A yellowing emerald cedar is most probably stressed due to an environmental factor that is affecting its general health. The first step in fixing the problem is correctly identifying the cause of the discoloration.
The most common causes of emerald cedars turning yellow are diseases, soil type, pests, drought, root desiccation, leftover twine, overwatering, overfeeding and high temperatures.
In this article, we will discuss the different causes of yellowing emerald cedars and how to remedy each one.
Why is my emerald cedar turning yellow?
Fungal diseases
These usually go hand in hand with other causes of yellowing, because pathogens like to attack plants when they are at their most vulnerable.
If you suspect a fungal problem with your emerald cedar and you can see spots on the foliage in the summer, it is best to remove all the affected branches to stop the spread as soon as possible. If, even after removing the contaminated branches, the problem persists, you might need to use an antifungal spray to bring the infection under control.
Soil type
If you got your plant from a nursery and you plan on planting it outdoors, it is normal for the plant to go through a period of adjustment because the soil it is used to may be drastically different to the soil in your garden. This change in the plant’s living conditions is enough to cause it stress.
It is also not advisable to plant the emerald cedar in soil that is too compact, such as that with a high clay content, and adding organic material on top of the soil will help younger roots develop better.
Emerald cedars like their soil to be a bit moist but not soggy, so you should use well-draining soil that does not retain too much moisture.
Pests
A common pest that attacks emerald cedars is the aphid. These insects suck the sap from the plant and feed on it. The more they feed on the plant, the more damaged the area will become, leading to yellowing of the foliage.
Aphids may be hard to spot with the naked eye, so you really need to examine the plant closely to find these tiny insects, which can be brown, black, green or even orange in color.
You can get rid of aphids by blasting them off with the spray nozzle on your garden hose, or you can use a spray designed specifically for eradicating aphids.
Another insect that attacks emerald cedars is the crawler mite. These are either yellow, brown or red and can be spotted in webbing in the tree’s branches.
You can use an insecticidal soap to get rid of these insects, or blast them off using your garden hose.
A small infestation of either insect does not have a large impact on the emerald cedar, but it can damage the plant aesthetically.
Root desiccation
Root desiccation happens when the roots of the plant dry out and discourage the growth of new roots. This usually happens to the plant during transport, and can lead to the yellowing or browning of the plant. Plants that were grown in burlap are more at risk of root desiccation than those planted in containers, because almost all of their original root system is shed upon excavation.
You can avoid this from happening by watering the plant extensively when it is still growing and adjusting to its new living conditions. Watering is very important,especially in the warmer months in places where the weather is dry. Emerald cedars are more appreciative of deep watering twice a week than of light watering every day.
Leftover twine
When you take an emerald cedar home, before planting it in the ground, check the stem and the roots in case there is any rope or twine left on it that might not break down in the soil. When rope or twine is not removed completely, it might cut into the plant as it grows larger. This may cause yellowing and, if not resolved in time, the plant can even die.
Burlap that has been treated with copper sulphate can also cause stunted growth if it is not removed before planting. Copper sulphate prevents new roots from growing so it is not ideal to keep on the plant after planting.
Overwatering
When you overwater your emerald cedar it can cause the roots of the plant to drown and die. Plant roots need to be able to dry out between watering so that the roots can get access to oxygen. When the roots die, they become susceptible to opportunistic fungi and bacteria, which can cause a condition known as root rot. The rot moves up from the roots to the plant’s stem and foliage, turning them yellow and brown, and could possibly kill the entire plant.
You can avoid overwatering your emerald cedar by making sure you plant it in well-draining soil that does not retain too much water. Adjust your watering schedule depending on the season and the weather. Water the plant more frequently during the summer or whenever the weather is hot, and water less frequently during the winter.
Overfeeding
If you fertilize your emerald cedar too much or too often, it can lead to damaged roots and yellowing leaves.
Fertilize the plant three times during its growing period and refrain from fertilizing during the summer, as this is when the plant goes into dormancy.
If you have little to no experience of handling fertilizer, do some research first, or hire a professional to do the job for you.
High temperature
The foliage of the emerald cedar can turn yellow or brown if exposed to the extreme heat of the summer sun or warm winds. This does not really do much damage to the plant’s overall health, but it can affect the aesthetic of the plant. If the yellow or brown foliage is bothering you, just prune off the damaged parts.
Conclusion
A yellowing emerald cedar is suffering stress caused by an environmental factor. You can fix this problem by identifying what exactly is causing the stress in the first place. The faster you identify the cause, the sooner your plant will be able to recover.
The most common causes of yellowing emerald cedar are diseases, soil type, pests, drought, root desiccation, leftover twine, overwatering, overfeeding and high temperatures.
Image: istockphoto.com / Elmar Langle