Junipers are tough shrubs that can thrive in most growing conditions, including frost and drought. These plants can also tolerate windswept areas, sandy soil, or any type of well-draining soil. Despite this hardiness, however, junipers might still turn brown and appear to be dying, especially during the winter months.
So, do junipers turn brown in winter? In a nutshell, yes – but that does not mean your plants are doomed. Aside from freezing temperatures, the browning foliage can also be caused by several other factors, including pests and fungal diseases. All of these are explained further in this article.
Why are my junipers turning brown?
Junipers are versatile shrubs used extensively for landscape gardening and ground cover. These plants can tolerate harsh outdoor weather conditions, from freezing temperatures to drought. But, despite their toughness, junipers might still face some issues that cause their leaves to turn brown.
Among the most probable reasons your junipers might turn brown are fungal tip blight, root rot, pest infestations, and leaf cankers. All of these issues can detract from the plants’ vigor and beauty. Hence, you need to be well-prepared to prevent any leaf discolorations on your plants by establishing proper care routines, preventative measures, and immediate intervention when necessary.
All that said, leaves turning brown might not always indicate a serious issue. Sometimes, it could just be a plant’s normal reaction to environmental stressors. For example, a juniper turning brown after being transplanted could simply be due to transplant stress. This is normal for most plants, but you can take a few steps during and after the planting process to minimize the impact and help your juniper bounce back quickly.
Extreme weather conditions can also affect the color of your plants’ leaves. For instance, dormancy during the winter months causes juniper leaves to brown. This is one of the plant’s survival tactics to conserve its resources while preparing itself for the freezing temperatures. Again, this is normal, to some degree, and should not cause any serious concerns.
Why do junipers turn brown in winter?
While junipers are generally hardy and cold-tolerant, these shrubs can experience leaf discolorations during sunless periods with sub-zero temperatures. This problem is called winter desiccation.
Winter desiccation, also known as winter burn, is a foliar injury common among trees and shrubs. It happens when too much moisture is lost by the leaves, usually on cold, windy days. Junipers are at particular risk of winter desiccation, which causes their leaves to develop reddish-brown tips. Severe cases might lead to the browning of the entire plant and dropping of the leaves.
While winter desiccation might seem a serious issue, it does not always mean your shrubs are dying. Often, hardy plants like junipers can make a quick recovery once the cold months have passed. So, instead of cutting back your shrubs, be patient and give them time to bounce back. You can also establish a few preventative measures for the next winter season to ensure your junipers do not experience the same damage again.
Junipers turning brown and dying
Juniper needles turn brown for a number of reasons. Aside from winter burn, the plants might also struggle with pests and diseases that can cause irreversible damage to the foliage. Usually, the culprit will be one of these:
1. Twig blight
Twig blight is a disease caused by Phomopsis juniperovora, a fungus that attacks junipers during spring and summer. Some of the tell-tale signs of twig blight infection include leaves that are turning reddish-brown, and dieback of the affected leaves and branches.
For twig blight treatment, fungicides that contain thiophanate methyl or mancozeb are often the most effective. Overhead irrigation must also be avoided, as this watering technique can wet the leaves and promote fungal growth.
2. Kabatina tip blight
Kabatina tip blight is another type of fungal disease that affects shrubs like junipers. It is caused by a fungus called Kabatina juniperi. Juniper plants affected with Kabatina blight often struggle with dieback of the tips of their leaves and branches.
Similar to twig blight, pruning away dead leaves and keeping the foliage dry will be a great help in protecting your junipers from the dreadful disease. Unfortunately, there are currently no fungicides available to cure Kabatina tip blight.
3. Root rot
Root rot is a fungal disease that causes decomposition of the plant’s roots. This problem is most prevalent among overwatered plants. Overly saturated soil inhibits the plant’s ability to absorb oxygen, killing the roots in the process. Soil-borne fungal pathogens called Phytophthora can further exacerbate the issue by attacking the dead roots, leading to the collapse of the entire plant.
Rescuing a juniper with root rot is possible provided that intervention is early. Fungicides often work wonders, but prevention still beats any form of treatment. To avoid waterlogged soil, make sure that the soil is loose and rich in organic matter. Reduce your watering frequency as well, to allow time for the soil to dry out a bit.
4. Bagworm infestation
Bagworms are among the most destructive pests of several ornamental shrubs and trees. Their larvae feast on the leaves of juniper shrubs as soon as they hatch in early summer, around May or June. The larvae are covered with bags while they feed on the plants, hence the name “bagworm”.
Early bagworm infestations can be controlled by manually removing the worms and drowning them in a bucket filled with soap and water. For severe infestations, chemical sprays that contain acephate (Orthene), cyfluthrin, and spinosad are the most effective. The only downside, however, is that these chemicals are highly toxic and can also kill beneficial insects.
5. Spider mite infestation
Spider mites also find juniper leaves an attractive source of nourishment. These tiny, almost microscopic insects feast on the plant’s sap, turning your junipers brown as they drain the juice from the leaves. Without correct treatment, spider mites can quickly reproduce and take over an entire garden.
Forceful spraying of water on the plant’s foliage often works to dislodge these insects from the leaves. Insecticidal soaps and horticultural oils work wonders, too. If you prefer using insecticides to manage severe infestations, make sure to choose products that contain permethrin or pyrethrin.
Juniper care tips for the winter
Winter desiccation might pose some risks to your juniper plants, but with proper care and preventative measures, you can greatly reduce the negative impact and help your junipers recover faster.
One way is to increase your watering during the autumn so that the plant can store more moisture before winter arrives. Mulching is also helpful as it keeps the soil moist and prevents plant dehydration. Use burlap to protect your juniper plants from freezing temperatures and strong winds.
How to prevent juniper shrubs from browning
Browning is undesirable because it detracts from the beauty of your juniper shrubs. Aside from applying the appropriate treatments to correct the underlying issues, you can also employ any of these techniques to keep your shrubs thick and green:
- Plant your junipers in a location with abundant sunlight and good drainage. While these shrubs are tough, they can also be susceptible to root rot and other fungal infections that can induce the browning of their needles.
- Junipers must be planted with sufficient spacing between plants. This will promote air circulation and reduce the risk of fungal growth.
- Keep an eye on your junipers to catch any early signs of infestation – especially of bagworms. If you notice any small, white bags dangling from the plants’ foliage, pick them off and discard them right away.
- Control caterpillar infestations by applying Bacillus thuringiensis on the leaves. Caterpillars are usually abundant during late springtime or early summer. Repeat the application every ten days until the pests are gone.
- Dog pee can stain the leaves of your plants and cause them to turn brown. Make sure to apply safe dog repellents to your garden to keep curious pets from peeing on your shrubs.
- Sanitize your gardening tools before and after using them to avoid spreading fungal pathogens. If you have plants with fungal disease, discard the infected leaves and stems right away. Also rake and discard the leaves on the ground.
- Protect your juniper shrubs from excessive dryness and browning by using an anti-desiccant mist.
Junipers turning brown in winter is a common woe among gardeners. Fortunately, however, these hardy shrubs are rarely killed by winter burn. The real threats to your plants are pests and fungal diseases, both of which can also turn your junipers brown. Without your early intervention, pests and diseases can gradually kill your beautiful shrubs.
The key to reviving your dying junipers is correct diagnosis of the problem, followed by the appropriate solution. So, examine your plants’ symptoms carefully, and hopefully this guide will help you apply the right fixes!
Image: istockphoto.com / Stipe Perkovic