suddenly looks like fall has come early, with yellowing leaves that are dropping like crazy. There are a few reasons why you might be seeing these symptoms in your trees and plants. Take a minute to review our list of the most common causes for yellow leaves.

Water Stress

Drought stress can cause leaves to turn yellow. River birches employ a strategy called compensatory leaf drop during dry spells in summer. This results in the shedding of some leaves to slow water uptake and conserve soil moisture. First, they turn yellow and then they drop. Tulip tree leaves are also susceptible to yellowing and dropping early during dry conditions.

Too much water can result in leaves turning yellow. We see this when tree species that are not tolerant of wet conditions are put in flood prone or poorly drained areas. Arborvitae, White pines, and rhododendrons are good examples of this.

Sometimes we are our trees’ worst enemy. You are attentive and water your newly installed tree regularly. Leaves start to turn yellow, so you water it more, not realizing that you are drowning the tree. It is important that root zones cycle between wet and dry so that roots acquire the right amount of oxygen and water. If you aren’t sure, reach below the mulch layer and take a pinch of soil. If it packs together like clay, it is wet enough. If the soil is dry and breaks apart it is time to water.

Insects and Disease Issues

Plant feeding insects and mites can cause leaves to yellow. They do this by sucking out plant sugars, and or cell contents that either damage or destroy infested leaves. Some common culprits in the landscape include:

• Plant bug
• Lace bug
• Leaf Hoppers
• Leaf miners
• Psyllids
• Spider mites
• Aphids
• Hard and soft scale

Damage will vary depending on several factors but to early detection and intervention is key best outcomes for the affected trees or shrubs.

Rust, scab, and other leaf spot diseases are common in deciduous landscape trees and result in yellowing leaves and premature leaf drop. Evergreen conifers have their own disease issues including needlecast, tip blights, and cankers. Preventative treatments tend to be the best approach to avoid these issues.

Nutrient Deficiencies

Another common cause for yellowing leaves is a lack of micronutrients, the mineral elements essential for the growth of plants. Micronutrients include iron, manganese, zinc, copper, boron, silicon, and molybdenum. This condition, referred to as chlorosis, typically occurs when one or multiple micronutrients are unavailable in the leaves resulting in the breakdown of chlorophyl (the green stuff that absorbs light for photosynthesis). When trees cannot efficiently photosynthesize (convert sunlight into sugar or tree food) they struggle to survive.

Maybe it’s Nothing

Sometimes the yellow on our plants isn’t anything to worry about. “Sunburst” honey locust has yellow leaves throughout the growing season. There are also several cultivars of conifer trees that have yellow foliage. Pines shed old needles each fall that often turn a bright yellow. Dawn Redwood, Baldcypress and Larches are all deciduous fall conifers, and they are prized for their brilliant fall color.

Call us

If you suspect your landscape is suffering from any of these issues, or if you just can’t seem to keep them alive, we can help. When it comes to the health of your trees and the safety of your property, proper evaluation is key. Too often, issues that could be easily resolved with proper maintenance and care result in tree death or property destruction when ignored. Contact Good’s Tree and Lawn Care, one of our Certified Arborists for a tree evaluation.